stock 350 tpi with zz4 cam 85 iroc auto vs 95 trans am

**darkwingduck** · 04-03-2011, 01:16 PM

high i have a tpi 350 85 iroc and planning on rcing a stock 95 trans he has magnaflow exhaust i have zz4 cam with original drivetrain and rear gearing but i have a set of slicks that a friend of mine let me use since the iroc will smoke the tires for blocks. little info on race please the prize will be 4000 watt amp and rockfard forstgate p3s

**Whamhammer** · 04-04-2011, 11:11 AM

Originally Posted by darkwingduck

high i have a tpi 350 85 iroc and planning on rcing a stock 95 trans he has magnaflow exhaust i have zz4 cam with original drivetrain and rear gearing but i have a set of slicks that a friend of mine let me use since the iroc will smoke the tires for blocks. little info on race please the prize will be 4000 watt amp and rockfard forstgate p3s

Well, I can definately say that you should have an adavntage at lower rps with the longer runners, but unless youve updated the ignition system (especially the coil) and the intake/runner set up, you'll probably start lagging above 4,400 rpm. The LT-1s were more set up for higher rpm operations than the L-98 was was, it gave up (bottom end) torque of about 20 ft/lbs to the L-98 (345 vs 325), but got horsepwer and revability in exchange. But also looing at a run between a 25 year old car and a 15 year old car, vehicle condition also comes into play. Even though I love TPI engines, I'd flip a coin on the outcome.

**Firebirdjones** · 04-04-2011, 11:19 AM

Toss up if you ask me, I've owned both type of cars. My L98 actually ran better than my 97 LT1 6-speed.

I ran my 88 Iroc 350 tpi and 700R4,,,with an adjustable fuel pressure regulator set at 48 psi, shorty headers, and an edelbrock catback. Still had the stock 2.77 gears. Went 13.89 at 100 mph in that car easily,,with slight tire spin.

My wifes 97 Z 6-speed was a bone stocker and the best it would go is 14.20's at about 100-101 mph. Little more difficult to launch but the mph was nearly identical to my very lightly modded Iroc.

If you start modding the LT1,,,well then things change in a hurry.

**Firebirdjones** · 04-04-2011, 11:24 AM

Just wondering,,,you said you have an 85 350 tpi. The 350 wasn't available in the 3rd gens until 87. 85's were the beginning of the 305 tpi's.
I'm guessing someone has done a swap,,,is it still stock??

**darkwingduck** · 04-04-2011, 12:28 PM

yes tpi came out of 90 pickup but still stock

**Firebirdjones** · 04-04-2011, 12:45 PM

A pickup??? So do you mean this engine is a throttle body injection and not a tuned port injection??

**Whamhammer** · 04-19-2011, 02:54 PM

If you took the stock 90 TBI engine and bolted it up to the 1985 305 TPI setup, youre at a real disadvantage to that. The 350 TBI' sin 90 werent as powerfull as the 305 TPI engines. You'll have some real work to do.

**92z28camarokid** · 04-21-2011, 05:56 AM

Little for info would help us determine better. I was playing with my neighbors 94-95 Z28 manual one day and he took off on me on a straight away but I was slowly gainin on him. If we would have went side by side and actually honked I might have been able to pull him. And that was with my stock 350TPI L98

**Firebirdjones** · 04-21-2011, 07:39 AM

Originally Posted by 92z28camarokid

Little for info would help us determine better. I was playing with my neighbors 94-95 Z28 manual one day and he took off on me on a straight away but I was slowly gainin on him. If we would have went side by side and actually honked I might have been able to pull him. And that was with my stock 350TPI L98

Ya, my wifes 97 Z28 6-speed would MPH slightly better at the track than my L98 Iroc, but the problem was that the Iroc would get so far out front there wasn't enough time in the quarter to real it in with my wifes 97 Z.
My Iroc was actually a little quicker,,,but like I said, I had shorty headers on it, and an adjustable fuel pressure regulator. My wifes Z was a bone stocker.