exhaust mods?

mikey

Registered User
I was going to mod my exhaust this winter and i am starting to gather info on the best way to do it...(for power and sound). I am pretty handy when it comes to work...so I was thinking of Customizing my own!!!

Since i am just a working class fellow like most of us....i think the factory manifolds will do(unless they are cheap enough)...

One question i have is what does the Resonator do? Do i need it..or is it just a piece of junk to restrict the flow? Also can I relocate the 02 sensor wherever on the pipe? Also I am cutting out my cats altogether!!

Another question i have is what size pipe should i use?...

Right now i am pushing about 14 to 16 pounds of boost(from what i hear..that is awsome) So far my current mods are a Hypertech power Module..and a 10% pulley on the blower..and Flowmaster Mufflers,and i took that cheap little air silencer off!!! Those are my olny mods so far!!! Also last spring i rebuilt the top half of the engine...i just got the heads resurfaced and as little taken off as possible!!

Hey....i have also got a Cervini's Ram Air Hood..and i was hoping to put my brain skills to use and maybe this winter i can engineer a project to make it functional...but the best way i figure is to get a different intake manifold..one that is designed for ram air induction(which is probably impossible to fit on the bird)they made these cars so dam tight under the hood, i dunno...but i have checked into other designs from GM and Ford...they say some of there cars have ram air(like the Grand Am).but it isn't true ram air..i gathered that it is more like guided air entry!!! What i am hoping for is the Ram Air like they had on the Muslce Cars of the 60's and 70's.

I realize the Ram Air is a little far fetched..but hey .. its nice to dream...hehehehe

Thanks to all who Help!!!!!!!!

:D
 
Ram Air and Exhaust Mod

I posted a "Ram Air Works" subject....and all you have to do is put a 4" black plastic drain pipe that will contour itself perfectly to the hole in the stock airbox and can be sealed air tight with some tube sealer.

I experimented with different ways to hang it to the front of the car...and finally have it coming right out the bottom...and in this position it picks up its maximum added BOOST of about 4lbs.

Research on the web (don't have the website at hand) I found said that 90 degree bends to the front would cut down the total flow by about 30%. The ribbing in the pipe is surprisingly only a 5% or so factor in the flow according to this guy who tested it.
But the deal is....how would you go from the scoops to the filter to the TB without some nasty bends....that's the problem.
The pipe to the front is only 1 -90 bend.

You will get a lot of critics on this ram air because there is NO real science to dyno of a car with Ram Air. People have done this by blowing high powered fans into the front of the car but all they may be doing is showing a difference between under the hood high temps and colder air from outside the car.

What I have is boosts going from 7 to just over 11lbs or so in the range of 90mph to 120mph....it's right on the gage....so there's no argument there is free hp coming through. I rely on that kick at 90mph when I'm pullin away from some 745i! I've tested this before and after in high speed runs (of about 1 mile to 130 to 140mph....and got 10 to 15mph higher top speed.

Regarding the exhaust do it yourself....remove the cats first, then resonator are your biggest gains....and leaving the stock Y pipe back is fine for 300hp or so applications. With the resonator off I found it too loud because I do want to enjoy the stereo...so I went with the SCCOA flow through Magnaflow resonator....but which is difficult to hang. At WOT it is pretty loud but at highway speeds the stereo is OK.

You should go with no cats and no resonator just into the stock Y pipe and see how you like it. You'll definitely like the performance. Then there's a variety of possible add-on low weight glasspacks that might be a possible add-on to cut down on the noise.

It's still my theory that the back 2 mufflers are really the "resonators" because with them off you get a real resonance around 2,200 RPM or so that will leave you with a sick headache after 10 minutes or so.

What I'm dreaming about is someone to come up with an X-pipe that takes the place of the flow through resonator and accomplishes enough extra muffling to get by....but lower weight and possibly extra performance if it's designed right.
 
I"m getting ready to my exhaust as well. And it's been a while since I posted on an exhaust thread, so here's what I'm planning.

Final Product:
1-Ported stock manifolds. They've got a nastly 'lip' inside them that when removed will increase flow. I think these manifolds will handle more than 300 hp. Enough for me.
2-High flow cats or removed altogether
3-dual 2-1/2 into a reversed 3" inlet, dual 2-1/2 outlet Borla XS muffler replacing the resonator
4-Single 3" around the gas tank to dual 2-1/2 to
5-dual single in/out 2-1/2" borla xs mufflers.

A little on the expensive side for the mufflers, but I believe well worth it in the long run. The Borlas cut down dramatically on the drone and still sound good.

Just food for thought. And everyone has their own opinions on exhaust. Take what you want and leave the rest. Maybe this'll give you some ideas.
 
Oh Ya ..this is GREAT!!!

Hi all....Thanks for your opinions and ideas...they are great!!!!!

LOL..one thing makes me sad though...seeing all these Birds done to the tits...and mine is still beautiful...but damm....some of your Birds are just amazing!!!!...Maybe someday!!!

I am pretty sure of what set up i will use and am thinking of just cutting out the cats altogether and resonator too!! Just gonna keep the mufflers(see how i like it)....so would this be enough to free up some flow with 2 1/2 or is 3" the better choice?

One more question though....if I was to go to a 3" set up...do you all think i would lose out on the boost?

Thanks again!!!

Technology is Aswome SOMETIMES!!!!!
 
I wouldn't go with dual 3" if that is what you are talking about. The reason is fairly simple. Backpressure. Backpressure is both good and bad. You do want some, but not a lot. If you were to go with dual 3", you will loose a lot of exhaust velocity which will hinder performance. You want smaller exhaust to keep the velocities high. That allows better scavaging. Unless your car is highly modded, I wouldn't go larger than dual 2-1/2". But that's what I think. Take it for what it is.

Either setup you decide to go with will cause your boost to drop. But don't be confused by this. Boost is merely a measure of backpressure. You free up your exhaust, your boost will drop, but you will be flowing more air. The difference is that it takes less energy to put that air into the engine. By opening up your exhaust you will also loose a bit of low end torque, but will make up for it on the high end. You will notice this a lot more on the low end, especially if your car is close to stock right now.

If you are going to delete the res. altogether, do a "y" into a single 3" back to where it splits back into dual. (unless your car is a '92 and up...then go with an "x" with dual 2-1/2). Be warned, however, that you will have a lot of drone at around 2k rpm. You may be cool with that. I had a friend who had that, but the drone got to him on the open road. Now he has a res again. The resonator will help elimnate that drone. And if you purchase the right one, it will not hinder performance at all.

Good luck with it and let us know what you think of the setup. And let us know 6 months after you get it. I've seen a lot of people change their setup after that time because the 'sound' has changed a little. Or they just don't like the drone anymore.

Just food for thought.
 
Thanks Again!!Yet another Question?

007_SuperCoupe said:
I wouldn't go with dual 3" if that is what you are talking about. The reason is fairly simple. Backpressure. Backpressure is both good and bad. You do want some, but not a lot. If you were to go with dual 3", you will loose a lot of exhaust velocity which will hinder performance. You want smaller exhaust to keep the velocities high. That allows better scavaging. Unless your car is highly modded, I wouldn't go larger than dual 2-1/2". But that's what I think. Take it for what it is.

Either setup you decide to go with will cause your boost to drop. But don't be confused by this. Boost is merely a measure of backpressure. You free up your exhaust, your boost will drop, but you will be flowing more air. The difference is that it takes less energy to put that air into the engine. By opening up your exhaust you will also loose a bit of low end torque, but will make up for it on the high end. You will notice this a lot more on the low end, especially if your car is close to stock right now.

If you are going to delete the res. altogether, do a "y" into a single 3" back to where it splits back into dual. (unless your car is a '92 and up...then go with an "x" with dual 2-1/2). Be warned, however, that you will have a lot of drone at around 2k rpm. You may be cool with that. I had a friend who had that, but the drone got to him on the open road. Now he has a res again. The resonator will help elimnate that drone. And if you purchase the right one, it will not hinder performance at all.

Good luck with it and let us know what you think of the setup. And let us know 6 months after you get it. I've seen a lot of people change their setup after that time because the 'sound' has changed a little. Or they just don't like the drone anymore.

Just food for thought.


So from my understanding is I can successfully have a set up with 2 1/2" piping all the way through...except for where the Resonator was..I will need a 3" Y joint and connect the 2 points of the Y to 2 1/2" coming from engine..and then connect single point of Y running to back of car? ......... Is this confusing?

Picture this Engine
| |
Y
|
/\

LMAO....kinda like that?
 
First off, what year is your car? If it is an '89 thru '91 the exhaust is routed differently than in a '92 and up. The early style will not allow dual 2-1/2" exhaust because it is routed around the gas tank. A single 3" will work very well there and give you good performance. If you have a '92 or up, then run dual 2-1/2's.

And yes, your diagram is right for the early style gas tank. You other option is to put in a late style gas tank when you do the exhaust, but then you're talking more $$.

If you're wondering what it'll look like, get under your car sometime. Instead of the resonator, invision a "Y" and larger piping going back towards the rear of the car. It 'duplicates' the stock setup, but frees up the flow dramatically.

Here's a pic of what the stock exhaust looks like.
 

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And here is the SCP exhaust. This is just an example of using the single pipe back from, in this case, a high flow resonator. This can give you an idea of what you will see. Keep in mind that this exhaust setup is for the late model gas tank, not the early style. So there will be a significant "turn" in the piping as it routes around the gas tank. Hope you get the idea.
 

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>And yes, your diagram is right for the early style gas tank. You other option is to put in a late style gas tank when you do the exhaust, but then you're talking more $$. >

Nothing is simple, but would like to ask.
Is the gas tank swap as simple unbolt old style,
and bolt on the newer style?
In other words are the attachment points at the same location?

Thank you in advance.
 
You'll need a strap from the newer tank...I want to say it is the strap on the pass side, but am not 100% sure. Grab both to save time. Also you want to get one from a salvage yard. Brand new ones are some serious $$. I went to the dealership just out of curiosity and I think the price was around $1600...NO kidding. Just keep in mind though that the new tank means new exhaust. They've got to be done at the same time.

And if you're going to do the tank, it is highly recommended that you change the fuel pump with a better one at that time too. Because to change it later means to drop the tank, and exhaust to get to the pump.
 
Hi Guys

Sorry it took me few days to answer back...really busy!!!!

Hey--those pics are a perfect example.....thank you!!!

Now I am fully understood on what to do!! With the exhaust that is!!
Hey by the way....Sam Malone is an icon for ALL....Especially the way he obsessed about his Vette! And of Course....all the women he had......hehehehe

Thanks again and again.....Your help has been very Educating and will be very useful soon!!!
 
I've seen a lot

of people go all out on the exhaust and I don't think you need to unless you have serious hp. But the biggest point being that from the back of the resonator back is not the real problem....it's the cats and the resonator.

Try this first. Before I put headers on I had a makeshift system which went directly from the stock manifolds to the connection behind the resonator. I unbolted the connection behind the resonator, chopped it back then bought an adaptor and y pipe from car parts and went to the stock manifolds. Wow...suddenly I could do tire smokin burnouts in 1st....real big difference.

You might be satisfied with that...plus the rework of the stock manifolds would help...which I didn't do.

Then as the smartest next investment I'd do the magnaport II and some intake mods...especially cold air/ram air type system.
 
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