So I am thinking of overhaulin' the drive train in the 1990 GTA. The engine is a L98, so I am looking at a complete rebuild with performance in mind. I want to try and keep the stock look, bored out 30 over with new heads, March pulley system, ignition system, intake, cam and lifters, hi volume oil pump etc. I don't want to go to wild, and I don't want to be alittle bit better than stock either. Somewhere in the middle, hoping for 300-340 hp at the wheel.
I will be redoing the stock exhaust with headers, hi-flo cats and a 3" catback.
I want the transmission rebuilt as well with new tq convertor, corvette servo and a Trans Go shift kit.
The rearend I want to replace my 3.23's with 3.42's and upgrade the ol' 10 bolt to handle the extra torque.
So, anyone have any ideas what I need to acheive this goal...I am looking for some ideas. I was already thinking of a single turbo or possibley a supercharger, but it seems to be alot of modifing of the engine bay to go that route
I also want to keep the car emission legal as well.
Once I have a better idea as to what I want, I will contact an engine builder with the info
Also, the car is numbers matching and original, so I have no plans on swapping in an LS motor...

First TPI, ported 113 heads, cam of some sort. You could also go with siamesed runners and ported aftermarket lower intake. It would probably be easier with a different style intake. Or just get a D1sc with a 12lb pully. They're fairly bolt in.

I hadn't thought about a ProCharger set up...pretty pricey, but they are Canadian. I guess I would have to look at the fact that I still want the engine rebuilt, so do I rebuild with hi-performance in mind, or do I build with the use of a ProCharger for the HP I am looking for? If I had the serious coin, I would build with hi-performance parts and a ProCharger...

Im not big on tpi tech but i do know its very hard to find someone to tune and burn proms. That would be the biggest obstacle if you plan to add heads/cam etc and mess with the tune.

I would think a refreshed motor with headers/exhaust and the rebuilt trans with a stall and a set of 3.42 gears should make big difference!

I plan on using a stand alone when I need a custom tune. AEM has one that's self learning. The 24x is also an option. Would be able to get by with an FMU and BTM with a refresh and procharger.

To get 300+ na out of a TPI is going to cost you some bucks and take a lot of work and sadly it probably wont behave worth a damn.

If your serious and I mean SERIOUS about making this thing work you need to upgrade the management system. You could do an LS ECM swap on the cheap if you can sort out how to do it, contact eficonnection for advice and cost estimates. ECM is fifty bucks and wire is free if you salvage, the rest you should be able to cobble together from yard parts at the u pull. If you want to go easy and full tilt? Buy Holley ECM and go nuts with ANY mods you want, it will work mint.

Problem with TPI is the computers are old and dumb, so once you mod, your tuning non stop forever and its just wrecks the behavior and its no fun to drive the car anymore. Who drives a heavily modded TPI? Does anyone? I seriously do not personally know one single person who does this now, we all tried, poured tons of dough and time into them, and we all ended up of the same mind set. Modded TPI = money on the fire. Leave it stock'ish and enjoy it or go alllllllll the way is unfortunately the only two sensible choices available. The downside to option two and modding alll the way is for 20K your still going to get your ass handed to you by every LS built for 5K so its your money, spend it how you like.

I dont think you could get a stock intake over 300 whp na and if you did? its gonna cost you... pricey pricey. So that means an intake swap and the only one we made any power with was the Super Ram which looks like meh, and sure it performed decent with consistent 12's, but that was after trying a few different bases and runner set ups, none of which hit 300 whp I think 268whp was the higest we ever dynoed that thing at. Edlebrock E tec heads, super ram, 1 3/4" headers, cam, built 355 short, you name it, we had it, and it was still slow considering my BBC Nova was 1/2 the cost and 3 times as fast.


I can totally understand wanting to stay stock looking, nothing really looks cooler than a TPI set up, too bad they dont perform worth a damn. Now if you want the easy non wreck your car route to making power? Peel off all the TPI stuff and go carb, you can always put it back to stock that way without issue and you can hit that number easy. Just dont open the hood at shows and no one will be the wiser if your concerned about stock looks etc. An LS you can hear easy, but a carb sbc or TPI sound pretty much the same.

Performer RPM intake, Decent 750 carb, 1 3/4" long tubes, good single 3" or 3.5" exh, 224 range cam, AFR or Edelbrock heads should get you over 300 whp. 250ish whp on stock heads is my guess.

I saw a P1SC on a TPI on the dyno and it didnt make 300 whp either btw... Just saying boost isnt the sure fire answer either without a good intake and a management system that works, boosting a TPI is also a giant waste of time and money. No matter how you slice it the TPI intake and the stock ECM are BOTH achilles heals.

I have hit over 300 hp on a TPI, many times actually, the hard part he is going to face, is his desire to stay LTR. The FIRST was a good suggestion above, but really it will come down to his heads and cam combo after that, CI's will help.

TBH a sweet set of AFR heads is around $1600us, and of course with the rest matching they will do it, BUT I can get a used LQ9 for around $900 and carb it or, around $1500 complete with ECM, and it hits your 300rwhp already in stock form. Soooo... that means it is totally upto Kevin/Laurie on what direction they really want to go, cost effective the LSx family wins. Staying with the stock block, its doable but will cost more, staying with a LTR style, still doable but adds even more to the cost.

What is wrong with the stock engine? Tired? Does it really need a rebuild? If not, stuff a rear mount turbo on it with an FMU and some new/slightly bigger injectors and call it a day.

If it needs a rebuild, go 383, 350's are a waist of $ now IMO, but then who am I, lol

Good luck with your build, regardless of what direction you wish to go

PS. here is a build to read up on
http://www.gmhightechperformance.com/te ... t_top_gun/

This thread is informative but at the same time very conflicting....lol....I have my own build to plan for and just like Kevs87TA, my goal is also 300-350hp at the wheel.

@Kevs87TA - Hope you don't mind me chiming in here as we need practically the same info?

Firstly, I've been watching a lot of videos and reading up on a lot of builds. Is it more cost effective ($ spent for hp) to swap out the L98 for a truck engine/LS engine OR machine/reuse the parts and add bolt ons to build a 355 or 383? I assume that swapping would mean some sort of modifications to engine mounts and such?

One Powerblock video seemed to indicate buying a new shortblock and components from Summit worked out cheaper than getting a machine shop to do the work on an old block.

Initially I thought I would go with a 355 build but I'm getting differing opinions. The car needs to run pump and pass emissions.

Newb to V8's so bear with me on the questions.

In the end it alllllll comes down to ONE simple thing;

COST. How much are you willing to part with to build what you want?

Cheap, fast, durable. You can only pick two


Just try and remember this advice comes from years of mistakes and wasted cash chasing the same dreasm as y'all so im only offering up this info to help you avoid the same pitfalls. Some guys need to learn the hard way I guess which explains why theres 99/100 "build projects' that never leave build stage and live on jack stands. ( I've had more than enough of these failed projects to ever want another one )

Remember Im not selling anything here.... I'd love to see another 500 sub 12 second third gens out there representing properly, thats my only goal.

If anyone here gets a sub 12 second TPI car built thats as fun and easy to drive as what I mention? Id like to see it when your done because I want one too and want to know how to do it. Rear mount might do it, but on stock TPI ecm? It's not going to be easy....


Anyways my final note on this here it all comes down to the bucks. Sort out how much your willing to spend first, and decide from there. Money can only be spent once so spend it right and have fun!

Keep in mind that a 5.3L with a cam, headers, and proper tune will crest 300whp with ease. Around 2K will do the whole build plus tune costs if you cant do it yourself. 500-1000 pending how good a job you did building it. Trying to tune an engine that wasn't installed or set up properly is ten times harder ( read more than one trip to the tuner $$$ )

No problem , one thing you will learn,everyone will have different opinions. That is why I posted this topic. A lot of people have had experience doing exactly what we are hoping to achieve. It's up to you to decide how you want to proceed.
Anyhow, the reason I don't want to swap in a LS motor is that my GTA is a fairly rare car,only 1 of 105 that came with the L98 in 1990. That's just me though. I want the original look of my car, yet get better performance out of it. I do realize that tuning it may be too difficult, so, may just do what Vetty suggested. But, it doesn't hurt to hear what people have to say. Like Cam said, it all boils down to how much you want to spend.

@Kevs87TA - No Doubt. I expect there are hundreds of combos that will get us the results we're going after.

@cam - I'd pick Durable and Fast. I'm not necessarily looking for cheap...just don't want to waste money on mods that aren't going to do squat. With that in mind, I research months in advance to make sure I know every aspect of the build and what the results might be BEFORE I make my purchases.

Ideally, I'd like to learn from someone and build it myself. The part that always interests me in being part of a club is the DIY aspect. Especially if locals are willing to lend a hand, mod days in someone's garage, beers etc.

Whats a good machine shop in the GTA (Mississauga preferably) that can build a solid engine?

Kevin I know of quite a few guys who carefully remove the numbers parts, store em stock and clean, and build monsters in a fashion that doesn't wreck the originality of the car. I could swap my 87 back to stock in a few weekends, no one would know there was ever an LS in there. Heck every single dude with a points style ign who drives it does the HEI swap and keeps the old points stuff when its time to sell. This is so common place now that it doesnt even affect value anymore. Just something to consider. So long as you dont hack out wires and cut up the tin, it can always go back to stock if thats really important to you down the road but look at whats selling for what value? Stockers are not commanding big bucks, unless they are first gens or early 2nd gens stock doesnt increase value. it takes a nice built third gen to get dollars out of it. So you could just yank out the stock engine, trans, and harness and keep it. Cost? One weekend and ZERO dollars. Then start with whatever engine you want. SBC TPI based build? Go for it. LS swap? Go for it. Wont wreck the car, and certainly wont cost you anymore to do this and keep your stock stuff if you think this is whats going to make the car valuable one day, your covered. Remember to go carb you only need one power wire to the dizzy and supply fuel and she'll run. You'd have to be baked to mess the car up by doing that and if your going to stay SBC? Carb is the only way to fly imo. The cost of hi-perf sbc fuelly stuff just doesnt add up to me but again, your build, your dough, just be sure to enjoy it and dont get angry or hate the build when it doesnt work out as planned ( power goals are almost never met ) and it tends to cost twice as much as you figure by the time your done. This stuff is supposed to be fun and if being "different" is important to you? Just be mentally prepared to pay triple or more to achieve the same performance as the masses.


gamewiz83 whats your performance goals? Budget? You need to set goals and target them and then decide how you want to go about it. You want to learn? Start simple and go from there. For anyone contemplating an LS swap it does seem daunting from the outset, I get that, been there. But the trick to an LS swap is to get the PLATFORM swapped over and this is a LOT of work, and VERY little cost if your willing to use a 4.8 or 5.3 to start with and keep it stock at first and go at it in stages. Read and teach yourself what it takes. Start here

http://www.thirdgen.org/techboard/ltx-l ... d-gen.html

Then read here

https://sites.google.com/site/sloppywiki/

Theres lots of guys out there now with complete swaps done and on the road for around a grand or two. Stock engines mind you but still.... its doable if your frugal, shop smart, and have time to visit yards often etc. Dont have time and just want to buy parts? 5-10K should cover most NA LS swaps.


Once you have an LS friendly platform? Mods are so easy for more power, cheap too. Heck up to about 400whp can be had with mostly stock parts, cam, tune, and done. Just remember this no matter what rag or post you read there is a formula that is NEVER broken easily, or cheaply. When it comes to naturally aspirated builds 1.6hp per cubic inch is the limit. Its pretty easy to get close to 1.6 per, but after that? It starts to get mega pricey, and/or mega undriveable ( read that as race only car ) Boost? Far as Im concerned the words CHEAP and BOOST, simply dont go together at all. No such thing as cheap boosted builds, at least not any that hang together long, or run fast. On the LOW side of things expect 10-20K for a good boosted build but you can also expect 800+ whp if you listen to those who know what parts to use.

Let's put it this way. My goal is 300 - 350 hp at the wheels. Full suspension and exhaust upgrades.

Is it more cost effective and less time consuming to do a 350/355/383 build or an LS swap to meet these goals?

^ If you go with a carb, probably. But it will still be pretty close and as I said there are guys who have done it on the super low buck, with either set up. But that all depends on your skills, knowledge, and luck of finding deals.