I'm SURE this has be covered considering this forum has been around since i was in high school, but i cant find it.

My friend Ken (he is on here somewhere) bought an 89 GTA with a TPI 350 swapped in it.,

On a 350 TPI car, after intake, headers, exhaust what is the general upgrade path for the TPI cars? Is ditching the TPI in general a common thing? Pump, injectors? What are the common bolt-ons before cam/heads/power-adders?
We dont want to jump into an LS swap or some crazy ****. We would far prefer a series of weekend projects and keeping it drive able.
Last time i did any real work on third gen's they had carburetors.. If this has been covered 1000 times before (like im sire it has) if somone could point me ot a thread and delete this one that would be great.

Thanks guys.

 

Higher stall torque converter and numerically higher rear end gears.

 

Thank you sir.

Did they all come with the same rear gear? If so, what was it, and whats the common jump for a "street car" 3.73?

 

It depends what rear you have, but yes, in the neighborhood of 3.73 will completely change the feel of your car.
And no, they didn't all come with the same ratio.

 

I think you'd be better served by knowing what you want to end up with and building towards that goal. TPI is a very long runner design so if you're keeping that style, it's going to influence your other build decisions significantly. Once you start getting into heads and bigger cams, you're also going to need a tune or alternative engine management.

 

Thank you Komet, this is the stuff I'm looking for!

The goal will be somewhere in the 325-350hp range. With maybe a little shot of nitrus. From what I read anything starting to head to 400hp and up doesn't make much sense on this motor, is the right?

What are the alternative options to the TPI intake? If we go with another intake system how involved does that get as far as electronics?

Are there any benefits to sealing back to a carb or even one of those Holly FI systems that look like a carb?

We live in the middle of nowhere, finding a tuner that can work with this thing is probably going to be a long shot....

 

Welcome aboard HawkForum6
If higher performance is the goal whether it's straight line performance or road course/AX performance, sub frame connectors should be top of the list of up grades
https://www.thirdgen.org/forums/susp...on-thread.html

 

https://www.thirdgen.org/forums/alte...nversions.html

 

You're probably looking at changing the induction system to hit those numbers. TPI was designed to build maximum torque as fast as possible, and as efficiently as possible on a 5.0l engine. As a tradeoff, it loses the ability to flow a lot of air above 5500rpm (which is where the big hp numbers live). Having a bigger engine futher exacerbates the situation to some extent. You can enlarge the runners, port everything, etc but you'll never really get away from the characteristics of TPI due to the runner length.
Carburetors, HSR, FIRST TPI system, Edelbrock has a setup, Holley has their own multiport setup, sniper efi are all commonly available today. You should consider all except the carbs to be a full custom electronic setup. You might be able to use the stock ecu but not with the stock tune.
An induction system with shorter runners (and/or significantly larger runners such as the FIRST) is going to open up the airflow at higher rpm, which is going to allow you to run a more aggressive cam profile, which will ultimately allow you to make more hp. On the downside, you'll lose the torque production on the low end so it just depends on where you want to make your power and why. TPI is a cool setup but it comes from the factory sorta maxed out on making power where a stock engine on the street is actually spending most of it's time, and it sacrifices the top end to do it.

IMO, when you start designing a really optimal, modern sbc build you end up coming to the conclusion that the ls is actually that thing and you'll spend the same amount of money and engineering effort either way, it'll just be on different things.

 

Thank you Komet, I really appreciate all this info.

I'm sure you are right about the LS in the long run. It's just a huge project and an expensive project. We where really hoping to have a series of smaller projects so we can keep the car on the road as we do upgrades.

The other aspect of that is we are working out of the shop we have at work. We have a bay with a lift and most of what we would need for tools to do that swap. But I can't let the car sit here for weeks. I would imagine doing an LS in a weekend is not a realistic thing especially if you have never done it before.

Maybe we focus on just getting this running as best it can be and getting it cleaned up. Focus our energy on some of the cosmetic and chassis stuff and just plan for an ls in the future. .

I was hoping for a reasonablly cheap and easy path over that 300hp mark to kinda be our GTA v1.0 to let him enjoy the car and feel some power. But sounds like that's not an easy goal to reach.

Out of curiosity, are tpi to carb swaps frowned upon for the most part? And how hard would it be and how well would it handle it to feed her a little nitrous as is?