No Top End

[john266]

Does anyone have any suggestions to gain any more top end power out of the 3.1.  Around 5000rpm to redline, the car seems to lose power, and is nothing more than noise.    I was considering gutting the cat (like I was talking about in a previous post) because I know that will help.  I already cut the stock muffler off and replaced it with a glasspack.  I know there is nothing wrong with the car, the motor runs like a top, I just want some more top end.

[wicked-irocz]

the 3.1 was not designed to see over 5000 rpm really.  The best thing to wake it up is a 3400 top end swap but once you go that far a 3400 is a better option dollar for dollar.

[Money pit Beretta]

http://www.domesticcrew.com/660/hybrid.html
Take a look at that. The only thing I could come up with other than that,was to have a chip burned to lower the shift points. I don't know why GM set it up to shift a 5200rpm, as you said there is nothing up there. The only way to have power at that RPM is to get a bigger cam, but you will lose MPG. Guess you could look at this also, but it will not help much because you will need ported heads to match http://wot-tech.com/shop....28.html
A 3400 swap will give better power to weight(I may do this),but I'm not sure what your MPG will be. Could be the same because of the 3400's bigger bore.

[1988GTU]

To rev higher in a 3.1/2.8 you need more air and better valve springs.  How you get it is up to you.

You can do boost, juice, 3x00 swap, or heavy port work.  
I would shoot for boost or a swap (or both if you have deep pockets) .

[leadfoot93]

i supercharged mine through the stock manifolds because the manifold is so flat.  there's pictures here but it has  the same rpm problem.  those heads and intake are JUNK.  they're super long very narrow tubes designed for low end torque and driveability.  when they redisigned it with the new 3x00 heads and intakes the fixed this to give more top end power.  If you want a high rpm powerful race motor you need to get the newer short fat intake of the 3x00. the 3.1 is only good for torque and low mid range like a diesel even if you put in a high lift cam it won't give you high rpm's because the whole intake and head is designed for low rpm's. you might see more mid range power but the runners max out first so you need the pressure of boostin order to make more power.

[leadfoot93]

ok i just thought of this and it would be interesting to try.  once you get the top plenum off the motor go to the junkyard and scavenge up 5 more throttle bodies.  get the blades machined smaller like 1.25 inch diameter and have them press in aluminum bushings into all the throllebodies(with holes for the idle air solenoid passages)then machine the two rows of runners on the upper plenum off and weld them to the bottom of the throtlle bore spacers.  splice all the idle air wires together cross tee all the vaccuum lines to equalize chamber pressures link together all the throttles to the original one and use it's throttle position sensor.  no wierd tunning a llitle fab work and a small amount of cash latter and you will have taken almost 6 inches off each runner will with a 6 ram intake.  You should be seeing higher rpms after that.

[leadfoot93]

just an update on my last seemingly crazy post some guy with a 2.8 fiero actually did that and put a vid of it on streetfire.net i'll try to dig up the link.