Hello all,

I have a 1988 Pontiac Trans Am GTA with 115 000 original miles. I have the 5.0L LB9 Tuned Port Injection (TPI) engine, 4 speed automatic transmission (rebuild 10 000 miles ago to original specifications), 3.27 POSI and every options except leather interior.

I would like to do some modifications to it so I can match a stock 350 TPI car or even be a little better. If I could hit high 13 in the ¼ with the less money and troubles possible, I would stick with that for years to come and I would be very happy. Keep in mind this is my daily driver in the summer, and I live in Canada were it’s not as hot as in the USA…

Please list the mods in the order you would do them. I also would appreciate it if some of the experts here could give me the combo for an LB9 that would best suit my needs.

Thank you so much and see ya!

 

Id do lots of traction mods, gears, and a full exaust system. A good shift kit can also help shave time off by reducing the time it takes for the trans to shift.

Another thing id do (this will drive the tpi guys nuts) is to switch over to a carb manifold set up to accept fuel injectors. Id top it off with a junk tbi with no injector pod or some other fi throttle body. Put a carb hat on it and hook the maf up and the computer will be none the wiser. With this you can also run a better cam without having to worry about the tpi intake. Its good for midrange performance, but itll cripple the engine over 4000 rpms. It hurts engine performance when your out of the range that the intake runners resonate at.

Itll probably need tweaks to the prom to make it run right. More specifically, the injector constant if your going to be running larger injectors. Youll also probably have to change timing tables to match your new setup.

 

Have you gotten a time slip at the drags for your car yet?

New TPI friendly hi perf camshaft , ported stock heads(larger valves) , raise compression ratio,
higher rear gearing, high stall torque converter, Sticky rear tires, Nitrous oxide injection, ported intake manifold and plenum. fuel pump upgrade. prom tuning. Exhaust headers, high flow cat(s) hiflow 3" exhaust.

It will take a combination of overall improvments in engine airflow, gearing and traction to get you into the 13's.
You'll need about 280/300RWHP. By going to the track and getting a timeslip, you can calculate the RWHP you have now
and how much you'll need to add to get the performance you want from your car.

Turbocharging is another good possability.

www.ststurbo.com check this out

 

I didn't got the chance to go to the track yet.

Well, I'm not rich, what would be the best mods so I can at least be on par or a little better than a stock 350 TPI?

Thanks!

 

exhaust-headers back, stall converter, gears, and traction. also, look at the thread you made in the TPI section, i left a huge list of goodies there. check out the "Baddest n/a tpi 305" thread on the TPI board as well. it's got a bunch of good ideas. do it one step at a time and don't get discouraged if it takes a little while to accomplish these things. if you do it in steps, you can have a really fast car in like 2-3 years! look around for sales on used stuff too. you can get headers used for like $200. i just sold a set of coated hooker 2460's for like $150.

 

The cheapest Bang for the buck mod that will add significant acceleration improvement and beat those pesky 350's is Nitrous Oxide Injection.