Hey guys. This is not really a thirdgen related question, but I've received such good help here with my RS that I figured there's no better place to ask this.
Here's what I'm doing, I will try to keep this as short as possible. I have a 94 S10 pickup, 4.3 TBI. It's getting a V8... no big deal, already put a carbed 350 in my 88 S10. The actual swap is no problem, I have no questions about that. In these 4.3 TBI trucks, they use the same computer as a full size chevy truck of the same year, with a different chip. So, if you pull a 350 from a full size, drop it in the S10, put in the chip from the full size, everything works perfectly and the S10 just thinks its a full size. Same wiring harness, all accessories bolt right up.
My question is this... is a stock TBI sufficient for a stock L98 motor? I have an L98 sitting on a stand in my garage, sold the camaro it was going in. I have a TBI intake for a 350. If I bolt this intake on the L98, everything will bolt right up in my S10. So will the TBI setup starve the L98, or will it run ok? I understand that I will need to do some tuning to get the most out of it, but I first need to know if I should even bother with putting this injection on this motor. Has anyone used this combo?

 

Yep, there are some people on here with TBI on L98s. I'm sure they can tell you more than I can, though, but I'll try.

Pretty much. The only parts you'll need are the usual 350 swap parts to make the TBI work right. 350 PROM/chip, 350 ESC module, 350 knock sensor, and 350 injectors.
It will probably run decent with the 350 chip in it, but it's just like you said, it's definitely going to need some custom tuning. But, as long as the TBI system is tuned properly, it won't starve the L98 at all. Heck, the stock TPI system starves the L98 at higher RPMs.

But, like I said, I'm sure the guys with L98s under their TBI setup can help you more than I can.

 

We will pretend that you are doing a 350 TBI swap into an f-body to keep it legal. Your swap would be no different for anyone doing a 350 TBI swap.

Benm is right on. Your biggest concern will be fueling. You won't be able to feed the motor with 4.3 or 5.0 injectors. There are a few 350 injectors you can use as well as certian big block units. For the sake of tuning and using a 350 truck prom I would stick with 350 injectors.

 

Thanks guys

 

I was told that you should get chip because the L98 engine is a lot different then then L05. I did pretty much the same swap put a L98 into my camaro and started with a 305tbi. Kept the tbi and and changed the chip, esc, and knock sensor. I was told the L98 came from the factory rated for 245hp and like 3?? ft/lbs and the LO5 was rated at 190hp and 3?? ft/lbs so there is a pretty big difference. If you call Brian at Tbichips.com he can help out with the chip if you don't have one he burnt mine and I have been nothing but happy.

Bill

 

I can't use a chip from a thirdgen, since its a truck and uses a completely different computer. The chip I am using comes from a full size chevy truck with a 350. What are you guys referring to when you say "ESC"?

 

electronic spark control module... they are different between 305/350's and btw, i use 55# injectors and they work just fine... might wanna use 65's if you intend on beefing the motor up..

 

Stock for Stock TPI will outperform TBI. The L98 you have now is probably around the 200hp mark as it sits. Some LO5's had the L98 cam and their heads flowed nearly identical to L98's. They were very similar motors with thier power outputs varied because of their different inductions.

 

Which years and models? If I knew that I probably would of just looked for one of those. LOL!! Would of made things much easier.

Bill

 

So ESC is the same thing as the ignition module in the distributor?
I'm not going from 305 to 350, I'm going from a TBI 4.3 V6 to a TBI on an L98. I've already got the intake manifold and TBI unit off of a 1500 full size truck with a 350

 

The ESC mounts to the firewall on the drivers side.

 

Is your trans an auto or stick? If it's an auto it is probably controled by the pcm. Do pcm's have replacable chips or do you just flash program them? I don't know what year GM stopped using removeable chips and started flash programing.

Steve

 

If I am not mistaken I am pretty sure the computer only controls TC lock up on 3rd gens. The 4th gen 4l60E (700R4 with electronically controlled shifts) was the first to implemented a true PCM in an f-body. I could be wrong.

 

The TBI and TPI are not much different in horsepower if they were bolted on the same engine. IMO the TPI is actually more restrictive to HP especially on the high end. The L05s that had the L98 cam were still so choked by the exhaust GM stuck in them (pellet style cat, 2 1/4 pipes, log style manifolds, and stock restrictive muffler). My 1992 L05 had the 305 peanut roller and the most horrid exhaust you could imagine (from a 1992 van 2 1/4" exit van logs, 2 1/4 to 2.5" Y, 2.5" pellet style cat, anda single (2 1/2" in and dual 2") outlet restrictive stock muffler. It still made 200 RWHP @ 3,700 and 315 ft/lbs @ 2,500 when it was completely stock though. A full exhaust, headers, a LT1 cam, and tuning; brought the total to 279 rwhp @ 4,900 and 342 ft/lbs @ 3,400.

 

like you said, it has one of the later PCMs, which can also run TBI. It may be as simple as swapping in another calpack or whatever they use. There is one snag, the trans may use a different number of frictions then the V8 one, which would necessiate taking it apart to replace/add clutches to fortify it. Some other mods wouldnt be a bad idea, either. I pulled a 700-R4 apart, it wasnt too terribly bad. Getting it out of the car was the worst part for me. of course, I have to do this again since the TC took a dump