Fast355

iTrader: (2)

No, it was a factory 3.4 MPFI intake from a 1994 Camaro swapped on to the same 3.4 that was running the 2.8 TBI with 305 injectors at the time.

Kevin91Z

iTrader: (1)

Look at YOUR post again that I responded. You basically said you didnt care how much we have been messing with TBI, that only Fast355 knows TBI and we dont. That's a slap in the face to our knowledge and of course I'm going to defend myself. My dad was a big TBI promoter in the 90's. He converted his '77 Chevy truck from carb to TBI using a complete engine and trans from a 1993 L05 truck. And he converted his '81 El Camino from LG4 to L05 TBI, too. The vehicles were great cruisers and got good gas mileage, just like they were designed to do. He still has that '93 TBI engine but its now in an '88 Chevy truck. I bought a '92 RS and we were going to build that up and run fast with it until we found my '91 Z28. So my dad took back the '92 RS and said he was going to build a TBI engine to beat my TPI one. But, as we learned TPI and saw the gains we made with TPI, we realized the biggest problem with TBI was the slow, basic ECM. 4 kilobytes of TBI prom is tiny compared to the 128 kilobytes and 256 kilobytes you get with the TPI proms. It wasnt until 1993 that the TBI computers were upgraded to 256 kilobytes and were finally easy to modify. My dad and I were in the process of trying to run TBI on a 7730 TPI computer, but realized we wouldnt be successful because the TBI is dual-fire and the TPI is single fire. It took cranking the fuel pressure up to 55 lbs and installing 72 lbs injectors before the engine would even get enough fuel to idle. And if you rev'ed it, it would die. So, rather than convert the wire harness back to the TBI computer, we pulled off the TBI intake and put a TPI one on. He wanted to do the cam swap then, but I convinced him to put it back stock so we could get a true comparison of the difference between a TBI and TPI engine. This was five years ago back in 2001. So, yes we do have quite a bit of knowledge about TBI, but we gave up on it once we realized at the time there was more potential and more support for the TPI setup.

Ok, no laughs here, but did you dyno it? With that V6 combo, I seriously doubt you would see more than a 5-10 horsepower difference. How about fuel economy, any change there?

The original poster wanted to know if it was worth it to swap to TPI, and I gave my opinion and backed it up with facts. Then we get slammed and my facts called bogus because someone else had better luck with TBI than we did.

MikeDirntRulez

I apologize Kevin. I didn't know of you and your Dad's knowledge on TBI. I just commented that Fast knows what he is talking about, and that's why he comments (because basically somebody told him he should shut up and that he talks too much). I realized you and your Dad were knowledgeable in TPI, but didn't know about the TBI.

Again, I am sorry if I offended you or Don, as that was not my intention .

Fast355

iTrader: (2)

The TBI ecm maybe slow and basic, but it is still light years ahead of a carburetor or mechanical fuel injection setup in terms of efficiency and emissions which it was designed. I know they are slow, but the EBL helps with that alot. With RBob's new peformance oriented code the TBI ECMs actually run much smoother, give instant throttle response, idle better with cams, etc. 224 @ .050 in a 305 with about 105 lb/hr per injector of fuel and 6,500 rpm was easy.

I also tried to run a TBI on a PFI ECM and was able to make it run pretty decent though. I was running a 749 wired sunbird style and 2 bar MAP with 305 injectors in a 2.8 TBI unit on a 3.4. I then swapped it to MPFI intake from the same RWD 3.4. I lost 1 mpg highway converting to MPFI, but gained 1.5 mpg city. Track numbers showed nearly no difference in performance.

I've backed it up with facts and personal experience as well, and been called out on it. I will maintain that the factory speed density programming in a TPI will not run a stock L03 well at all. I KNOW the factory speed density L98 programing made a 1992 350 TBI truck run like crap and make less power than stock. After programing we were able to get about 5-10% more torque from 2,500-3,500, but I stress AFTER programing and at a loss of low-speed torque.

If you were so worried about defending yourself, why was this the first thing out of your mouth. You are basically trying to discredit all the Carb/TBI/MPFI work I have had.

Dyno Don

iTrader: (7)

Not really, the original poster simply asked if it was worth it. The correct answer was Yes....with explanation
Then you decided to do a disertation of your experiences with TBI which in the end has made this whole thing worthless and a waste of bandwidth.

[quote=vipershark11]
the set up is only costing me 250 no installation or anything cause i know mechanics very well. and im not selling my car after all ive done to the body interior etc etc. i just want the tpi maybe get a bit of a gain thats it i just want to be happy plus i want it to look clean under the hood not with the huge spaceship looking thing.


[quote=Fast355]
Its NOT worth switching to TPI on a stock TBI long-block. You will have about the same power with a mass-air TPI setup. With a Speed Density setup, you are likely to lose power! I will maintain that swapping to TPI is about worthless from a performance stand point. Stock TPI engines make more power because of the cam, exhaust, and ECM tune. They have better performance because they have more power due to the cam/exhaust, have better gearing, bigger tires, and usually a posi.

I'm done

Fast355

iTrader: (2)

I will maintain my opinon. It is NOT worth swapping on a stock engine unless the original poster just wants the look of TPI. What makes you think yours is the correct answer, (in science the results of 1 experiment are not enough to create a scientific law, it will create a theory) and that is where we sit. It is tough to say that one way is better than the other. I have done similar test to you and LOST HP/TQ in certain cases and seen next to no gain in others, I have seen good gains on some though, so it is hardly proof that you are absolutely right. That is my whole point, my opinon still stands, if you want TPI buy a TPI car and enjoy all the benifits of the Z28/Iroc/Formula lines.

Your TBI L03 should have been around 240-250 ft/lbs @ 2,500 STOCK and about 270 ft/lbs with the L98 exhaust on it.

The last L03 truck engines(detuned at that) were making 175-180 FWHP and 275-280 ft/lbs of torque at the flywheel.