Thread: lowering torque by changing exhaust?

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I'm setting up a 350 sbc crate motor to power my little porsche 914. Is there any way to lower the 350ft lbs of torque by modifying the exhaust in any way. The idea torque range for this tranny is around 300 ft lbs. All Two Cents are welcomed.

Also, what is the most quiet Performance mufflers I can get? ( I'm still a newbie with Chevy performance). Thanks

You can kill some of the torque in a motor by going too large on the header primary tubes, but I don't think it's the best way to do it. Choosing a cam with a later intake valve closing point would move the power band up higher and also bleed off some of the compression at low r's. In addition, you might have the cam ground on 112 or 114 degree lobe centers and install it retarded. There may be a better way, but this is what comes to mind right off the bat. Here's a link to cam characteristics:

http://www.co.jyu.fi/~rax/lobe.htm

A simple rev limiter might be the answer.

Originally posted by lybones
I'm setting up a 350 sbc crate motor to power my little porsche 914. Is there any way to lower the 350ft lbs of torque by modifying the exhaust in any way. The idea torque range for this tranny is around 300 ft lbs. All Two Cents are welcomed.

Also, what is the most quiet Performance mufflers I can get? ( I'm still a newbie with Chevy performance). Thanks

i don't know how much dif. it makes, but I used to race modified round track and longer the track the bigger headers we used and shorter collectors. short tracks small headers and longer collectors. you had to do that to keep up. its makes a big dif. in bottom end.

Ives, a rev limiter is used to limit the maximum revs a motor can attain and would have no effect between idle and max revs. Lybones is attempting to kill off some of the bottom end power to prevent grenading his transaxle.

i thought you wanted more bottom end lybones so if you are looking for less i think techinspector1 has said it all. why not just retard the cam that you have.

"why not just retard the cam that you have."

Originally posted by techinspector1
"why not just retard the cam that you have."

by golly i will.

Originally posted by DennyW
Have to think about engine temp heat rise with cam retarding.

awe! get otta here. 2 degrees is all it needs. wont hurt a thing.

Originally posted by DennyW
If it only takes 2 degrees for 50 horse, I'm changing mine right now,

i dont think degreeing the cam changes the HP just move it around.

Originally posted by DennyW
Have to think about engine temp heat rise with cam retarding. Why not just tear the heads off, and install thick gaskets ?

Denny, thicker gaskets will screw up the squish and make the motor less octane tolerant.

Originally posted by lt1s10
by golly i will.

I was quoting you, Mike, and agreeing with you.

Originally posted by techinspector1
I was quoting you, Mike, and agreeing with you.

thats great tech, sometimes i dont know.

Originally posted by DennyW
Notice the laughing face ? I know what will happen, how ever he would drop a 1/2 point in compression. Why didn't he just buy the right crate motor to start with since it was a crate motor, and they have them in all sizes ?

I know you knew the consequences, but if I didn't spell it out, those reading it wouldn't learn from it. I totally agree with you that it would have been much easier to plan ahead and buy a crate motor that produced no more than 300 lbs./ft. of torque, but then we wouldn't have had the opportunity to have all this fun on this thread!!!!!

Thanks everybody for chiming in. I will try to slightly retard the timing a bit. I purchased this 330hp crate motor since it had the vortec heads which seems better the next model down. Changing the cam does seem like the ideal way to lower the torque or move the curve higher but I don't want to open up a new motor just yet. I got some Shorty headers with 1 5/8 primaries with super short collctors. So should I run 3" piping with 3" muffers. Would the lack of restriction reduce some torque.

Hopefully this exhaust setup would not be too loud since i'm trying to create a sleeper to scare my unsuspecting passengers, LOL!