I have an 89 T/A with an '87 350tpi from a GTA. My car's an auto and I'm not sure what gears it has. It originaly came with a 305 and it has limited slip. I have cold air with a K&N, Random Tech exaust, gutted cat, all free mods. My plan is to one day be able to run with an LT1. I'm planning on a throttle body, ignition, AFPR, and probably plenum, runners, and base. I will probably need headers too, maybe a cam. Will I make it with these mods? What else would I need?

 

My 305 runs with LT1s with ported aluminum L98 heads, LT4 cam, 1.6 roller rockers, edelbrock headers, high flow cat, borla exhaust, fog light ram air, afpr, full msd ignition, edelbrock intake, stock runners, ported plenum, stock TB and MAF, 700r4 with a shift kit, stock torque converter, gears, no weight reduction. Probably some stuff Im forgetting, but basically with heads, ported intake, exhaust, and a cam--you will blow any stock LT1 away. If you want one piece of advice from me, that would be to get new heads. I threw the heads, headers, intake, and cam on in a week, and you would not believe the difference. Thats only a couple weeks to go from a 15 to a 13 second car, and it should be much easier for you.

P.S. Don't leave an MSD box in your car, it just screams "break in and steal me!"

 

It's not as hard to make it to LT1 territory as most people think. The important thing is, doing it inteligently. Take your mod list for example. The TB is a basically worthless mod until you are well into LS1 territory. Put the $$$ towards an immediate need. By ignition i assume you meant an MSD box or similar. Again, this is a completely useless mod unless you have a high compression very high output motor, or are running a serious power adder. Put the $$$ towards something better.

Basically, first you'll want to verify gears. If it was a 305 A4 in a previous life it prolly has 2.73s. Check the RPO codes in the glovebox for the Gxx codes and look 'em up from the main page of TGO. GU2 is 2.73s, G80 is posi. G92 is performace axle, which in an A4 car means 3.23s. There will be a GUx code for 3.23s as well, but i don't know 'em all offhand.
Anyhow, if you have 2.73s they need to go. 3.42s are about as perfect as you get for a LTR TPI set-up. 3.23s won't kill you but you'd prolly want t torque converter at some point.

Your biggest restrictions to making power are the stock TPI base, heads and runners. The stock cam also leaves much to be desired. Porting the plenum is a good idea just cuz it's cheap/free. Headers are basically a must unless you always want to be a couple steps too slow and use the stock exhaust manifolds as an excuse. An AFPR is a decent tuning tool, especially for a basic MAF combo. The stock torque converter also is too tight for real performance use. I know i'm throwing abunch of stuff out here. You doj't have to do all this to hang with 4th gens, i'm just trying to illustrate the main things you should look at. At this point my best advice is to search and browse these boards so you can understand exactly why all these parts are a bottleneck, and then figure out where you want to go, and how you're going to get there. But the TB and an ignition would only leave you dissapointed if you werent already into the heads and cam.

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Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.7 @ 93.6
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

 

don't forget a L98 beats LT1 in torque (until 98+). Its past the intersection is where you u need to worry.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

[This message has been edited by breathment (edited November 05, 2001).]

 

I remember flat out passing an LT-1 TWICE (same car on the same stretch of road) even with him having me on the launch. this was what I had at the time:

L98, home made cold air, pulleys (crank and alt), airfoil, ported plenum, Edlebrock TES,
Flowmaster, no cats, MSD wires/6AL/blaster coil, all the free mods, LCAs, urethane bushings, 3.23 gears, and a 5 speed tranny.

I didn't know the guy, so I don't know what he did to his car. BUT, I knew that he had a cat-back exhaust because it didn't look like the stock exhaust.

 

1st Go to a track and find out approximately how fast your car is. High 13s is game for any LT1 stock or with few basic bolt ons(exhaust(headers)/tuning/CAI etc.) LT1s generally/typically run from 13.7-14.4 at 97-102mph stock or lightly modded(see above). LS1s generally run 13.5-12.9 at 105-109mph stock or with little mods. TPI cars seem to vary so much that it's not worth it to assume your car's performance, but I'll say it anyways, stock 305 TPI auto ~mid 15s stock, Stock 5 speed 305 TPI mid-low 15s(maybe some high 14s too), and L98s anywhere from low 14s to mid 15s.

In general I'd say 3rd gens gain the most from the simple mods(exhaust(headers)/chip/CAI) than the newer cars b/c they had/have better technology in them to begin with. Get your car to run high 13s following pretty much exactly what Ed Maher says and you'll hang with "most" LT1s.

I'm not a big fan of buying expensive LTR(longtuberunner) pieces b/c I feel they are limiting power if you want to get well into the 12s or even into the 12s at all someday and the money could be spent on more important pieces first mainly heads/cam, after exhaust/headers and ColdAirInduction (obvious first mods to any car)

And I agree ignition boxes and throttle bodies are waste of money until real low 13s and high 12s are in your sights.

For your specific application I strongly recommend headers as your next mod. And then some sort of chip from Ed Wright or preferably a good friend that can burn chips for you. I'm very happy with my $80 SLP chip though.

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14.62@96mph headers, muffler, chip, ghetto stuff, duct tape
89 GTA 305 TPI 5 speed 3.42 gears

 

thanks a lot guys, I can always count on good replies when i'm on a thirdgen.com message board.