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90tbirdsc
06-13-2013, 02:36 AM
Ok, On my mission to figure out why my car isint running well I remembered last year when all I had was a IC fan, single 2.5 exhaust, cat delete, and CAI and 10% sc pulley. I bought the car with those mods and one day on the quest for more power for free I unbolted the rear section of the exhaust, thinking that less restriction has to equal more power. Well I was wrong, the car was very loud and much slower everywhere in the rpm range than when It had full exhaust and mufflers.

SO my question now is that with my ported late model, mp inlet, 75mm tb, 3.5 intake, lmaf, 42# injectors,255lph walbro, FMIC, dual 2.5 exhaust off the manifolds to single 3 behind tranny and dump, could that exhaust be a issue? Should I run it to the back of the car and put mufflers on it?

Miguel5671
06-13-2013, 04:10 AM
Ok, On my mission to figure out why my car isint running well I remembered last year when all I had was a IC fan, single 2.5 exhaust, cat delete, and CAI and 10% sc pulley. I bought the car with those mods and one day on the quest for more power for free I unbolted the rear section of the exhaust, thinking that less restriction has to equal more power. Well I was wrong, the car was very loud and much slower everywhere in the rpm range than when It had full exhaust and mufflers.

SO my question now is that with my ported late model, mp inlet, 75mm tb, 3.5 intake, lmaf, 42# injectors,255lph walbro, FMIC, dual 2.5 exhaust off the manifolds to single 3 behind tranny and dump, could that exhaust be a issue? Should I run it to the back of the car and put mufflers on it?

No a 2.5-3-2.5 set up will handle just about anything u throw at it

Stock catz are a restriction
Stock resonator is biggest restriction
Stock mufflers not so much but yes

Port ur stock manifolds that will also help

The motor needs a bit of backpressure from the exhaust
But not as much as it had stock
However something like dual 3" exhaust would be complete Overkill

Now aftermarket resonators X pipes H pipes true duals and different mufflers will be mainly sound difference

How ever I felt a better response on mine after adding dual borlas and its so much more quiet matter of preferences
Also to help with drone if u use mufflers keep tips the way stock were aiming down sort off helps alot with drone...

90sc35thann
06-13-2013, 05:22 AM
It's never a good idea to have any exhaust back pressure. Think about it. Back pressure leads to exhaust being pushed back into the cylinder through the exhaust port under operation. When is that ever a good idea?

My setup is kooks mid length to two 2.5 inch into a magnaflow resonator with twin 2.5 inlet out to a single 3 inch then back to a Y fitting that splits to two 2.5 inch into two magnaflow mufflers.

As a special note you can see straight throu my mufflers and resonator so there is no restriction in my exhaust at all and I have to to say my exhaust is quiet and has no drone. So you can have a free flowing exhaust that isn't obnoxiously loud. You would never know my car has headers with the exhaust as opened up as it is.

Very stealthy............until wot. LOL

Miguel5671
06-13-2013, 05:34 AM
It's never a good idea to have any bexhaust back pressure. Think about it. Back pressure leads to exhaust being pushed back into the cylinder through the exhaust port under operation. When is that ever a good idea?

It does tho the engine does need some backpressure , not the 17psi of back pressure the stock system offers lol but run open headers on dyno will be loud
Then Run dual 3" no back pressure
Run an exhaust thats about what the car needs and there will be differences open headers or oversized free flowing piping will hurt performance
I saw a 15 muffler comparison sound and power levels on ls1 forum let me search it , where no mufflers had a loss in hp compared to having having mufflers

I Had shorty headers and ram the car a couple miles to muffler shop it was very unresposive and loud

AFter that I got 2.5 downpipes no catz to a magnaflow resonator single 3" out all the way back to differential oumpkin it made a big difference in response and quickness .... couole months after I got a Y pipe that split that 3" to dual 2.5s with dual borlas and the car feels More responsive now
From my experience the little back pressure helped
compared to 17psi

Miguel5671
06-13-2013, 05:40 AM
It's never a good idea to have any exhaust back pressure. Think about it. Back pressure leads to exhaust being pushed back into the cylinder through the exhaust port under operation. When is that ever a good idea?

My setup is kooks mid length to two 2.5 inch into a magnaflow resonator with twin 2.5 inlet out to a single 3 inch then back to a Y fitting that splits to two 2.5 inch into two magnaflow mufflers.

As a special note you can see straight throu my mufflers and resonator so there is no restriction in my exhaust at all and I have to to say my exhaust is quiet and has no drone. So you can have a free flowing exhaust that isn't obnoxiously loud. You would never know my car has headers with the exhaust as opened up as it is.

Very stealthy............until wot. LOL

^ mine is like that lol but on idle it sounds choppy like cammed and it isnt lol


What I mean is as long as he ditched the stock horrible exhaust components he will be ok with a 2.5-3-2.5 or dual 2.5 or 2.25 dual or whats the other set up some use dual 2.5 to a single 3.5 to 2.5 again any of those set ups will be good for anything most SCs will see unless its a crazy 10s SC :D

Miguel5671
06-13-2013, 05:47 AM
Heres what I was sort of talking about :D

Gray chart is off tccoa others of the Ls1 forums

90sc35thann
06-13-2013, 06:41 AM
Let me say this. When you drove to the shop with open headers the reason it hurt performance is because your ECM had no idea how much fuel to add. Your O2 sensors were too close to fresh air. For example when I was running logs with open headers my KAMFR's were all over the place because they kept getting signals from the O2's that were all over the place.

The two charts you provided were comparing decibals and mufflers. None of which has anything to do with power. As for the dyno charts. Different mufflers can certainly affect performance based on restriction.

Still I have never had an engine where a little back pressure was better than none.

The ls1 article doesn't tell me much either as the delta in HP numbers is negligible. Ditto to the tccoa link.

If anything a good exhaust system will help to suck out the exhaust, which is why valve overlap on a cam helps improve performance. The exhaust system actually helps pull the intake charge into the cylinder. A system with back pressure would defeat this purpose.

Read the second paragraph of the article at the section called "overlap: how much is too much?"

http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/viewall.html

Miguel5671
06-13-2013, 07:08 AM
Let me say this. When you drove to the shop with open headers the reason it hurt performance is because your ECM had no idea how much fuel to add. Your O2 sensors were too close to fresh air. For example when I was running logs with open headers my KAMFR's were all over the place because they kept getting signals from the O2's that were all over the place.

The two charts you provided were comparing decibals and mufflers. None of which has anything to do with power. As for the dyno charts. Different mufflers can certainly affect performance based on restriction.

Still I have never had an engine where a little back pressure was better than none.

The ls1 article doesn't tell me much either as the delta in HP numbers is negligible. Ditto to the tccoa link.

If anything a good exhaust system will help to suck out the exhaust, which is why valve overlap on a cam helps improve performance. The exhaust system actually helps pull the intake charge into the cylinder. A system with back pressure would defeat this purpose.

Ok I understand completely about the o2s reading ambient air,
The LS1 charts dynoed the same car swapping mufflers
Even tho the differences were minor having no mufflers hurt performance and torque lets say if all those mufflers were no restriction (just example) why did running no mufflers made less power ? I have the borla pro xs and they are not a straight through design I do believe they make .5psi back pressure each, now my next question is why then would a free flowing 3" dual exhaust hurt performance it is no restriction isnt it?

ANd yes I know the exhaust scavanges the gases out that is why a big pipe will make the car loose torque
Also then a true free flowing exhaust would be a mandrel bend straight through headers
Ok so say back pressure isnt needed but velocity if gas is at low rpms u need the velocity for gasses to come out quicker but at high rpm a small pipe diameter creates back pressure doesnt it ? Because the engine is trying to oush the gas through a smaller volume path so in a true free flowing free back pressure exhaust would be an overkill pipe with no back pressure headers mufflers resonators yet it would kill ur low end torque
That is why an exhaust set up must be chosen right for each application? As little back pressure from components as possible yet a diameter pipe that can be at the optimal point to maintain power and velocity

Or im I way off and should just go to sleep :D?

Miguel5671
06-13-2013, 07:21 AM
I read it and I DO understand that back pressure isnt needed
But, there will be back pressure in an exhaust system to make it optimum for both low and high rpm
So the lowest back pressure possible while having a pipe diameter that helps velocity is optimum :)


http://www.sccoa.com/articles/cwexhaust.php

TAke a read on this even having 2.5 piping and free flowing mufflers and catz and resonator u will still have back pressure then very little and that's the good part the least amount there the better but u will have it if u have the right piping for the motors power range
ONLY if u go to an oversized diameter pipe then u almost completely eliminate backpressure but that would kill ur low end torque like using dual 3" or 3.5"
That is why the pipe must be sized correctly to have good gas velocity at low rpms even if it means it will have a little bit of back pressure at high rpms

I Think only this wouldnt apply to turbo vehicles because the exhaust is driven by the turbo
Both pulling and pushing the gas

E_train
06-13-2013, 07:37 AM
I was talking to a co-worker the other day about back pressure in exhaust.

We were discussing this article which explains it well, IMO.

http://www.veryuseful.com/mustang/tech/engine/exhaustScavenging.pdf

I'd love to put a variable exhaust valve like Turbo Subaru STIs have.

90sc35thann
06-13-2013, 07:46 AM
There are many reasons no mufflers hurt the engine performance but none of which had anything to do with the loss of back pressure in the exhaust system. IMO


It probably had to do more with the afr and spark going out of whack due to the change in exhaust.

Miguel5671
06-13-2013, 08:35 AM
There are many reasons no mufflers hurt the engine performance but none of which had anything to do with the loss of back pressure in the exhaust system. IMO


It probably had to do more with the afr and spark going out of whack due to the change in exhaust.


Probably that, no I know u would want the least back pressure possible but im saying there will be some backpressure unless u go with an overkill pipe that will hurt low end torque but little as possible pressure while retaining the low end is the best wouldnt that be ?

90sc35thann
06-13-2013, 08:41 AM
Serious drag racers run open headers. I don't think it is hurting their torque. :)

Miguel5671
06-13-2013, 08:49 AM
Serious drag racers run open headers. I don't think it is hurting their torque. :)

Because they have high hp :D and take off on high rpm they dont see low end at all they stall and take off at mid to high rpms ?

The bigger pipe less back pressure helps on high rpms because there is little to no back pressure but that car doesnt see low rpms its going WOT since start

Exhaust Velocity is just to aid the daily drivers :D

I think im gonna do more researching and see if I find anything else related but for now I gotta sleep a bit :/

Talk to you later man ! Nice talking to you

XR7 Dave
06-13-2013, 09:11 AM
Serious drag racers run open headers. I don't think it is hurting their torque. :)

Don't be so sure.

A properly sized exhaust system is beneficial. But to actually have a properly sized exhaust system means you'll have to throw out some of your favorite ideas first which is something most people refuse to do.

Maintaining velocity is important in any case. Maximum scavenging is not always the rule. It's too complex to really get into here, but the article above is a very good start.

sics6
06-13-2013, 09:23 AM
I have to agree with Miguel on this one. Velocity improves torque, which helps really in most rpm's where people generally drive...low and mid range. Unless your never ending racing your car you're not driving in the high rpm range much. There's a difference in throwing out hp numbers and useable hp. A well balanced exhaust is essential.

Mike8675309
06-13-2013, 09:39 AM
A well balanced exhaust is essential.

to clarify, a well balanced exhaust is essential for optimum performance.

But a well balanced exhaust is not particularly necessary for good or even great performance, only optimum performance.

Because the SC cars tend to have positive displacement blowers, they can get away with a much less efficient exhaust system and still see good performance. Now you can't have plugged converters and expect reasonable performance, but put a reasonable exhaust system on with reasonable mufflers and you will find that you can spend the rest of your money on something other than exhaust.

Switching to open exhaust would require re-tuning on a carb motor just like it requires re-tuning on an electronically controlled motor.

r429460
06-13-2013, 10:42 AM
The best exhaust system has negative pressure.
Thats virturally impossible.
Headers, collectors, x-pipe, all to speed the exhause gas flow.
To attempt to creat negative pressure (vaccume), to help with
removing the burned fuel from the piston bore and combustion chamber.

archerman0531
06-13-2013, 11:20 AM
It's never a good idea to have any exhaust back pressure. Think about it. Back pressure leads to exhaust being pushed back into the cylinder through the exhaust port under operation. When is that ever a good idea?

My setup is kooks mid length to two 2.5 inch into a magnaflow resonator with twin 2.5 inlet out to a single 3 inch then back to a Y fitting that splits to two 2.5 inch into two magnaflow mufflers.

As a special note you can see straight throu my mufflers and resonator so there is no restriction in my exhaust at all and I have to to say my exhaust is quiet and has no drone. So you can have a free flowing exhaust that isn't obnoxiously loud. You would never know my car has headers with the exhaust as opened up as it is.

Very stealthy............until wot. LOL

All the new ford motors HAVE to have some back pressure in the system or you end up burning the exhaust valves.
I know this is 20 something years earlier, but, there might need to be a little back pressure to not internally damage the engine.

90sc35thann
06-13-2013, 11:49 AM
It certainly is an interesting debate. As velocity increases pressure decreases. This is Bernoulis Law and also the principle on how a venturi tube operates. You can't have increases in velocity and increases in pressure. It doesn't operate that way. The faster you get the exhaust moving the faster the pressure drops. So you could say that the reverse would also hold true. As pressure increeases velocity decreases. Meaning if you have back pressure you are decreasing velocity.

You are going to have a hard time getting me to agree that back pressure in an exhaust system is a good thing.

Of course you need efficiency for the catalytic converters to operate properly, for the cylinders to get hot enough, for the EGR system to work properly, for the system to be quiet enough for the general public, etc. etc.

Of course you want velocity to increase especially at the point of the collector so that it creates a decrease in pressure which aides in removal of the exhaust gases. If the system has restriction then you are slowing down velocity which increases pressure.

The collector of a header behaves very similarly to the narrowest point of a venturi tube. IMO


BTW - I have been wrong before and I'll be wrong a number of times before I leave this earth but I am sticking to my guns on this one...............for now. LOL

KMT
06-13-2013, 12:54 PM
You are going to have a hard time getting me to agree that back pressure in an exhaust system is a good thing.


Outright, pure scavenging wastes energy in some examples, so don't be too quick to dismiss value.

One of the functions of headers and the collector is to harvest the pop from one cylinder when that exhaust cycle hits the atmosphere out of the tail pipe, where an echo ring travels backwards to help push wasted intake charges (during valve overlap) back into other cylinders. That is a good example of valuable back pressure.

Miguel5671
06-13-2013, 01:08 PM
It certainly is an interesting debate. As velocity increases pressure decreases. This is Bernoulis Law and also the principle on how a venturi tube operates. You can't have increases in velocity and increases in pressure. It doesn't operate that way. The faster you get the exhaust moving the faster the pressure drops. So you could say that the reverse would also hold true. As pressure increeases velocity decreases. Meaning if you have back pressure you are decreasing velocity.

You are going to have a hard time getting me to agree that back pressure in an exhaust system is a good thing.

Of course you need efficiency for the catalytic converters to operate properly, for the cylinders to get hot enough, for the EGR system to work properly, for the system to be quiet enough for the general public, etc. etc.

Of course you want velocity to increase especially at the point of the collector so that it creates a decrease in pressure which aides in removal of the exhaust gases. If the system has restriction then you are slowing down velocity which increases pressure.

The collector of a header behaves very similarly to the narrowest point of a venturi tube. IMO


BTW - I have been wrong before and I'll be wrong a number of times before I leave this earth but I am sticking to my guns on this one...............for now. LOL


Your statement is true, but the exhaust behaves different it actually behaves both ways I believe yes at High Rpm the lower the velocity the higher the pressure physics cannot be changed which hurts performance and that is why a Non back pressure system would benefit a High Rpm situation

However... at low RPMs the engine isnt producing the power lets throw made up numbers here at idle say 700rpm the engine wouldnt be pushing the gas at the same rate it would from 5000rpm
So at idle the engine would need the scavenging effect which would come from the smaller or better said correct sized piping to aid velocity at low mid rpms its not until the engines revs are high enough to where the engine is now Forcing the gas out which is what u mean by backpressure being bad and yes at that point back pressure would mean the engine to use power to push gas out instead of transfering that power to the wheels
So choose between almost No backpressure which is like open longtubes or full exhaust high rpm benefits or low end torque response

To make it shorter you are right partially as well as I am and yes back pressure is bad but back pressure will exist in an optimum exhaust system in order to keep the best of both worlds low end torque and high rpm power :)

Miguel5671
06-13-2013, 01:26 PM
to clarify, a well balanced exhaust is essential for optimum performance.

But a well balanced exhaust is not particularly necessary for good or even great performance, only optimum performance.

Because the SC cars tend to have positive displacement blowers, they can get away with a much less efficient exhaust system and still see good performance. Now you can't have plugged converters and expect reasonable performance, but put a reasonable exhaust system on with reasonable mufflers and you will find that you can spend the rest of your money on something other than exhaust.

Switching to open exhaust would require re-tuning on a carb motor just like it requires re-tuning on an electronically controlled motor.

Yes seems like a mild SC would respond great to just ported manifolds no catz x pipe where the stock resonator was and choose ur favorite mufflers in place of stock ones stock Piping it will do just great that would be a cheap exhaust system mostly DIY kinda deal if u can weld

The bad thing about the stock system is the high psi 15-17 back pressure was over the positive displacement of the blower which most stock SCs do 12psi of boost
12psi vs 15psi just by seeing this its ovious the engine looses more power by fighting a greater back pressure I really wonder why ford restricted the SC so much when they could have beat European competition alot more as well as the corvette the first tbird back then was supoosed to be a race car then changed to luxury
Ford could have made best of both worlds with the SC

I Think ford knew this but they also knew that making a more suited exhaust for the SCs would smoke their pony cars and they didnt want that... lol guess they were afraid of sales

90sc35thann
06-13-2013, 01:34 PM
Your statement is true, but the exhaust behaves different it actually behaves both ways I believe yes at High Rpm the lower the velocity the higher the pressure physics cannot be changed which hurts performance and that is why a Non back pressure system would benefit a High Rpm situation

However... at low RPMs the engine isnt producing the power lets throw made up numbers here at idle say 700rpm the engine wouldnt be pushing the gas at the same rate it would from 5000rpm
So at idle the engine would need the scavenging effect which would come from the smaller or better said correct sized piping to aid velocity at low mid rpms its not until the engines revs are high enough to where the engine is now Forcing the gas out which is what u mean by backpressure being bad and yes at that point back pressure would mean the engine to use power to push gas out instead of transfering that power to the wheels
So choose between almost No backpressure which is like open longtubes or full exhaust high rpm benefits or low end torque response

To make it shorter you are right partially as well as I am and yes back pressure is bad but back pressure will exist in an optimum exhaust system in order to keep the best of both worlds low end torque and high rpm power :)


That's because Ford had their sights set on the BMW 5 series as well as Mercedes Benz. From the articles I read back in the day that was the target market. Yeah i am that old. LOL

Miguel5671
06-13-2013, 01:37 PM
That's because Ford had their sights set on the BMW 5 series as well as Mercedes Benz. From the articles I read back in the day that was the target market. Yeah i am that old. LOL

I bet they were trying to compere with all the IRS and the electronic suspension and all those luxury deals we have for our years

BUT they could have made a true example of how they could muscle up and outpower everyone by still having the most luxurious car with all the options avaliable u could think of :)

I believe the engineers owned mustangs -.- and were jealous lol

MadMikeyL
06-13-2013, 03:09 PM
The bad thing about the stock system is the high psi 15-17 back pressure was over the positive displacement of the blower which most stock SCs do 12psi of boost


Where are you getting this 15-17psi of back pressure in the exhaust number? I've never measured it on a stock SC, but that number has to be wrong. Ever drive a car with clogged cats? That sputtering and backfiring and complete loss of power is caused by about 4psi, so with 17psi the car would be a complete dog!

And since I'm responding to this thread, I'll throw my input in. Backpressure in the exhaust system is absolutely horrible under all circumstances in all internal combustion engines, whether gasoline or diesel, supercharged, turbocharged, or naturally aspirated. If your system is creating even half a psi of backpressure at any point in the rpm range, your car would make more horsepower at that same rpm with a freer flowing exhaust system. I can't even tell you how many times I have gone through this in multiple posts in multiple forums, but this backpressure myth still runs rampant on the internet, and it is a pet peeve of mine. Any backpressure is always a bad thing. People frequently confuse backpressure with velocity, but as 90sc35thann pointed out, the laws of physics tell us that it is the exact opposite. In a perfect setup, the perfect exhaust system would be under negative pressure, or vacuum at the rpm where the motor makes peak power. The vacuum will not only help suck the exhaust gases out, but also helps suck the intake charge into the cylinder during the cam overlap, which creates a greater pressure differential between the intake manifold and the cylinder, which fills it with more air and fuel. In case you were wondering, another device that creates a greater pressure differential between the intake manifold and the cylinder is...wait for it...a SUPERCHARGER! So a properly sized exhaust system will have a slight supercharging effect on the motor. The vacuum in the exhaust that creates this scavenging supercharging effect is created by the velocity of the exhaust gas heading towards the tail-pipe. The greater velocity, the less pressure or the more vacuum the engine sees at the exhaust valve, and the more power it makes. At lower rpms there is less exhaust gas to expel, so you don't have much velocity. At higher rpms with a smaller pipe, the exhaust can't flow fast enough and it backs up creating backpressure and eliminating scavenging. With a smaller exhaust system, scavenging occurs at lower rpms, but then immediately after that rpm it starts to become a restriction which creates back-pressure, which as I have said already is bad for power, so you would sacrifice a lot of power on the top end for a very small increase in power on the bottom end. It simply is not worth it. As you go larger with the exhaust system, you need more exhaust gas to fill the pipe so you reduce velocity at low rpms, which raises the point at which this peak vacuum occurs, and if you have sized the system correctly, your scavenging will peak at the same rpm as you make peak horsepower. So in effect the only way of saying a system is too large is if it doesn't see peak velocity until after the max rpm the engine will ever see. In that case, you would lose out on this scavenging effect, but considering how minimal the effect is, and how drastic the effect of a system that is too small, you are always better off erring on the side of too large, from a performance standpoint. In the real world, there are other concerns such as packaging, sound, drone, price, etc. and if you go with a smaller pipe because you want it to be quieter and the slight loss in power is worth it to you, then go for it, but if you are looking at it from a performance standpoint, better to go a little too big than a little too small. Oh, and just to reiterate, BACKPRESSURE IS ALWAYS BAD!

Miguel5671
06-13-2013, 03:28 PM
Where are you getting this 15-17psi of back pressure in the exhaust number? I've never measured it on a stock SC, but that number has to be wrong. Ever drive a car with clogged cats? That sputtering and backfiring and complete loss of power is caused by about 4psi, so with 17psi the car would be a complete dog!

And since I'm responding to this thread, I'll throw my input in. Backpressure in the exhaust system is absolutely horrible under all circumstances in all internal combustion engines, whether gasoline or diesel, supercharged, turbocharged, or naturally aspirated. If your system is creating even half a psi of backpressure at any point in the rpm range, your car would make more horsepower at that same rpm with a freer flowing exhaust system. I can't even tell you how many times I have gone through this in multiple posts in multiple forums, but this backpressure myth still runs rampant on the internet, and it is a pet peeve of mine. Any backpressure is always a bad thing. People frequently confuse backpressure with velocity, but as 90sc35thann pointed out, the laws of physics tell us that it is the exact opposite. In a perfect setup, the perfect exhaust system would be under negative pressure, or vacuum at the rpm where the motor makes peak power. The vacuum will not only help suck the exhaust gases out, but also helps suck the intake charge into the cylinder during the cam overlap, which creates a greater pressure differential between the intake manifold and the cylinder, which fills it with more air and fuel. In case you were wondering, another device that creates a greater pressure differential between the intake manifold and the cylinder is...wait for it...a SUPERCHARGER! So a properly sized exhaust system will have a slight supercharging effect on the motor. The vacuum in the exhaust that creates this scavenging supercharging effect is created by the velocity of the exhaust gas heading towards the tail-pipe. The greater velocity, the less pressure or the more vacuum the engine sees at the exhaust valve, and the more power it makes. At lower rpms there is less exhaust gas to expel, so you don't have much velocity. At higher rpms with a smaller pipe, the exhaust can't flow fast enough and it backs up creating backpressure and eliminating scavenging. With a smaller exhaust system, scavenging occurs at lower rpms, but then immediately after that rpm it starts to become a restriction which creates back-pressure, which as I have said already is bad for power, so you would sacrifice a lot of power on the top end for a very small increase in power on the bottom end. It simply is not worth it. As you go larger with the exhaust system, you need more exhaust gas to fill the pipe so you reduce velocity at low rpms, which raises the point at which this peak vacuum occurs, and if you have sized the system correctly, your scavenging will peak at the same rpm as you make peak horsepower. So in effect the only way of saying a system is too large is if it doesn't see peak velocity until after the max rpm the engine will ever see. In that case, you would lose out on this scavenging effect, but considering how minimal the effect is, and how drastic the effect of a system that is too small, you are always better off erring on the side of too large, from a performance standpoint. In the real world, there are other concerns such as packaging, sound, drone, price, etc. and if you go with a smaller pipe because you want it to be quieter and the slight loss in power is worth it to you, then go for it, but if you are looking at it from a performance standpoint, better to go a little too big than a little too small. Oh, and just to reiterate, BACKPRESSURE IS ALWAYS BAD!

Where im getting the back pressure reading is this article I posted above ... 15-17 because the condition of ctz clogged or not could make a difference too I believe
Now let me read the message got get out the rain first lol
http://www.sccoa.com/articles/cwexhaust.php and ive had a few people also tell me the back pressure tests they made on. Stock exhaust were similar

Miguel5671
06-13-2013, 03:46 PM
Where are you getting this 15-17psi of back pressure in the exhaust number? I've never measured it on a stock SC, but that number has to be wrong. Ever drive a car with clogged cats? That sputtering and backfiring and complete loss of power is caused by about 4psi, so with 17psi the car would be a complete dog!

And since I'm responding to this thread, I'll throw my input in. Backpressure in the exhaust system is absolutely horrible under all circumstances in all internal combustion engines, whether gasoline or diesel, supercharged, turbocharged, or naturally aspirated. If your system is creating even half a psi of backpressure at any point in the rpm range, your car would make more horsepower at that same rpm with a freer flowing exhaust system. I can't even tell you how many times I have gone through this in multiple posts in multiple forums, but this backpressure myth still runs rampant on the internet, and it is a pet peeve of mine. Any backpressure is always a bad thing. People frequently confuse backpressure with velocity, but as 90sc35thann pointed out, the laws of physics tell us that it is the exact opposite. In a perfect setup, the perfect exhaust system would be under negative pressure, or vacuum at the rpm where the motor makes peak power. The vacuum will not only help suck the exhaust gases out, but also helps suck the intake charge into the cylinder during the cam overlap, which creates a greater pressure differential between the intake manifold and the cylinder, which fills it with more air and fuel. In case you were wondering, another device that creates a greater pressure differential between the intake manifold and the cylinder is...wait for it...a SUPERCHARGER! So a properly sized exhaust system will have a slight supercharging effect on the motor. The vacuum in the exhaust that creates this scavenging supercharging effect is created by the velocity of the exhaust gas heading towards the tail-pipe. The greater velocity, the less pressure or the more vacuum the engine sees at the exhaust valve, and the more power it makes. At lower rpms there is less exhaust gas to expel, so you don't have much velocity. At higher rpms with a smaller pipe, the exhaust can't flow fast enough and it backs up creating backpressure and eliminating scavenging. With a smaller exhaust system, scavenging occurs at lower rpms, but then immediately after that rpm it starts to become a restriction which creates back-pressure, which as I have said already is bad for power, so you would sacrifice a lot of power on the top end for a very small increase in power on the bottom end. It simply is not worth it. As you go larger with the exhaust system, you need more exhaust gas to fill the pipe so you reduce velocity at low rpms, which raises the point at which this peak vacuum occurs, and if you have sized the system correctly, your scavenging will peak at the same rpm as you make peak horsepower. So in effect the only way of saying a system is too large is if it doesn't see peak velocity until after the max rpm the engine will ever see. In that case, you would lose out on this scavenging effect, but considering how minimal the effect is, and how drastic the effect of a system that is too small, you are always better off erring on the side of too large, from a performance standpoint. In the real world, there are other concerns such as packaging, sound, drone, price, etc. and if you go with a smaller pipe because you want it to be quieter and the slight loss in power is worth it to you, then go for it, but if you are looking at it from a performance standpoint, better to go a little too big than a little too small. Oh, and just to reiterate, BACKPRESSURE IS ALWAYS BAD!

Again Im not saying its good but there will be some back pressure in the exhaust system
Yes smaller pipe bigger velocity of gas flow on low rpms higher back pressure at High rpms because the engine is producing more gas that doesnt fit on the smaller volume pipe so it is wasting power to push it out


Bigger pipe more volume so at high rpms there is less back pressure but u lose ur low end torque because raising pipe diameter decreases velocity!
At 700 rpm the engine pushes gas at say 50cfm these are made up example numbers
So on a 2.5 pipe that would have xx velocity
Now say u get 3.5 pipe ok at 700 rpm the engine STILL is pushing gas at 50cfm nothing changed however
The 3.5 pipe has way more volume and the velocity will be lower than the 2.5

7000rpm a 2.5" pipe will be genersting say 3psi of backpressure
At 7000rpm 3.5 will make .5psi back pressure

So yes I know at high rpm the bigger pipe benefits the high rpm in getting the exhaust gas out quicker since gas is going at say 250cfm now the bigger pipe will get it out quicker and not cause a fraction of pressure compsred to the smaller pipe

So the whole point here is
The engine will have some back pressure to work better on low rpm
Yet a properly sized exhaust that still mskes the decent power on the high rpm while generating as little backpressure possible

Now if back pressure is so bad show me an exhaust set up that is 0psi back pressure ?
Mufflers x pipes x pipes catz manifolds headers collectors Bendz on the pipes will all account for a bit of back pressure
Which means that no matter how much u wamt a true no backpressure exhaust u will have some if u have a correct sized exhaust
Again going too big will hurt performance and if it had been a myth then why when someone goes 3.5 exhaust or 3 duals on their 150hp lose power and response ? Because everything has to work together I believe

Its not a myth
And physics also state by law that a bigger diameter pipe will have in fact more volume we know that
Which will mean less restriction backpressure at high rpm

So of that has less backpressure why then will that hurt performance ? ? ? ...

U want to have the right size pipe that maintains low end torque will keeping as little backpressure as possible that is my belief yet u will have backpressure one way or the other ...

sics6
06-13-2013, 03:53 PM
Just a little side note. The supercoupe was first being developed to beat the grand national, but after gm decided to kill the grand national because of chevy whining about the corvette then ford set its sights on the european market. The supercoupe was actually supposed to be twin turbo, solid axle car. So ford then changed to handling, and supercharging the car to chase bmw, but also choked it to death because they didn't want to embarrass their poster boy the mustang.

90sc35thann
06-13-2013, 04:20 PM
Interesting. I had read an article that the MN12 was to be an IRS from the beginning and the lead engineer got fired/left shortler after release because he insisted the car stay IRS much to the shagrin of the Ford exec's and when the car came in over weight and over budget he left. I think the car came in $386 dollars over budget per unit as I recall and about 400 pounds too heavy.

Miguel5671
06-13-2013, 04:24 PM
Interesting stuff to hear
Maybe if ford made the tbird its luxury track car at those years it could still be in production today maybe ?

Kurt K
06-13-2013, 04:30 PM
Just a little side note. The supercoupe was first being developed to beat the grand national, but after gm decided to kill the grand national because of chevy whining about the corvette then ford set its sights on the european market. The supercoupe was actually supposed to be twin turbo, solid axle car. So ford then changed to handling, and supercharging the car to chase bmw, but also choked it to death because they didn't want to embarrass their poster boy the mustang.

Just curious where you heard that the Super Coupe was originally being designed to compete with the Grand National.

Mike8675309
06-13-2013, 05:02 PM
Yes seems like a mild SC would respond great to just

Stock exhaust makes a number of compromises. new down tubes, better cats, free-er flowing and reworked resonator clean up nearly all of the bad ones.

The numbers found in that article really can't be used to get specific, but they work well at showing the relative improvement that can be found with cleaning up the stock exhaust.

overall the exhaust tuning is much more than backpressure and how little or much you have. Specifically on our motors, but even on motors in general. Attempting to boiling it down to a simple statement simply is not possible.

one point to keep in mind. pressure doesn't push. vacuums pull and gases move from high to low pressure.

As XR7 Dave stated

It's too complex to really get into here, but the article above is a very good start.

bowez
06-13-2013, 05:13 PM
Here's my $.02.

Exhaust has X amount of energy in it. That energy is used to A fill the exhaust tube and B move through the tube. As RPM increases the energy X increases.

Ideally all gases expand uniformly but as a fluid they expand to fill their container (the tube).

So at low RPM there is not a lot of energy available to fill a large diameter tube and not move through the tube. This is why too large off a pipe hurts torque.

This all assume distance stays the same.

Hot and tired if doesn't make sense.

Miguel5671
06-13-2013, 05:26 PM
Here's my $.02.

Exhaust has X amount of energy in it. That energy is used to A fill the exhaust tube and B move through the tube. As RPM increases the energy X increases.

Ideally all gases expand uniformly but as a fluid they expand to fill their container (the tube).

So at low RPM there is not a lot of energy available to fill a large diameter tube and not move through the tube. This is why too large off a pipe hurts torque.

This all assume distance stays the same.

Hot and tired if doesn't make sense.

+1 !!!


Thats what im trying to get across
The right piping

As for the backpressure this will go on and on :D

90tbirdsc
06-13-2013, 06:23 PM
Here's my $.02.

Exhaust has X amount of energy in it. That energy is used to A fill the exhaust tube and B move through the tube. As RPM increases the energy X increases.

Ideally all gases expand uniformly but as a fluid they expand to fill their container (the tube).

So at low RPM there is not a lot of energy available to fill a large diameter tube and not move through the tube. This is why too large off a pipe hurts torque.

This all assume distance stays the same.

Hot and tired if doesn't make sense.

+1 !!!


Thats what im trying to get across
The right piping

As for the backpressure this will go on and on :D

yeah, a lot of reading. Posted this last night and hop back on to see If anyone has said anything yet and I have 3 pages of replies lol

So I think im going to put exhaust on it anyways and see what it does. I think with the stock heads and cam having pretty much no restriction could hurt my 1000-3500 rpm performance. Maybe, we will see. Gunna run the singe 3 out behind the diff and then make a y pipe and then 2 90 degree bends into flowmasters and then out.

LIVipers
06-13-2013, 06:34 PM
Are you sure those rotors are timed correctly and that your outlet isn't over ported on your blower? I know you were having issues earlier on

Miguel5671
06-13-2013, 06:36 PM
yeah, a lot of reading. Posted this last night and hop back on to see If anyone has said anything yet and I have 3 pages of replies lol

So I think im going to put exhaust on it anyways and see what it does. I think with the stock heads and cam having pretty much no restriction could hurt my 1000-3500 rpm performance. Maybe, we will see. Gunna run the singe 3 out behind the diff and then make a y pipe and then 2 90 degree bends into flowmasters and then out.

That will work man :)

Heres a pull on no mufflers
Just catlezz 2.5 downpipes to a magna res
ANd 3" pipe out back to where the irs is at

https://www.youtube.com/watch?v=lVmaQ7Ltoxs&feature=youtube_gdata_player

And here same set up plus Y pipe dual 2.5 borlas

https://www.youtube.com/watch?v=bEw9BfAQNGM&feature=youtube_gdata_player

Just the first run rest of video is mostly a cruise

Theres alot on this topic but to ur original question u dont need to upgrade ur exhaust mufflers are a preference I couodnt stand the noise on mine without them

peagnit2
06-13-2013, 06:58 PM
I have long suspected that the reason that little wives tale about back pressure was originally propagated was to sell cheap mufflers for a nice profit.

I think we where fooled.

Miguel5671
06-13-2013, 08:49 PM
It certainly is an interesting debate. As velocity increases pressure decreases. This is Bernoulis Law and also the principle on how a venturi tube operates. You can't have increases in velocity and increases in pressure. It doesn't operate that way. The faster you get the exhaust moving the faster the pressure drops. So you could say that the reverse would also hold true. As pressure increeases velocity decreases. Meaning if you have back pressure you are decreasing velocity.





People frequently confuse backpressure with velocity, but as 90sc35thann pointed out, the laws of physics tell us that it is the exact opposite.


The greater velocity, the less pressure


Ok Here I made some simulations of velocity to prove my point that smaller diameter pipe has more velocity than bigger pipe

As velocity increases back pressure does NOT decrease

The bigger the pipe the less back pressure the less velocity at which the gas flows (pros high rpm cons low rpm)

The smaller the pipe the higher velocity the higher bsckpressure (pros low rpm cons high rpm)

Moral off the story an in between set up that benefits both low and high rpm range is best (and yes there will be some back pressure) not 10 or 15psi but maybe 1-3psi which is a huge difference ad by all means more than 3 times less restrictive than the stock set up


As u can see on pics the comparison was 2, 2.5, 3, 3.5, and 4" pipe

THE velocity Decreased as the diameter of pipe increased...
But the smaller the pipe in an exhaust the more back pressure it creates...

90sc35thann
06-13-2013, 09:57 PM
Your charts show feet per second given identical pressures and volumes. Given Identical volumes of fluid, with identical pressure behind it, the fluid in the smaller diameter conduit will always travel a greater distance as the fluid in the smaller conduit requires longer conduit to move identical volumes of fluid. Meaning the smaller diameter conduit requires a greater distance to contain an identical volume of fluid. (A taller column of conduit is required to hold identical volumes of fluidi in a smaller diameter)

What you want to do is measure volume in relation to pressure given identical sized conduit.

Please keep in mind I have always been discussing back pressure as being a power robber. I never mentioned conduit diameter. You can have two exhaust systems both using 2.5 inch tubes but one less restrictive than the other given mandrel bend, vs, kink bend, baffled muffler vs, flow through, etc. you get the picture.

Ask yourself this. Given identical sized exhaust tube with identical engines one system has zero restriction and the other 5 psi of restriction down stream. Which one flows more gas?

Take a garden hose as an example. You turn the hose bib so the valve is all the way open. You have 50 feet of garden hose. Now pinch the hose at the end causing restriction and back pressure. Does it now flow more water? Of course not. The water coming out speeds up and sprays further but the key you are missing is ithat volume is greatly diminished. There was a pressure drop on the upstream side of the pinch in the hose causing velocity to increase beyond the pinch in the hose but it still flows less water.

So yes I will take a less restrictive system everyday of the week that flows higher volumes of gas.

90sc35thann
06-13-2013, 10:36 PM
Don't be so sure.

A properly sized exhaust system is beneficial. But to actually have a properly sized exhaust system means you'll have to throw out some of your favorite ideas first which is something most people refuse to do.

Maintaining velocity is important in any case. Maximum scavenging is not always the rule. It's too complex to really get into here, but the article above is a very good start.

Dave what ideas would I need to toss? I am game. I'll take a look at anything and I think you know that. :-)

Miguel5671
06-13-2013, 11:00 PM
The charts show so many things ft/s cm/ minute
Cm/hr its just a representation no actual numbers

It does prove however that as velocity increases pressure Doesn't decrease
Because a 2" exhaust pipe will have more back pressure than a 3" velocity decreases and back pressure decreases as well

Now lets leave that aside for a bit
Lets simplify here

How would you make a 0psi backpressure exhaust system ?

Back pressure is not something to be glad of in the exhaust i agree but how could one achieve zero back pressure while maintaining sufficient velocity for the gas at low rpms ? ...

Since the flow rate of the gas in exhaust is the Variable
The flow will increase at high rpm and over come smaller pipes which is when there will be back pressure
At low rpms the velocity on the small pipe would be higher giving u more of the scavenging effect and you wouldn't lose the low end torque

And the other set up would be vice versa



So how does one make a 0 backpressure exhaust system while maintaining velocity to maintain low end torque ?

Back pressure is bad but it will always be there
I dont think theres such thing as to a 0 or negative back pressure exhaust .I think ur set up even mandrel bend and free flowing mufflers ud still have .5-3 psi

And as mike said it was impossible because 4 psi would generate back fire etc how have we been using our SCs at 10+ psi back pressure :/

90sc35thann
06-13-2013, 11:17 PM
You are right there is always some sort of back pressure as any conduit, even straight will have some resistance or back pressure. I just argue that the least amount possible is best. The longer the conduit the greater the restriction. Similar to voltage loss over distance.


You are however incorrect. You need to study Bernoulli's principle. As velocity increases pressure always decreases. You missed my point. You need to measure velocity in relationship to pressure within the same size pipe. You can't compare two different pipes. Now you are comparing apples and oranges.

Just ask yourself this given the same size diameter pipe. If you want your gases to travel more quickly or with more velocity you need less pressure or less restriction. Remember pressure is just a measurement of restriction. The greater the restriction the less velocity. The less restriction the greater the velocity. So velocity always increases as pressure decreases. There is no getting around that.

So ask yourself this. How do you get more velocity? You need less restriction or less pressure. No way around it.

Miguel5671
06-14-2013, 12:06 AM
You are right there is always some sort of back pressure as any conduit, even straight will have some resistance or back pressure. I just argue that the least amount possible is best. The longer the conduit the greater the restriction. Similar to voltage loss over distance.


You are however incorrect. You need to study Bernoulli's principle. As velocity increases pressure always decreases. You missed my point. You need to measure velocity in relationship to pressure within the same size pipe. You can't compare two different pipes. Now you are comparing apples and oranges.

Just ask yourself this given the same size diameter pipe. If you want your gases to travel more quickly or with more velocity you need less pressure or less restriction. Remember pressure is just a measurement of restriction. The greater the restriction the less velocity. The less restriction the greater the velocity. So velocity always increases as pressure decreases. There is no getting around that.

So ask yourself this. How do you get more velocity? You need less restriction or less pressure. No way around it.

Yes I understand that , I was assuming the exhaust we were talking off had to be gutted from the restrictive components :D its why a stock SC would be good with gutting cats dumping the resonator because they restrict flow throught l that puny stock piping even worse and make over 8psi of back pressure or so if we follow that sccoa article

And yes a 2" pipe with cat, resonator, and muffler would be alot more restrictive than a straight 2" pipe

More restriction more back pressure if pipe diameter isnt a variable to change then yes the statement is correct.

TinManSC92
06-14-2013, 12:51 AM
What a great read!!! I enjoyed that

90tbirdsc
06-14-2013, 12:58 AM
Are you sure those rotors are timed correctly and that your outlet isn't over ported on your blower? I know you were having issues earlier on

Outlet isn't as big as some ive seen so I don't think that is the issue, Supercharger rotors/inlet still arnt out of the question though.

going to put the exhaust back to how it was last year just bigger just to eliminate a variable, then build a 3.5 intake just to keep narrowing stuff down.

bowez
06-14-2013, 06:54 AM
Need to think of this like a water pump and head pressure. The system can only pump the fluid so far and every fitting/bend/obstruction reduces that distance.

LIVipers
06-14-2013, 08:05 AM
Outlet isn't as big as some ive seen so I don't think that is the issue, Supercharger rotors/inlet still arnt out of the question though.

going to put the exhaust back to how it was last year just bigger just to eliminate a variable, then build a 3.5 intake just to keep narrowing stuff down.

Why not swap back on the blower that you had originally? You know that one worked, and all these issues started once you put the ported blower on

XR7 Dave
06-14-2013, 08:56 AM
Dave what ideas would I need to toss? I am game. I'll take a look at anything and I think you know that. :-)

Everyone has closely held ideas that aren't necessarily based in science. Being willing to let go of your favorite thing is often where you start making progress.

I'll just give you all a few tidbits based on hundreds, maybe thousands of hours of dyno time.....


As has been pointed out, exhaust systems are of minimal impact on a supercharged engine.
Exhaust back pressure can be very high in a supercharged application, 15psi is actually pretty normal, 25psi is not unheard of. The HP difference between 5 and 25psi is less than you think. The db difference is massive.
Headers are more or less a waste of money on a supercharged engine. There is a good reason supercharged drag cars don't use them. The biggest benefit of tuned headers is the scavenging effect which is often detrimental to a supercharged engine. Yes, I said detrimental.
Backpressure is never good. But velocity and backpressure are components of each other. Velocity=good, pressure=bad. But you can't separate the two so you have to balance them for maximum advantage (or minimum impact if you prefer). This is easier said than done.
Most exhaust "knowledge" is based on natural aspiration. I've never found any qualified research or even enlightened opinions on exhaust systems for supercharged engines. It can be both perplexing and enlightening if you ponder that for awhile.
Generally speaking less is more. Knowing when and how to apply that axiom is the key.


I know that is cryptic, but it is what it is...... :)

Mike8675309
06-14-2013, 10:32 AM
I was assuming the exhaust we were talking off had to be gutted from the restrictive components :D its why a stock SC would be good with gutting cats dumping the resonator because they restrict flow throught l that puny stock piping

The main problem with the stock exhaust is not the diameter of the piping. It is the limits to exhaust flow (velocity) caused by:
Severe bends at converter(s).
Small diameter exhaust manifold outlet
small diameter resonator to exhaust pipe coupling.

Open up the outlet of the exhaust manifolds to smooth the transition into new smoother flowing down tubes with bullet style converters (gutting the stocker still leaves the 90 degree turn), rework the connection to the resonator to remove tubing diameter changes or delete it. That's all I'd worry about until I was pushing over 300hp at the rear wheels.

David Neibert
06-14-2013, 01:09 PM
As has been pointed out, exhaust systems are of minimal impact on a supercharged engine.

True...all the times I upgraded the exhaust on my 91 SC, there was pretty much no improvement in performance. Just got louder. Not saying the stock exhaust is acceptable, just saying don't expect to gain the kind of power you can actually feel when switching over to headers or a big dogg exhaust system.

David

Miguel5671
06-14-2013, 01:58 PM
Everyone has closely held ideas that aren't necessarily based in science. Being willing to let go of your favorite thing is often where you start making progress.

I'll just give you all a few tidbits based on hundreds, maybe thousands of hours of dyno time.....


As has been pointed out, exhaust systems are of minimal impact on a supercharged engine.
Exhaust back pressure can be very high in a supercharged application, 15psi is actually pretty normal, 25psi is not unheard of. The HP difference between 5 and 25psi is less than you think. The db difference is massive.
Headers are more or less a waste of money on a supercharged engine. There is a good reason supercharged drag cars don't use them. The biggest benefit of tuned headers is the scavenging effect which is often detrimental to a supercharged engine. Yes, I said detrimental.
Backpressure is never good. But velocity and backpressure are components of each other. Velocity=good, pressure=bad. But you can't separate the two so you have to balance them for maximum advantage (or minimum impact if you prefer). This is easier said than done.
Most exhaust "knowledge" is based on natural aspiration. I've never found any qualified research or even enlightened opinions on exhaust systems for supercharged engines. It can be both perplexing and enlightening if you ponder that for awhile.
Generally speaking less is more. Knowing when and how to apply that axiom is the key.


I know that is cryptic, but it is what it is...... :)

Got it :)
So there will always be pressure while keeping velocity
Making an exhaust with the least pressure but highest velocity to where you are at an optimum point would balance the best of both worlds

Miguel5671
06-14-2013, 02:05 PM
The main problem with the stock exhaust is not the diameter of the piping. It is the limits to exhaust flow (velocity) caused by:
Severe bends at converter(s).
Small diameter exhaust manifold outlet
small diameter resonator to exhaust pipe coupling.

Open up the outlet of the exhaust manifolds to smooth the transition into new smoother flowing down tubes with bullet style converters (gutting the stocker still leaves the 90 degree turn), rework the connection to the resonator to remove tubing diameter changes or delete it. That's all I'd worry about until I was pushing over 300hp at the rear wheels.

Yes, because those parts cramp the piping and instead of a 2" pipe it becomes a ~1.5 which chokes it down thats why porting the manifolds and replacing the stock resonator/mufflers as well as gutting catz or using high flow catz helps a ton as ive seen people run 2.25 exhaust systems here with great success thats just .25 " bigger pipe but not its not choked down by restrictive components that create excessive back pressure,
A normal bend causes the 2.5" to become a 2.25
Only a true mandrel bend will maintain (example ) a 2.5" pipe all the way

90sc35thann
06-14-2013, 02:16 PM
Everyone has closely held ideas that aren't necessarily based in science. Being willing to let go of your favorite thing is often where you start making progress.

I'll just give you all a few tidbits based on hundreds, maybe thousands of hours of dyno time.....


As has been pointed out, exhaust systems are of minimal impact on a supercharged engine.
Exhaust back pressure can be very high in a supercharged application, 15psi is actually pretty normal, 25psi is not unheard of. The HP difference between 5 and 25psi is less than you think. The db difference is massive.
Headers are more or less a waste of money on a supercharged engine. There is a good reason supercharged drag cars don't use them. The biggest benefit of tuned headers is the scavenging effect which is often detrimental to a supercharged engine. Yes, I said detrimental.
Backpressure is never good. But velocity and backpressure are components of each other. Velocity=good, pressure=bad. But you can't separate the two so you have to balance them for maximum advantage (or minimum impact if you prefer). This is easier said than done.
Most exhaust "knowledge" is based on natural aspiration. I've never found any qualified research or even enlightened opinions on exhaust systems for supercharged engines. It can be both perplexing and enlightening if you ponder that for awhile.
Generally speaking less is more. Knowing when and how to apply that axiom is the key.


I know that is cryptic, but it is what it is...... :)

I am with you and understand. One question. In past email exchanges you have indicated that the a supercharged engine draws it's air/fuel charge similarly like an NA motor and that the charge isn't forced in, it is drawn in. If the intake charge behaves similarly to an NA motor then why do forced induction engines not benefit from headers, larger exhaust, etc.? You see I do pay attention to things you say. :-)

XR7 Dave
06-14-2013, 03:29 PM
I am with you and understand. One question. In past email exchanges you have indicated that the a supercharged engine draws it's air/fuel charge similarly like an NA motor and that the charge isn't forced in, it is drawn in. If the intake charge behaves similarly to an NA motor then why do forced induction engines not benefit from headers, larger exhaust, etc.? You see I do pay attention to things you say. :-)

It's because overlap and the resulting phenomenon are the key to NA performance and are therefore highly engineered to take maximum advantage of the effect. With supercharging the pressure differential between intake and exhaust during overlap is highly exaggerated and can easily result in overscavenging of the cylinder. If you don't care about fuel consumption or exhaust temperatures then you can mostly disregard this, but for a street engine it becomes a factor of interest, particularly when you are finding that you are maxing out injectors pre-maturely and/or melting cats, etc.

David Neibert
06-14-2013, 03:35 PM
It's because overlap and the resulting phenomenon are the key to NA performance and are therefore highly engineered to take maximum advantage of the effect. With supercharging the pressure differential between intake and exhaust during overlap is highly exaggerated and can easily result in overscavenging of the cylinder. If you don't care about fuel consumption or exhaust temperatures then you can mostly disregard this, but for a street engine it becomes a factor of interest, particularly when you are finding that you are maxing out injectors pre-maturely and/or melting cats, etc.

So my mismatched 1-3/4 primary tubes with a 3" collector may actually be good for something ?

terralex
06-14-2013, 05:13 PM
Serious drag racers run open headers. I don't think it is hurting their torque. :)

Serious drag racers have no considerations beyond red line HP and Torque figures.
Their intakes, heads, valves, CAM(S) and exhaust are intentionally engineered to be as free flowing as possible to hit the highest power numbers at the higher RPMs.

If you think it's optimum for your Supercoupe try putting that engine in and driving through Wendy's for a burger and fries. First thing is does your tank even hold enough fuel to get you there ?? Can you make it back without refueling ?? Any chance they can hear you over the exhaust and engine noise ?? Will it load up and die at each stop light and if it does will it be so badly flooded you can't clear it out and need a tow ??

Do you care if it idles under 2K ?? Do you care if it idles smoothly at 1K ??
Do you care if it get's less that 3 miles per gallon ??

Somewhere between grandmothers grocery getter, like my Volvo 850 wagon and that dragster with 1 foot long individual tubes on the exhaust ports is a ton of engineering. On the stock car back pressure is needed as it's designed to have it and it works with the cam. It's designed, engineered with exact lift and overlap in the cam to compliment the intake, combustion chamber design and exhaust to give a combination of the best mediocre power, reliability, emissions, fuel economy, driveability, cheap manufacturing and assembly possible and back pressure does figure into that.

It isn't a yes no question. It depends on everything you've done or haven't done to you engine, intake and exhaust and exactly what you want to achieve and more importantly what you're willing to give up getting there.

On a stock or slightly modified engine reducing the back pressure to near zero can negatively impact the driveability and performance. If you've changed the cam or cam timing then it's a whole new ball game and only a dyno is going to know for sure.

90sc35thann
06-14-2013, 05:28 PM
Serious drag racers have no considerations beyond red line HP and Torque figures.
Their intakes, heads, valves, CAM(S) and exhaust are intentionally engineered to be as free flowing as possible to hit the highest power numbers at the higher RPMs.

If you think it's optimum for your Supercoupe try putting that engine in and driving through Wendy's for a burger and fries. First thing is does your tank even hold enough fuel to get you there ?? Can you make it back without refueling ?? Any chance they can hear you over the exhaust and engine noise ?? Will it load up and die at each stop light and if it does will it be so badly flooded you can't clear it out and need a tow ??

Do you care if it idles under 2K ?? Do you care if it idles smoothly at 1K ??
Do you care if it get's less that 3 miles per gallon ??

Somewhere between grandmothers grocery getter, like my Volvo 850 wagon and that dragster with 1 foot long individual tubes on the exhaust ports is a ton of engineering. On the stock car back pressure is needed as it's designed to have it and it works with the cam. It's designed, engineered with exact lift and overlap in the cam to compliment the intake, combustion chamber design and exhaust to give a combination of the best mediocre power, reliability, emissions, fuel economy, driveability, cheap manufacturing and assembly possible and back pressure does figure into that.

It isn't a yes no question. It depends on everything you've done or haven't done to you engine, intake and exhaust and exactly what you want to achieve and more importantly what you're willing to give up getting there.

On a stock or slightly modified engine reducing the back pressure to near zero can negatively impact the driveability and performance. If you've changed the cam or cam timing then it's a whole new ball game and only a dyno is going to know for sure.

Huh? You are taking something I said figuratively to explain a point and took it way too literally.

TinManSC92
06-14-2013, 10:44 PM
Yah! But, He's so right. lol
And besides....no one has mentioned why are cats came in the size they were initially produced with. that is a very important element to leave out of the question of design
The static pressure method of design instead of the straight velocity method matters with our emission laws.

90sc35thann
06-14-2013, 11:23 PM
Yah! But, He's so right. lol
And besides....no one has mentioned why are cats came in the size they were initially produced with. that is a very important element to leave out of the question of design
The static pressure method of design instead of the straight velocity method matters with our emission laws.

What's right? That I can't drive my SC through a Wendy's drive through with a 5,000 HP top fuel engine under the hood?

If so now my entire plan is out the window. :)

I won't comment on the rest as I am still shaking my head.

BTW - Cost had much to do with the lack of efficiency of our factory exhaust systems. Just ask any of the guys running a custom aftermarket exhaust system with high efficiency cats. I am pretty certain they are still passing the emission tests.

Miguel5671
06-15-2013, 01:40 AM
What's right? That I can't drive my SC through a Wendy's drive through with a 5,000 HP top fuel engine under the hood?

If so now my entire plan is out the window. :)

I won't comment on the rest as I am still shaking my head.

BTW - Cost had much to do with the lack of efficiency of our factory exhaust systems. Just ask any of the guys running a custom aftermarket exhaust system with high efficiency cats. I am pretty certain they are still passing the emission tests.

I think He is right on this one ford was over the budget actually they started using a couple cast crankshafts but then had to upgrade to the forged crank because they saw it was a mandatory thing to have other than that sole reason they would have used cast to keep production $$$ down also the exhaust they wanted to make sure not to out power their precious pony car and I believe this is true to keep budget and price down

THey never admited
But they did admit that when the 4.6 was first introduced they kept the power equal to the 5.0 on previous year to not make the popular 5.0 look bad

They did it on that case I wouldnt even doubt twice they would keep the SC down on power and production price

They saw lots of potential in the SC so they wanted to do tge SVE (termi motor) but they probably thought "wait a minute how will our pony car out perform this ?" So they ditched the SVE bird so thst they could use that potential in a pony car which was 03/04

ANd hell those terminator cars are Mean as hell...

BTw yes u can drive a track car not to Wendy's but I drove to whataburger the other day had NO other working vehicle lol u will get stopped I did twice in the way but I got away with warnings cops were quite nice that time


THis is the vehicle I drove to whataburger too about a 6 mile trip hehe

It was a pain in the ~~~ being its a track truck no PS no alternator electric water pump just 2 optimas that wont last very long lol
It has s 12 gallon fuel cell and even if I get 1 mile per gallon :p I would have made it plus I looked like s total boss (btw it gets like 5-7mpg) but de tuned should do more

https://www.youtube.com/watch?v=W2l9RyfoKSM&feature=youtube_gdata_player



Thought id share some pics full resolution was too big :/ didnt let me upload them full size

So sarcastically yes u can drive a track car with blower with huge cam with open longtubes :D

terralex
06-15-2013, 03:18 AM
Huh? You are taking something I said figuratively to explain a point and took it way too literally.

It's not personal it was just a good line to quote to open up on the thread.

It's the idea of saying because a race engine runs open headers or just pipes and it doesn't seem to hurt their torque (or power). But it does hurt a lot of other parameters like idling, off throttle response if there even is anything at off idle, midrange torque and noise. They all affect basic driveablilty and although my SC is pretty much a lurker in the garage most of the time I like to have it smooth and able to accelerate crisply from 25 MPH without having to worry if I'm spinning enough R's to be in my limited power band.

But realistically it is true. Open headers have their place and so do stock cats. It's a matter of knowing what you want and what combination of parts will get you there. The big thing is what are you willing to give up to get what you want. The more power you go for the narrower the design and operating parameters become and soon you have a trailer queen (a very powerful trailer queen;))

I guess the short answer I could have said is no restriction is good for a real race engine that's built for it but if you're stock or close to stock you can't use that as an example to say no restriction is better or ok for everyone. Stock or slightly modified are designed for a certain amount of back pressure and some (I've seen it happen) run like crap if you take it all away.

I'd rather have a "Big Dog" exhaust on my SC but I just don't see that much of a gain for the limited modifications I've done to it.

On the other hand I have a turbo 850 2.3 with a bigger turbo, 3" downpipe, catless and 2.5" SS exhaust.

Then there's the 83 RX-7 with a chev 454 running headers with a custom 2 into one 3" into a 40 series flowmaster and all you see at the tail end is a chrome 3" turn down that looks like a fart can. And it is quiet enough to take through a drive through. :D

Each one is different because they are different in every respect. You need to look at the package and not just slide under the car and cut off the cat and muffler and think you're going to go fast.

terralex
06-15-2013, 03:36 AM
"That I can't drive my SC through a Wendy's drive through with a 5,000 HP top fuel engine under the hood?"

Or are you are taking something I said figuratively and twisting it and adding 5,000 horses to it ?? I never said you couldn't.

You've had time to shake your head but what is it I said that doesn't make sense ??

As for our stock exhaust ... since it's such an improvement to the cars performance no matter what you do to it I'm guessing they designed it poorly to keep the Mustang out front as the higher performance model. They sold more of them and they saw our numbers declining.
The nice thing is you can get a lot of bang for the buck opening up our exhausts.

"So sarcastically yes u can drive a track car with blower with huge cam with open longtubes"
What I was saying is that it isn't optimum. Check out youtube for crazy people doing crazy things in drive throughs, your's is tame.

90tbird4.7l
06-15-2013, 03:42 AM
Here is a chart for exhaust sizing http://www.allfordmustangs.com/forums/attachments/5-0l-tech/90293d1265774832-exhaust-diameter-tuning-exhaust-size-tuning-guide.jpg

Miguel5671
06-15-2013, 03:48 AM
"So sarcastically yes u can drive a track car with blower with huge cam with open longtubes"
What I was saying is that it isn't optimum. Check out youtube for crazy people doing crazy things in drive throughs, your's is tame.[/QUOTE]

We know it isnt optimum other wise cars would come that way from factory, and theres a reason they dont because they are street cars not track machines
Yet theres street legal 8 second cars that people still drive on the streets and they are loud how they keep them street legal idk

This truck isnt street legal anymore its a track only vehicle that sees high 8 sec- low 9 sec 1/4 mile of course I know it isnt optimal I didnt say mine was the craziest deal either


"If you think it's optimum for your Supercoupe try putting that engine in and driving through Wendy's for a burger and fries. First thing is does your tank even hold enough fuel to get you there ?? Can you make it back without refueling ?? Any chance they can hear you over the exhaust and engine noise ?? Will it load up and die at each stop light and if it does will it be so badly flooded you can't clear it out and need a tow ??"

My point is with a track engine driving to get a burger and fries
Enough gas ? Yes
Re fuel ? No
COULD they hear? They got order right so yes
DIe at every stop ? No
NEed a tow ? No

It is not optimal but not impossible to or horribly bad to where u gotta trailer queen it.

Miguel5671
06-15-2013, 03:54 AM
Lol I love how much this thread deviated from the original question lol

90tbirdsc
06-15-2013, 04:17 AM
Lol I love how much this thread deviated from the original question lol

Yes lol, I still don't really know for sure if my exhaust is to free flowing for the stock heads and cam:confused:

90sc35thann
06-15-2013, 06:51 AM
LOL. Not upset at all. That's why the smiley face. I probably should have put more of them on there and text sucks at conveying messages. I had a good laugh over it.

Sorry man. Was shaking my head as the Wendy's drive through was funny.

You are right. There is much that goes into determining what exhaust is the ideal size.

Let me just say this and I don't mean to hurt any feelings.

We can all agree that the stock exhaust sucks. We can all agree the ideal exhaust size is somewhere north of where it is from the factory.

The truth is that even a good 2.5 inch exhaust system with headers is going to offer some level of back pressure. Even a 3inch system will.

The real question is IMO what is the right size. Dalke's post makes a lot of sense. It would be very interesting to see dyno results on a setup with headers and exhaust vs. ported manifolds and stock exhaust. That unfortunately is way more work than simply swapping out a different SC. LOL

I don't know. Still like Dave said, there is a part of me that just isn't ready to let go of the fact that headers are a waste of time on these cars.

I look at our stock manifolds and they just, well, look wrong. LOL

I look at our stock exhaust system and, it as well, looks just plain wrong. LOL

As straight through as my exhaust system is today, it still provides back some level of back pressure, albeit less than it was previously.

Is it hurting my HP and torque numbers? I would like to think not but I am not willing to reinstall my old exhaust to find out. LOL

One thing is for certain. To the enthusiast, our modified exhaust systems sound way better than a stock system. :)

Do they help HP? I am not certain.

I do think I recall reading through a post of Dalke,s about a time where he was low on cash and a muffler broke off his cougar and he welded the pipe over as a cheap fix and if I recall I believe he said it didn't hurt performance at all. It's been a while since I read the post so I may be off.

So maybe a single exhaust on our cars wouldn't mean a hill of beans difference. LOL

Miguel5671
06-15-2013, 07:57 AM
LOL. Not upset at all. That's why the smiley face. I probably should have put more of them on there and text sucks at conveying messages. I had a good laugh over it.

Sorry man. Was shaking my head as the Wendy's drive through was funny.

You are right. There is much that goes into determining what exhaust is the ideal size.

Let me just say this and I don't mean to hurt any feelings.

We can all agree that the stock exhaust sucks. We can all agree the ideal exhaust size is somewhere north of where it is from the factory.

The truth is that even a good 2.5 inch exhaust system with headers is going to offer some level of back pressure. Even a 3inch system will.

The real question is IMO what is the right size. Dalke's post makes a lot of sense. It would be very interesting to see dyno results on a setup with headers and exhaust vs. ported manifolds and stock exhaust. That unfortunately is way more work than simply swapping out a different SC. LOL

I don't know. Still like Dave said, there is a part of me that just isn't ready to let go of the fact that headers are a waste of time on these cars.

I look at our stock manifolds and they just, well, look wrong. LOL

I look at our stock exhaust system and, it as well, looks just plain wrong. LOL

As straight through as my exhaust system is today, it still provides back some level of back pressure, albeit less than it was previously.

Is it hurting my HP and torque numbers? I would like to think not but I am not willing to reinstall my old exhaust to find out. LOL

One thing is for certain. To the enthusiast, our modified exhaust systems sound way better than a stock system. :)

Do they help HP? I am not certain.

I do think I recall reading through a post of Dalke,s about a time where he was low on cash and a muffler broke off his cougar and he welded the pipe over as a cheap fix and if I recall I believe he said it didn't hurt performance at all. It's been a while since I read the post so I may be off.

So maybe a single exhaust on our cars wouldn't mean a hill of beans difference. LOL




This does sound like a topic that could be argued for years lol because we probably won't test a stock exhaust system after we go our custom one

And also because it is a complex one
It shifted from being right or wrong to back pressure to right velocity to scavenging effect to NA vs FI engines to proper size many variations

But id like to think it helps theres an article on muscle mustangs and fast fords of a 1990 tbird and the exhaust improved Somewhat
Heres the link

http://www.musclemustangfastfords.com/tech/mmfp_0707_1990_thunderbird_super_coupe/viewall.html


So since its worked before quite successfully the most common set ups is around 2.25-2.75 in dual pipes and single pipe 3-3.5
Mufflers X, H, Y pipe and resonators are a matter of sound preference mainly

Why reinvent the wheel ? :p
If the knowledge is there already we should use it to our advantage

90sc35thann
06-15-2013, 08:56 AM
It would be great if someone could get a Ford/Mustang mag to post an article regarding where the SC's are today and the avialble mods in today's world and go through a similar exercise.

I'll bet the Ford community would be shocked.

XR7 Dave
06-15-2013, 09:39 AM
The MM&FF article was less than factual. Most magazine articles are.

90sc35thann
06-15-2013, 09:56 AM
The MM&FF article was less than factual. Most magazine articles are.

True to that Dave! I try and be careful of thins that get published and use some good common sense. I learned printed material isn't always correct at a young age. For example when Ford only rated the Boss 429 Mustang at 375HP. That was certainly not accurate.

Miguel5671
06-15-2013, 02:35 PM
Yea they have to sugarcoat things a lot. Part of advertisement

90tbirdsc
06-16-2013, 09:07 PM
Has anyone ever LS swapped a thunderbird with a t56?

Miguel5671
06-16-2013, 09:11 PM
Has anyone ever LS swapped a thunderbird with a t56?

I Know of 2 people doing that with an LS motor and trans
One is on a 95 5 speed LS turbo build
The other on an 89 5 speed just NA LS1 swap

90tbirdsc
06-17-2013, 02:44 PM
I Know of 2 people doing that with an LS motor and trans
One is on a 95 5 speed LS turbo build
The other on an 89 5 speed just NA LS1 swap

Could you get any pictures?

sc91gt
06-22-2013, 10:48 AM
It is known our cars, as with most boosted cars need a more free flowing exhaust. But too open and torque drops off. With smaller displacement, (v6,I4), it is more noticeable. A v8 has the same amount of torque in NA form so it doesn't rear its head as noticeably. Completely open exhaust is for high rpm HP on built motors. SC's are not normally high rpm cars.They need that low end torque to get their heavy asses moving.:) The guy who did the exhaust on my supercharged 91 mustang 11yrs became one of my best friends.So I have spent countless hours at his shop learning and working on all manner of cars.I am not an expert and won't pretend to be, but in my slightly educated opinion your exhaust is too open even for a modified motor.
Yes lol, I still don't really know for sure if my exhaust is to free flowing for the stock heads and cam:confused:

terralex
06-22-2013, 01:56 PM
"dual 2.5 exhaust off the manifolds to single 3 behind tranny and dump, could that exhaust be a issue? Should I run it to the back of the car and put mufflers on it?"

Without a cam I would guess that you have more exhaust than your engine needs.

I would add the mufflers for both sound and to have a more balanced exhaust that would likely work better with the engine (cam) throughout the power band.
Without a dyno it's mostly guess work on how much is enough and how much is too much. I'm thinking it's great for WOT but it's likely too much to develop the maximum torque in off idle and mid-range.
But again, we can fight about it but the only answer is to actually run it up on a dyno and do you care ?? Do you care if you might be loosing some mid-range to have the max WOT and are you going to cam it in the future ?? Do you care about the noise or is noise what you're after more than power.

Miguel5671 said it early on,
The motor needs a bit of back pressure from the exhaust
But not as much as it had stock
However something like dual 3" exhaust would be complete Overkill
Stock catz are a restriction
Stock resonator is biggest restriction
Stock mufflers not so much but yes
Port ur stock manifolds that will also help

Myself, I'd hate the drone and that would drive me to put a muffler or two on it. The other thing I'd do on a modified engine is go with headers. I've read a number of postings saying they aren't worth it but I've never seen an engine that didn't flow better with a good set of headers.

XR7 Dave
06-22-2013, 02:10 PM
You guys crack me up.

At 400rwhp switching from stock exhaust manifolds to Kooks headers results in less than 5rwhp on the dyno. Going from a full exhaust with cats, resonator and mufflers to wide open headers results in about 8rwhp on the dyno (also at the 400rwhp level).

You don't need back pressure. Ever. You need velocity. Velocity does create back pressure but there is a big difference.

Stock cats aren't much of a restriction at all. I've made 300rwhp through the stock cats more than once. Going to high flow/big downtubes never helps anything.

My current car makes 380rwhp (on pump gas and on the "Dream Crusher Dyno") through stock manifolds, 2.5" cats, resonator, and mufflers. It's quiet enough on the highway that you can hear the lifters ticking happily along.

Dumping the exhaust early is not a problem. Having too big of pipes for your HP level is a problem. For internally stock engines anything bigger than dual 2.25" or single 3" is probably hurting velocity to the point that it is costing low/mid range response. On a modified engine anything bigger than dual 2.5" is a waste of time and probably noisier than it needs to be.

Hock
06-22-2013, 02:13 PM
This is what I have"

Ported Manifolds

"Test Cats"

Full 2.5" mandrel bent exhaust w/x pipe:

http://www.mandrelexhaustsystems.com/servlet/the-116/92-dsh-97-THUNDERBIRD-EXHAUST-TUBING/Detail

http://www.mandrelexhaustsystems.com/servlet/the-317/89-dsh-98-FORD-fdsh-LINCOLN-fdsh-MERCURY-RETROFIT-X-dsh-PIPE/Detail

2 Summit racing 12" glasspacks:

http://www.summitracing.com/parts/sum-630805/overview/

2 Dynomax Ultra Flow mufflers:

http://www.summitracing.com/parts/wlk-17219/overview/

I would say its alot of airflow and virtually no back pressure. I have absolutely no problem with torque according to the dyno at 370ft/lbs at the wheels. There is a bit of drone at cruise which I will be fixing in the future before I put the car back on the road.

Here is what it sounds like on the dyno, you can just hear it over the blower whine and dyno hum.

http://www.youtube.com/watch?v=KKMAE8QuVf0&feature=share&list=UUsuIwsnChA3CE9CojG1hFhQ

Miguel5671
06-22-2013, 02:30 PM
You guys crack me up.

At 400rwhp switching from stock exhaust manifolds to Kooks headers results in less than 5rwhp on the dyno. Going from a full exhaust with cats, resonator and mufflers to wide open headers results in about 8rwhp on the dyno (also at the 400rwhp level).

You don't need back pressure. Ever. You need velocity. Velocity does create back pressure but there is a big difference.

Stock cats aren't much of a restriction at all. I've made 300rwhp through the stock cats more than once. Going to high flow/big downtubes never helps anything.

My current car makes 380rwhp (on pump gas and on the "Dream Crusher Dyno") through stock manifolds, 2.5" cats, resonator, and mufflers. It's quiet enough on the highway that you can hear the lifters ticking happily along.

Dumping the exhaust early is not a problem. Having too big of pipes for your HP level is a problem. For internally stock engines anything bigger than dual 2.25" or single 3" is probably hurting velocity to the point that it is costing low/mid range response. On a modified engine anything bigger than dual 2.5" is a waste of time and probably noisier than it needs to be.

I agree no back pressure is needed but there will be some backpressure to keep optimal velocity on the exhaust like u said they are relatives and one comes with the other so the system for most of the SC applications will have some backpressure,

maybe I worded that wrong saying the motor needs a bit of back pressure what i should have said is the motor needs the right velocity in the exhaust system which by all means will have some back pressure.

I Think if one really wanted to have both worlds as to no back pressure for the high rpms and the low end mid response is to have a suited exhaust system say for example ported manifolds 2.5 downtubes with cats or without a resonator or x pipe etc and mufflers that will have say 1-4psi back pressure just made up numbers as compared to stock 10-15psi thats already a big improvement in getting rid of back pressure aside that

To have no back pressure while keeping that exhaust would be having dual electric cut outs after the down pipes

Keep the cut outs closed on daily driving and open them on the track or dyno if it even matters
And I say these would be minimal gains but if someone wanted them I think thats how both arguements of keeping velocity and little to no backpressure would come to be

And even so say at 400rwhp like u said the gains are 5-8rwhp which is not worth the hassle

madcharger
07-07-2013, 08:46 PM
I have to agree with Miguel on this one...all out race cars leave the line with a lot of revs..and even zoomie headers have some resistance for the volume of exhaust that is exiting...oversize pipes hurt velocity, and low end torque will suffer..the diameter and length of pipe matters more then people think..on a smaller engine, such as a motorcycle, a few inches more or less is more noticeable.. just my .02

ganuolfthegrey
07-20-2013, 01:27 PM
here is mine stock manifold's ported. gutted cat's into flowmaster 40 with 2.5 mandrel bendz exhaust kit. duel exhaust from front to back. http://www.facebook.com/photo.php?v=637448359599249

shoalcracker
07-20-2013, 10:21 PM
Jason

Sounds great.

Congrats on a mumber of fronts.

Paul

shoalcracker
07-20-2013, 10:45 PM
Anybody offering this.

Paul

http://www.youtube.com/watch?v=tsvOW_NrdY8