Is swapping to TPI really worth it? Ignoring the looks factor and the fact that TPI motors made more HP than TBI stock, is it really worth it?

I have a 350 block waiting my decision, do I stay with TBI, or do I go TPI? If I stay TBI the engine will be built a lot like a '70-'71 vette engine Im told, same block and heads etc. I dunno if thats good/bad, havent had time to discuss properly with the shop.
If I go TPI, Ill probably go with the S&D intake ontop of the vortec heads (just saw it in the mag), unless someone knows of a better set of heads for the same sorta price.

What does everyone recommend?

Oh, about the stock motor thing, I was going to ignore it because I never did find out if it was the TPI that made the HP diff, or the different cam and heads and stuff used. Has anyone actually put a TBI and TPI on similar engines and tested like that??

 

I wouldn't swap to a stock TPI setup. Is the LT1 intake and some heads a possibility for you? That would be about the same price as a used TPI and the engine would have so much more power potential. Maybe the Vortec heads can be used w/ an LT4 intake? I don't know.

 

What do LT1 heads and intake run for?? I dont know a whole lot about TPI so I dont really know all my options.

Would that get me over 350hp or so? One of the buildups with the vortec's put out 350 odd hp so I was assuming that was pretty good. Is it for TPI?

 

You don't want LT1 heads, the LT1 intake can be modded to fit reg SBC heads. I'd just get some other heads like Trick Flow or AFR or whatever your budget allows, but not the Vortecs. The Vortecs need the special S-D TPI intake manifold to work. Do a search for the LT1 intake swap and you will find plenty of info. I think it can be done for $400, which is cheaper than the S-D TPI manifold you will need for the Vortecs. With the right cam, you will make WELL over 350 HP. I will suggest the LT4 HOT cam if this is a daily driver. This should make a little over 400 HP with good heads.

But, this is YOUR car, so if you want the Vortecs and S-D TPI intake, that is your call. I'm just letting you know for about the same price, you can get way more power and still have good streetability. Also keep in mind the LT1 intake will rev higher, so to optimize it, you'll need 3.73 or so gears and a higher stall. But most people get a TQ converter with TPI anyway and gears are only like $185. And if you have 2.77 or oher numerically low gears like me, you should get different gears anyway too.

 

Ok, done a little searching.

The LT1 intake isnt emissions legal is it. I gotta keep the car emissions legal. I dont know much bout the EGR, cant it be mounted somewheres else?

Do I have any other options as far as the intake etc?

Oh, and how much those AFR heads put you back?

 

I don't know the details of the LT1 swap. I have a SuperRam, which can be emissions legal, mine has no egr though b/c I didn't want it. I assume the LT1 would be emissions legal since it came from the factory. Maybe someone who has done the swap can chime in?

The AFR 190 heads are about $1500, but IMHO worth every penny. Heads are crucial to making power. But if your budget does not allow for them, get the best heads you can.

As far as other intake options, for EFI you have the stock style long tube TPI, SuperRam, Holley Stealth Ram, and LT1/MiniRam. The MiniRam is like the LT1 intake and I KNOW the Miniram is not emissions legal. Each intake shines at different rpm ranges and therefore each requires a different cam to optimize. Sticking to a tight budget though, I would keep searching and asking about the LT1 swap. It is the easiest on the wallet and has the most HP potential, but you have to rev the engine to get the power.

 

I see no way to make the LT intake swap emissions legal. For distributor clearance you have to cut part of the intake where the EGR bolts down, and running some sort of remote EGR valve probably isn't a good idea.

 

Yeah the LT1 intake isnt emmisions lega, neither is the HSR so your gonna have to go TPI or Superam .
As far as the swap goes I've heard its a real PITA especially if you have so so mechanical skills but youll like it better than TBI. If anything dont put TBI on that 350 go carb.

 

this is really the better way to go for the money spent, this style intake (holley makes this) can be used to provide much better flow than the tpi system, accel part #74882 is a 90 deg adapter that allows the intake to use the standard TPI throttle body holley also makes the fuel rails, the standard engine control unit(ecu), wireing,sensors, and tpi injectors and sensors can still be used that way and the intake flows enough air to make about 450-470hp (way better than the stock TPI system)

 

Grumpyvette, if he has to remain smog legal that intake manifold wont cut it.

My father converted his 92 RS from TBI to TPI, keeping the same 305 engine, and gained 17 HP and 70 TQ at the rear wheels. So yes, converting to TPI is definitely worth it, if you want a street car. He's now building up a 350 with the Vortec heads and Scoggin Dickey intake manifold, with a ZZ4 cam.

 

nevermind, lol..

 

While I'm still not too educated about the Lt1 & aftermaket intakes. I just did this swap on my Monte SS. While I'm sure the TBI is better than the carbed setup I took off. I can tell you that the TPI swap made a HUGE difference in my car, and I was able to keep all the emissions(needed in NY). I was well worth it.:lala:

 

I just swapped carb to TPI. Trust me, you don't have enough money. It doesn't matter who you are or what you do, you don't have enough.

 

TPI GUY hit the nail on the head , couldn't have said it any better myself.

 

convince yourself, drive one! feel it in the seat of your pants!

 

<b>I just swapped carb to TPI. Trust me, you don't have enough money. It doesn't matter who you are or what you do, you don't have enough.</b>

Man, Im going to kick you! Just when I felt really good about the whole CARB to TPI swap, you go and say something like that!

 

Why so much money to swap to TPI? I've done a few conversions on car that couldn't be had with TPI from the factory at all, and it wasn't that expensive.

The BIGGEST mistake I see people make is trying to save a $ here and there and piece a system together and they end up nickel and diming themselves into the poor house.

Hands down, the CHEAPEST and easiest way to swap to TPI is to find a donor car. I see RUNNING TPI cars go for anywhere from $300-1200 ALL The time. Yank the TPI, use the harness.....take pictures of the installed TPI before you start. All the "little" things that you'd have to run back and forth to find will be right there for the taking, and after you're done, part the rest of the car out to recoup most of your original investment.

Or just make sure you get EVERYTHING when you pick up a system. Look for a 305 TPI complete donor car, it's the same stuff as the 350 except for the injectors and PROM.

Use a GM HARNESS, because NO ONE makes a bolt in, TPI harness that keeps all the emissions and sensors working correctly without spending BIG $$$$.......


I helped convert a '83 Camaro to TPI awhile back. He bought a BEAT UP '87 TA for $750 in the local classifieds. It had a lower end knock, but it ran. It was a literal BOLT OUT / BOLT IN job.

After all was said and done, the swap MADE HIM a couple of bucks. He parted out what was left of the TA, and it covered the price and then some.

HTH

 

Your talking about just swapping over to Standard TPI. I could do that too for under $500 right now...

A stock TPI setup will simply NOT work on my car... For one the intake will not match my 76'block, but thats no biggy..

the biggy is a stock tpi setup is for idle-4500~ rpms. I have an engine that doesnt even make usable power until about 3500 Rpms! I would definetelly need to go stealthram or similar to get the kind of flow I need for my engine, or do a cam change (hmm...) But I would rather keep my power band...

And stealth ram is big $$$ especially if I want the 950 Holley ecu with it! Not to mention the laptop I gota buy... Sheesh.. Im thinking about it though..

I can go stealth ram or blower... which Do i choose? gas mileage or power? Hmmm...

 

King there is no reason not to use the SR w/ the 730 ECM.

As far as the cost of swapping TPI, CT is exactly right. Finding a Runner tpi Donor would most likely be the cheapest way.

However, Most of us don't hve the uxury of letting a parts car sit in the driveway for months whie we get it all sorted out, and depending on your area the avaliability of TPI donor cars is limited.

You sure as hell can't get them around here.

Your next best bet woud be to grab a complete setup off ebay.

I only chose to peice together my setup, Because I didn't want stock parts.

 

Just make sure everything is interchangable, like from the same year of vehicle. I got all my tuned port stuff off of the same car (89' IROC) and alot of the suff on the harness was different. Such as a manual tranny to a 5 spd , climate controls were different , harness to the cooling fan was different, single fan vs. duals. etc..... had to get wiring diagrams and rewire everything , unless you want to splice the stuff but that's horrid looking to do.

 

<b>King there is no reason not to use the SR w/ the 730 ECM.
</b>
What is a 730 ECM and what cars have it?

<b>Your next best bet woud be to grab a complete setup off ebay.
</b>
Our THirdgen.org Sponser "third gen resource" Has them for $450 complete minus fuel pump (if they are in stock) I would buy it from them probably... if i went this route.

I think the cost of a supercharger setup is way more than I Want to spend on my $2.04 car... And I built the engine low compression specifically for boost... I think I am going to just put a blower back on it and maybe use Holleys Dfi Projection (throttle Body) to get some of the benefits of EFI. The thought of a Stealth Ram setup is nice, But the part where the boost comes in scares me. alot. Thanks for the replys guys, I appreciate it, but I think I've finally made up my mind. Now the question is what comes first... Blower or Dfi? hmm...

 

The tpi makes tons of low and midrange torque. I did the swap on a stock heads, cam, and exhaust tbi 305.