3.1 Gen2 on a dirt track..

[DirtRacer]

I have recently slightly modified a 3.1 to race on a half mile dirt track circuit.
Running in a manual 92 Cav.

Put a new cam (420-443 lift cam)new lifters, timing chain.Also put 1.6 roller rocker arm a 1.6 ratio from comp cams. Also port match all the runners from the UIM, to LIM ,heads and exhaust manifold. Put 3400 exhaust manifolds and 2.5 inch pipe. Also put aluminium damper pulley and a fidanza aluminium flywheel. Done a little polishing in the TB. Also put back the stock chip in the ECM since everybody is telling me that my JET and Hyperchip is worth nothing.

The car is pulling harder from the corner but still have the same endpoint at 5300rpm. What have i done wrong??? I knew that the gen2 stuff was flow limited but all the porting done bring nothing to the top end!!

thanks..

[CNCguy]

The 3.1 is limited by the top end but it seems that you would have gained a little more on the top end from your mods. Have you replaced your valve springs?

You might check with Ben to see what he has to offer in chips. His are much better than stock, Jet or Hyper. Investing in the equipment to do some wideband tuning could be worthwhile. Logging during hot laps or test and tune could give you some valuable information.

We are getting ready to test bore some 3.1L TBs to see where the limit is. Bored TBs will be available in the near future.

[DirtRacer]

Block and heads are stock. Would new springs bring me some RPM.??

Also, what kind of spring is recommended without any modifications??

Thanks.

[sharkey]

a 3.1l doesnt have top end. even with the porting and increased flow, its not enough to feed the motor.

are top end swaps legal??? if you can, id throw a 3400 top end on it, that would realy wake it up for high rpm.

[XLR8ING]

5500 rpm is the max (still making power) I've hit with a stock 3.1MPFI intake manifold, even on highly ported heads, bigger cam and better springs.
I could take it to 6000 rpm, but with no gains when running 1/4 mile.
Dirt track may be different though.
Like Sharkey said, go with the 3400 top end if possible.

[pontiac3100]

6200rpm and i could still feel her pull.
on my accord once it reached 5200 (reline was like at 5500-6000rpms) you could feel her power drop.

the 3100 i don't feel.