Jabberwocky

Ok, I have 2 problems, which are autocross related.

First of all, I've notice my LT1 engine tends to get a surge in power once it hits 3000 rpms. It is very unsettling to have you foot all the way down whilst getting ready for the next corner, then suddenly have the car lurch forward. The engine sound changes noticably and the acceleration picks up. At first I thought it was my clutch slipping but the car clear accelerates faster. Does anyone have any experience with this on a stock LT1? I don't know if I somehow lost some lowend torque or gained some high end but I would prefer my car to accelerate smoother.

The second problem I have is with my alignment and tires. The car has 275 tires and a slight toe out. It's twitchy as hell on the highway. Is there a way to counteract this besides getting the car aligned to a neutral toe or less. Everytime I go over bumpy roads the car starts twitching left and right.

LPEdave

Do you have a stock throttle body? I noticed a fair variety in the profile or cam on the throttle cable, and that has a big effect as you say. My Accell/LPE TB for example was very non-linear, and harder to modulate somewhere between zero and WOT. I had the same issue at the Autocross as you're describing.

Your best bet on the twichiness is an alignment, but that's probably counter to what you've set up for autocross. Fiddling with tire pressures might also help a bit.

Dave

JimMueller

I don't know about the surge...

What are your alignment specs now? I run -1.5 camber, 3/32 total toe-out, and 4.5 caster. Perhaps I'm just used to it on the street.

You could try adding a bit more caster to help the car go straight, but too much might tax your power steering. I had mine at 5.5 for abit, and it was groaning everywhere even though the reservoir was full. Dropped it back to 4.5 and it's content again

Jabberwocky

I think I solved my surge problem. I had previously plugged up the resonator tube on the intake elbow. I think doing so reduces the amount of pre filtered air available, thus hurting throttle response. The scavenging effect is probably increase at high rpms and helps power, but the low end is hurt because the amount of dead air is reduced, kinda like reducing the size of the plenum. This is just my theory, but putting the resonator back does seem to help smooth out the accleration a bit. The engine still seems pull a bit harder once it hits 3000rpms.

I'm running relatively little caster, I think around 3.5 degrees. I use to have it at 4.5 but some reason the shop couldn't get more than 3.5 when I last got it aligned.