Hey, anybody experimented TBI mods like performer manifold, ultimate tbi mods, chipp burning, headers, highflow cat and cat back? Everithing keeping it emission legal!!!

I have a 91trans-am Lo3 and the car looks nice and fast but does not give me what I expect from a 5L engine. Is TPI conversion the way to go?

 

I have, what do you want to know about it?

I say TPI is NOT the way to go.

 

I purchased tbi prformer manifold, extremefi 46mm tbi, walbro255, still loocking for headers and highflow cat + cat back. And asked miself If I really know what Im doing and admitt, not at all.
How mutch hp? Are you happy with it? Would you do it again? Any advise?
Than you.

 

I think you will hit close to 200 HP, IF you tune your ECMs Chip.

https://www.thirdgen.org/forums/tbi/...-tbi-mods.html

 

Nice your post. How did I miss it!
200hp would be with the complete exaust right?

 

Are you going to be reusing the L03 heads?? I had a L03 at one time also. I wanted to swap to TPI on my L03. Was told the heads are a little different on TPI 305's, so you might not get all the power that an original TPI 305 might have. I would recommend staying with the injection system that came with your car. Chip tuning will still be a large factor in any fuel injected Computer Controlled system. Changing that harness was the most difficult part of the whole engine swap, in my opinion. The old rule still stands though...Cubic Inches are the cheapest horsepower gain.

 

I am still learning things myself, but here is my feedback. You are doing good so far. If you are not trying to be the fastest car on the streets, then the parts you have bought so far will give you a fun ride. The Walbro fuel pump is a good supporting mod if you want to really build your 305 or swap a 350 engine later. Definately pick up headers, and a bigger Y-pipe and catback with an aftermarket muffler. Don't forget to pick up the open element air cleaner, or at least the dual snorkel air cleaner that comes stock on the L69 equipped F-bodies.

After of all that, tune your computer and see where you are at. If you are satisfied, then good. If not, then there are other budget parts you can add, such as the stock cam from an LT1 or L98 engine, and the stock heads from the 305 TPI engine.

Take a look at my engine mod list, my car is a completely new monster compared to stock. I have not dyno'd it yet, but I know I am definately over 200whp, which is enough to satisfy me (for now). My car did not unleash its true HP until I had the computer tuned after the mods, which is one of the biggest factors in making power on our cars, and having them run right. For more info about tuning the stock computer, you can check out the DIY PROM section here on the boards: https://www.thirdgen.org/forums/diy-prom/

So to answer your question, No, I don't think you should swap to TPI, at least not yet. Wait it out and see if you become happy with your TBI + mods.

 

Thanks for positive imput. Ill try and go with the suggested upgradings.

 

just don't get too carried away with your mods to TBI and then decide to change later- Swapping to a kick *** TPI is not cheap!

 

Good point, wen you convert a tbi to a good tpi you need $$$$ to get started. Upgrading a tbi is possible by spending $$$ on a larger thime scale.

 

I can't stress enough...........no replacement for displacement

 

Same here. I made 423 FWHP with a 305 TBI, but I bet it would have been 500 FWHP with a 350.

 

Damn!?!? Really? Boy I wish I would've none that before I ditched my L03! I went 350 TPI, can't say I regret it though. Love that Polished TPI.

 

I have gone sequential TPI as well. This is the test fit of the TPI intake on my 1983 G20 as I was pulling the Darts off my 350 TBI. This same intake setup went on a 305 in a 1994 G10 Van. The 305 TPI/4L60E combo was then run by a late model Vortec Express PCM and harness. Great running combo. In fact I have never seen another TPI Van.

 

You must be eating tbi's for breakfast!
GM fastburn heads, World product heads or 305 TPI cilinder heads? For a LO3 with the erlier mentioned mods.

 

None of the above. The 2004 up ZZ4 Aluminum castings flow very well, have 58cc chambers stock, support like .525" lift out of the box, and are aluminum. A little bowl work and a back-cut on the valves will typically make them out-flow stock Vortec heads.

 

Do you know a store where I can get them ready to bolt on?