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View Full Version : Whats good for increasing high RPM power?



CaifanSC
05-05-2005, 07:18 PM
I hope nobody says turbo either :D ! (that comes laterz). Anyways the reason i ask is b/c i raced a friend of mine with a 90 SHO. It has cone filter, ported TB, MAF, and a few parts in the intake manifold, plug wires, chip, and exhaust. You can see what i have in my sig with the exception of a MAC intake, IC fan and very bad 3rd and 4th synchros :p . Anyways, we went from a stop and i got him good...saw his lights pretty far in my mirror....but around 90mph he was not only with me but passing me. By then i was about to (try) shift into 4th and he said he was still in second gear!! I've come to admire and love those DOHC's!

Anyways, my question is...what would increase upper rpm power? Now, ofcourse i know a free flowing exhaust will do marvels, but besides that whats good? Im tempted to think that the long lists of modifications available for our engines are focused in increasing that higher rpm powerband since down low we have no worries...but im not sure, hence i ask.

007_SuperCoupe
05-05-2005, 08:42 PM
Just took a look at your member page...You don't have many mods to this point. High rpm power is something that you are not totally ready for at this point. I think what you are looking for is increasing your power band over the whole range. All I can say is to be prepared to spend some money. You can check my member page for my mods. I've got about $4400 invevsted in performance parts as of now, and I haven't tackled the high rpm power woes yet. I have actually taken my SC about as far as I can go for now without getting into the high rpm power makers. First and foremost is heads and cam. Those 2 things make a huge difference in power on the high end. Right now the exhaust ports aren't shaped properly for good high rpm power. Good porting, plus a matching cam can take care of that. Also the AR supercharger swap will increase your powerband up high as well. However, you will still be restricted by your head flow.

I'm not going to sit here though and tell you the best way to get this power is "XYZ" though. I'm simply making an observation and giving you my opinion on what you might want to consider doing. FWIW, I dyno'd 250 rwhp and 340 rwtq with my mods. My next step engine wise will be the heads/cam and AR for power. I have everything else in place to make the most of those mods. Take it for what it's worth. I'm just giving you an example of what I've done that has worked well for me.

CaifanSC
05-06-2005, 01:53 PM
Sam...that makes sence. I am nowhere near needing high rmp power...yet, but after my experience with the SHO i started wondering about it. All of us know that our cars are killer at low end b/c of the m90...but also b/c of the m90 power is reduced after a certain point in the curve.

I guess what i got from your message is that most of the mods we have available now sort of extend the power and efficiency of the m90...sort of prolonging our 'lower end' power and yet still have upper rpm possibilities? Like the AR...on that note, since its apparently in ur near future, how much are you looking to spend on the AR conversion?

J57ltr
05-06-2005, 02:11 PM
Upper RPM power is not what the 3.8 was meant for it you notice at all the dyno charts most of them rarely exceed 5500RPM The SHO is s Yahmaha engine and can go to about 9K with cam mods and some short block fortification.

The 3.8 is a grunter as said before you need to make a broad power range. To make more power up higher you need to shift the torque band higher (cam timing), but the stock roller lifters pushrods, valves, retainers and springs are heavy and aren't meant for high RPM use. Besides the higher you ring it the faster it wears out.

Jeff

007_SuperCoupe
05-06-2005, 11:16 PM
Sam...that makes sence. I am nowhere near needing high rmp power...yet, but after my experience with the SHO i started wondering about it. All of us know that our cars are killer at low end b/c of the m90...but also b/c of the m90 power is reduced after a certain point in the curve.

I guess what i got from your message is that most of the mods we have available now sort of extend the power and efficiency of the m90...sort of prolonging our 'lower end' power and yet still have upper rpm possibilities? Like the AR...on that note, since its apparently in ur near future, how much are you looking to spend on the AR conversion?

I'm no where near the AR yet. I just dropped about $1k to get my car to the point of a tune, so the wife would be pretty upset if I went the next step and got the AR! I need to back off the car modding for a while. ;)

You did gather the right information from my post. You want to start with some other mods to increase your overall power. Once you get to a certain level, (heads, cam, performance rebuild...) you'd be able to pull 7-8k without too much of an issue. But most SC's make power to 6k after heads/cam. If you want a starting point, take a look at my mods. It's not the fastest way or the cheapest way to get to power, but it is solid. It's an example of something that has worked for me. Others have other things that have worked as well. I'd recommend that you find out where you want your car to be. Once you have that in mind, make a plan on how to get there. My end plan includes the AR and heads/cam. At this point, I have only to install larger injectors and I'm ready for those mods. I started out without a plan and ended up with a couple parts that I probably would not have gotten once my plan went into action. Be patient as well. Don't think that you have to go fast now. I've been working on my SC for 3 years now. (Well, my '89 for a couple, then everything got moved to my '92 in the last year.) And I'm finally at a point where I can just drive and enjoy my SC for a while. Make a plan and a good route to get to where you want to be. If you want, I can list how I've made my mods (in order) to show the progression of my mods.

J57ltr
05-07-2005, 12:01 AM
There is no way you are getting 7-8K out of an SC engine, just look at the highest HP list. You will float the valves or spend big money on Ti valvetrain parts and a solid lifter cam, some light weight pistons and solid rods.

Jeff

AsScLoWn
05-07-2005, 01:44 AM
I see the problem here, its fairly simple, yank the hood cable on the SHO from the fender liner and connect the lines from the IRC solenoid or whatever(dual runner intake) straight to vacuum? or is it absence of vaccum :confused: , whatever, not my problem, whatever keeps the butterflies for the shorter runners closed, this should limit his high RPM capability and give your slower car a much needed break against his well engineered powerplant :) . ITS ALWAYS ME ME ME ME ISNT IT, you have to think of the other guys :rolleyes:

007_SuperCoupe
05-07-2005, 03:00 AM
There is no way you are getting 7-8K out of an SC engine, just look at the highest HP list. You will float the valves or spend big money on Ti valvetrain parts and a solid lifter cam, some light weight pistons and solid rods.

Jeff

If built right it will handle that rpm....Problem is that no one really builds it to handle that... There's a notion out there that these engines don't make any power above 5500 so there's not much done beyond that. It's true for the M90, but not so for the AR. It's only time until someone makes an engine that can handle 8k.

Smoof
05-07-2005, 07:48 AM
I think no matter what you do really, you wont take a SHO in the top-end. Before I go any further, I'm calling BS on your buddy! SHO's 2nd gear tops out at 67MPH at 7500RPM (I had a SHO MTX with a 3.2L swap), third gear will top out around 107-110ish at 7500RPM.
SHO's pull VERY well in the top-end due to those snakes. I think no matter what you do, you'll have trouble taking a SHO in the topend. When I had my SHO, I had the thing up to 120 and still pulling hard. My SC, the fastest I've had it up to was 110 (with mods in my sig) and after about 90mph or so, I could tell the SC didn't have anywhere near the pull the SHO did.
That's why those SHO bastards always want a roll race. Just fight em as much as you can into a deadstop.

Randy N Connie
05-07-2005, 08:00 AM
To get more RPMs,you need more air.
Open up the IC & intake system after the blower.

I have no problem in pegging the tach
with a stock motor with bolt-ons.

You just need to make the parts.

Randy

J57ltr
05-07-2005, 09:47 AM
If built right it will handle that rpm....Problem is that no one really builds it to handle that... There's a notion out there that these engines don't make any power above 5500 so there's not much done beyond that. It's true for the M90, but not so for the AR. It's only time until someone makes an engine that can handle 8k.

You can do anything with enough money, but the fact remains that the engine isn't made to handle that kind of stress. If you want to rev it that high it's going to take a LOT of money the type of forced induction is moot. Like I said before you will need strong rods light weight pistons and a valve train that is second to none. It's not a notion it's physics plain and simple.
Let's just make a set of DOHC heads for a obsolete design that is not very popular, that makes sense. :rolleyes:

To make a 3.8 that makes power to 8K on a regular basis,you will spend about 200 times what the car could ever be worth. 6.5K is about the limit I would ever go on this engine it just doesn't make any sense to go to 8K. With a cam to support level you would end up with a 2K idle.

Jeff

CaifanSC
05-07-2005, 12:50 PM
To get more RPMs,you need more air.
Open up the IC & intake system after the blower.

I have no problem in pegging the tach
with a stock motor with bolt-ons.

You just need to make the parts.

Randy


Hey Randy, i was under the impression that you COULD peg the tach (whenever it gets there) but after a certain RPM it just doesnt make more power enven if it revs out more.

Randy N Connie
05-07-2005, 02:09 PM
Its a fact, one of the biggest reasons that the SC 3.8 bird motor
makes power down in the lower RPM Range,Or any motor is.

Short or no runner manifolds will make power in the lower RPM range.

If you want power to be made higher up the RPM range ,on any motor
be it carbuator,supercharge,turbo,3.8 SC you want a manifold with long or longer runners.

Thanks

MIKE 38sc
05-07-2005, 03:39 PM
Randy is it possable you just made a mistake and got that backwards about intake runner lenght?

92bird
05-07-2005, 04:49 PM
you are all overlooking one very important thing.. Gearing!

A 94-95 5 speed with the factory 2.73 gears is pretty damn tall.

My first mod back in '99 was a set of 3.27:1 gears to my '92 5 speed.

With only the gear swap, k&n panel air filter, and removed silencer, I was consistantly about 2 carlengths ahead of a friends SHO from a 0-100 mph run.

The SHO has a lot shorter gearing, but doesn't have the torque of the SC off the line.. Basically the SHO has to play catch-up, and if your SC has stock rear end gears and no serious mods, the SHO will catch up. But for the stoplight to stoplight races (which are 90% of my encounters anyway), the SC owns the SHO..

Randy N Connie
05-07-2005, 06:39 PM
Mike yes I did go backwards.I think I will go eat another pain pill. :)

But are manifold, intake system is one reason that we have the low power band to RPM.

Thanks Randy

MIKE 38sc
05-07-2005, 07:32 PM
LOL!!!!! I was pretty sure you just got mixed up on that. :)
I agree with you the stock SC's intake is so restrictive its kinda irelavent if it has any port runners or not. :( if not for the blower this motor is a slug.
What could be learned from this and how should we apply that knowledge?

Jason Wild
05-07-2005, 09:16 PM
has any one made there own lower intake I was looking at making one in my free time.

Randy N Connie
05-07-2005, 09:25 PM
Mike
They are many things wrong with the intake & the system in front of it.
The biggest reason why we stop making power above the 5000 RPM
range .Is the motor runs out of air.The air entances are to small for
enough air to even enter the manifold.Its not a hugh problem to worry
about flowting the valves,because there is not enough air entering the
stock set up to spin the motor fast enough.

I think it would take a book to write about are manifold flaws,If you want
to nit pick and go over ever little tid-bit.There are just so many reason.
why Ford did this & and that.And the physics of the end results.
There would be chapters for topics of the engieers,top dogs,bean counters
flow charts,physics,hood heigth,it would just go on and on.Why it is.

I can set down and talk and make since.But I am a pisspour comunicator
on line.

Are manifold is a plenum with six holes in the side of it.With no runners
I don't think a triangle in the center could be called a runner,air vain yes.
It is impossible to get much if any straight air flow to the ports.I think
if a person spent some time on developing air-vains would be of help.
But this is not easy with the room avalible in are designed manifold.
I have thought of adding a wall down the center of the manifold.With
directional vains leading to the ports.But this will create other problems
to be worked around.But this may be one way to raise the rpm power band.

Air flow is just like a car on the hole.You fix one problem.
then five more problems pop up that need to be delt with.

No one is going to take or spend much time to fix some problems with the SC.
Sc people either do not understand the the time & expense it takes to
make a pre-designed part better.Or even a new part,They flat don't care,or are to cheap,,,These people are there own worst enemies.when it comes to ever getting any parts.I have been doing parts most of my life.This group of bird people are constantly cutting there own throats when it comes to aftermarket parts.I have never
seen anything like it.A chevy bunch of Chevy guys could not do a better job.
to kill a parts market for thuunderbirds.

The post on this board are funny all the time.You read one post of whinning
about power.The next post consist of bashing.The next post talks about
some nice part someone is spending time and money on for others.The next post has pictures of cheap unfinished look alike junk parts stolen parts from the last post.

I am sure Iv made somebone mad again posting the truth.All I can say is
That when I die.I am going to be buried face down,So you can still kiss
my ***. :)

THANKS RANDY

Randy N Connie
05-07-2005, 09:34 PM
has any one made there own lower intake I was looking at making one in my free time.

I have one,I think Mike has.And some SC 3.8 stang people have.I doubt that many will ever see them though.

Jason I got my brake lines finish.

Thanks Randy

J57ltr
05-08-2005, 02:02 PM
Back to the original discussion. The intake manifold has not a lot to do with high RPM in this case.

If I were to drop a tunnel ram on a stock engine would I be able to make power at 7-8K? No I wouldn't because it takes more than one part to make power and shift a power band. Cam timing is one of the largest things that affect power band, Cylinder head flow among others. Anyone ever hear of valve float? Do you even know what it is? With the heavy valve train parts Valve float will always happen with the stock parts you will never make it over 6.5K. The difference between 6K and 7-8K is huge when it comes to the enignes durability. The engine and car must be built as a system. period.

Jeff

Randy N Connie
05-08-2005, 02:15 PM
I wonder why mine changed with only the swap of moded manifold-plenum.
that only lets more air in.No port changes.On a Stock motor.

The next manifold test.With no more air entering,but with porting.
droped .2 at the track.stock motor.no rpm power band change.

The next manifold-plenum with port work and more air .4 at the track
stock motor the rpm power band went up .

Next test enlarge manifold enlarge plenum,port work not finished testing
but have take over .7 of the time and added 800rpm to the power band.
stock motor.

Jeff I am really interrested in your hands on testing results.I think I
could get some more out of my stock motor with some more
manifold info.

Thanks RANDY

J57ltr
05-08-2005, 07:11 PM
So you picked up 800rpm over stock so you're running 5100rpm? Since I think the stock hp peak of the motor was in the 4400rpm range. I am talking about HIGH RPM 7,000rpm to 8,000. 800rpm gain isn't that high. I have no "hands on" on this exact manifold. The increase you say is not unusual for the modification you listed. But in order to move the power band up you have to change cam timing. All you did was extend your power band.

Jeff

Randy N Connie
05-08-2005, 08:11 PM
Jeff i am just seeing what I can do with the stock heads cam ,ect.
I just got the last manifold on a couple days ago To try out.
I took it back off today.My chip and tune was not good for it.

With a cam ported heads ,tune,ect.It looking up for some good number
in the 6500 plus rpm range,my guesstament.I will find out somday
soon I hope.I am hoping to get the parts on and tuned for the OK
race.Still will be using stock motor then .I hope to get it to pull
good to 6000 rpm.

Its my belief for high rpm power.besides cam,head work,lighter valve train
I would look at some plenum manifold modifications also for caifanSC

Thanks Randy

Jason Wild
05-08-2005, 08:54 PM
Randy,
might you have some pics of this intake and the brake lines. I will only be making this for my self and not selling them. If you dont want to show pics I understand. you can email them to [email protected]

J57ltr
05-08-2005, 11:01 PM
RAndy I agree that the manifold needs work, but my point was that the engine itself is not designed for high RPM so basically without spending a lot of money (even if you did everything yourself) to get it to the rpm ability of the SHO (which I believe the author was going for). Some of the faster SHO's can wring them to 9K to make power. After all torque and rpm are horse power. If you wanted to make a 3.8 go that high (and hold together) it's going to leave you with a stock block, maybe the crank (with work) and the bare heads. Everything else in the entire engine would have to be new and custom to handle that rpm level.

That was my whole point.

Jeff

Randy N Connie
05-09-2005, 12:31 AM
Jeff your right.But he dos not need to turn this big RPM number .
to make the horse power to beat a SHO.

I just listed some of my finding with the intake system.
Now if he adds what your talking about,cam,heads,valve train.
He can research horse power gain number for cam,heads ,ect
And come up with a HP number needed to beat a SHO.
RPM Has nothing to do with who can win a race.Rpms are
for, to know what gear to run to reach max power for the end
of the 1/4 mile.

It does not matter the red line of either car.Of who will win the race.
So a SHO makes 300 rwhp at 9,000 rpm.And a Bird make peak power
300 rwhp at 4200 rpm.You need these number of both cars,for gear ratio,
and the wt. of each car.

I know this is not writtin very plane.I hope you understand
what I am getting at.RPMs alone don't mean quat.Its like
you were getting at in an earier post its a total properly
set up pachage.HP,GEARING TO Weight ratios.Who will
win SHO or BIRD

This is one of the little question that take a book to answer.
I was just tring to answer if you want more RPM you need more
air and fuel.

Thanks Randy

MercsSC
05-09-2005, 08:11 AM
I wonder what would happen ...if you just shorten the stroke down from 3.31in to 3 in ..make it a 205 ci .. 302 is 3 in stoke and gms 302 +283 were both 3 in stroked and they reved really high ..with proper heads and cam ....dave

J57ltr
05-09-2005, 11:46 AM
I wonder what would happen ...if you just shorten the stroke down from 3.31in to 3 in ..make it a 205 ci .. 302 is 3 in stoke and gms 302 +283 were both 3 in stroked and they reved really high ..with proper heads and cam ....dave

You would lose torque and everything else the same (or equal) the power band RPM's would shift higher. Get-r-done with torque. If anything I would stroke the engine to produce a larger engine. Inertia plays a LARGE part when it comes to extreme engine speeds for every oz (28.4grams) the load on the rods is on the order of 5 times as great. That's why the strokes were shortened on the 302 chevy (plus displacment restrictions in racing class). The 302 was a real screamer and was a 350 with a 3" stroke.

Randy I agree that you can beat a SHO with much less rpm capalabity, but the question was posed how do I increase power in that range (compared to the SHO) it's an apples to oranges comparision. that's why I was steering him away from trying to run those extreme rpm levels.

Vernon Cradier has a 91' SC the cam is 218-228 @ .050 and when he put it in I kept telling him that man you are going to have to raise the idle to about 1K and advance the base timing (same thing you would do on any other engine). Well at the time he didn't have the tuner in the car and the thing would barely idle and sounded like a prostocker. I always thought it was way to big of a cam for a small displacment engine (per cylinder). After the tuner was installed and tuned it ran much better. After driving the car it pulled like nobodies business to about 5,600. The car also had kooks long tubes Stan Wodzisz old heads and cam (rumored that he ran low 12's but his GF lost the slip). He is still #19 in the fastest list with a 12.98. (Haven't seen him on the board in a while).

Vernon never ran his car at the track, he wrecked about every corner on the car and started getting rid of some of the parts like his hood. I haven't seen the car in more than a year but I know he hasn't messed with it and it's just sitting.

To me anything over 6.5K is just a waste of time and money to make reliable (as if the 3.8 is).

Jeff

auggystyle
02-20-2006, 03:16 AM
my buddy has a sho and i blast him of the line to about 70 mph then im playing "try and catch the sho". i have over 5k investeded in my bird. everything under the hood is brand new. Its the gearing man. a sho has just about a 4 10 gear ratio over all. and with 7500 rpm redline its a bitch to beat. i hate it. hear i am talking all kind of smack when my car was finally done and a sho takes it out. 2 73 gears are too long range, in the very end i will catch the sho and pass it but were talking 2 miles down the road, and barely passing it. it sucks!!!! but im sure 3 27 like the gears that are in my mustang would crush it. so thats the move you need to make. its the gearing man!!

Kurt K
02-20-2006, 09:06 AM
hmmm, only an 9 month resurrection :rolleyes: :D


Don't take it personally, I'm just refering to a recent trend here on the board.