496 vs stock TBI?

[bablazer73]

My 88R30 has 100k on it. as far as my history of the truck goes, all original, but well maintained. But It is lacking power for what I'm hauling. I would prefer to leave the truck as stock as possible and use the stock TBI. I've been tossing around the idea of rebuilding another 454, and doing some mild upgrades. bump the compression up to 9-1, small hydraulic roller, maybe Holley TBI, and Edelbrock intake. not looking for high RPM, all under 4,000 RPM.

What's your thoughts on throwing a stroker crank in, or just using a 502 short block? do you think the stock TBI would still work?
Any experiences??

 

[obijuank5]

It might idle.

 

[bablazer73]

It might idle.

well, that's not optimistic!

 

[sweetk30]

be a full custom chip burnt with tuning time to get it right . def a bigger tbi like you planned .

if your dead set on tbi call howell efi the tbi chip guy has been there for over 20 years doing them . he can tell you yes or no .

otherwise aftermarket system will be better .

 

[jekquistk5]

I would do a tbi unit but use FItech, fass, or holley. It might start and idle, but it will run like crap, especially if it has any sort of cam in it.

 

[sweetk30]

by the time you do one of them and want timing control and a super smooth running setup dont forget to look at the pro flo 4 system . and its full sequential port injection .

i can idle my 350 down to 500 rpm and its still smooth as can be on the pro flo 4 .

but each to there own and there specific requirements .

the aftermarket tbi units are ecm built in to the unit so if it dies there is no easy fix . now i just made a thread the other day showing fitech has started separating them .

 

[bablazer73]

I would do a tbi unit but use FItech, fass, or holley. It might start and idle, but it will run like crap, especially if it has any sort of cam in it.

Comp Cams make a couple retro fit style Roller Cams that will work with the TBI, they have a 114 centerline 268/270. I've used them before.

 

[bablazer73]

by the time you do one of them and want timing control and a super smooth running setup dont forget to look at the pro flo 4 system . and its full sequential port injection .

i can idle my 350 down to 500 rpm and its still smooth as can be on the pro flo 4 .

but each to there own and there specific requirements .

the aftermarket tbi units are ecm built in to the unit so if it dies there is no easy fix . now i just made a thread the other day showing fitech has started separating them .

My problem is more the aftermarket support. I spent so much money on the old blazer, with the 4BBL Holley Projection, which ran fantastic!, but I got 2 years out of it. When the ECU popped, I sent it back to Holley, who told me they no longer supported the system, and wanted me to buy a whole new unit. Left me with a non-running truck, and 1,000 bucks thrown away. I like the everyday reliability of EFI, but just with any "hi-tech" component these days, here today, gone tomorrow....

 

[6872xtc]

I would start by talking to Howell EFI as @sweetk30 suggested.
The problem that I had with the TBI on my '90 after I swapped parts on the engine that was running previously with TBI, was that when I did a data-log and sent it in, he said that it looked good, even though I couldn't really drive the truck because of how poorly it was running.

I went with Edelbrock PF4 and feel that since GM uses it on one of their crate engines, hopefully I will have good luck. Not positive and time will tell.
I like that the ECM is remote mounted as well as some other aspects, but it may be giving up some down in the low rpm range. However, I can drive my truck and change things in the time easily, plus it seems to have some OEM parts in the mix.
Research as best as possible before buying anything.

 

[86454K30]

A guy here in town built a nice 496 for his 93 K2500. I asked what injection he was using and he had a "plan" to make the tbi work using CFM-TECH parts and a custom chip. Engine didn't make 500 miles and it now has a holley sniper on it. Bottom line the TBI is great for driving but, does not provide enough air or fuel to build horsepower or sustain a big motor.

 

[mrk5]

Problem is you can find people that have positive and negative experiences with all EFI systems. There are so many variables that who knows how much is user error and how much is manufacturer error.

The obsolesce thing is a pain in the neck but I don't know if you can avoid that either. We run into with our $20,000 equipment for the sign shop. Some manufacturers will support old equipment for several years and others drop the old stuff as soon as the new thing comes out.

Like @6872xtc said, a lot of research is needed. You have to read sources you trust and kinda go with which you feel will be good. My current thoughts are the price of a FiTech or Sniper make it a good option for an occasional driver. I think if it's going to be driven a lot, a more expensive system with divorced ECU might be more reliable. At the very least if something happens to the ECU, you're not sending back an entire throttle body for warranty repairs. And then maybe this new FiTech with the divorced ECU will be a good option for the low cost TBI type system.

 

[1-ton]

Building another 454 with a compression ratio in the 9.5:1 range would be the biggest thing you could do to make more HP. A small cam that increased the duration about 30-degrees and 20 to 25 thousands of an inch more lift than stock would also help. These are the main things that will increase HP some.

Comp Cams makes camshafts that are OBD-I computer friendly. They are single pattern camshafts with a wider lobe separation that keep the vacuum fluctuation down so that the MAP will not go crazy. You can rebuild the stock TBI and injectors. Make sure the throttle shaft is rebushed so it does not have any vacuum leaks.

The stock GM 454 TBI has a 2" wide diameter bore just as the Holly direct replacement TBI does, thus the Holley TBI does not increase performance. The Edelbrock aluminum TBI intake manifold will also not increase performance over the stock GM aluminum intake manifold. I have read some flow numbers between the stock GM TBI intake and the Edelbrock TBI intake, and the difference is small.

Along with a good flowing exhaust system this is about as much as you can do to a TBI engine to get more power out of it. Unless you are willing to spend more money, time, and effort with newer OBD-II technology or a complete aftermarket fuel injection system OBD-I is a limited platform to work with.

 

[bablazer73]

Building another 454 with a compression ratio in the 9.5:1 range would be the biggest thing you could do to make more HP. A small cam that increased the duration about 30-degrees and 20 to 25 thousands of an inch more lift than stock would also help. These are the main things that will increase HP some.

Comp Cams makes camshafts that are OBD-I computer friendly. They are single pattern camshafts with a wider lobe separation that keep the vacuum fluctuation down so that the MAP will not go crazy. You can rebuild the stock TBI and injectors. Make sure the throttle shaft is rebushed so it does not have any vacuum leaks.

The stock GM 454 TBI has a 2" wide diameter bore just as the Holly direct replacement TBI does, thus the Holley TBI does not increase performance. The Edelbrock aluminum TBI intake manifold will also not increase performance over the stock GM aluminum intake manifold. I have read some flow numbers between the stock GM TBI intake and the Edelbrock TBI intake, and the difference is small.

Along with a good flowing exhaust system this is about as much as you can do to a TBI engine to get more power out of it. Unless you are willing to spend more money, time, and effort with newer OBD-II technology or a complete aftermarket fuel injection system OBD-I is a limited platform to work with.

I've used the Comp cams hydraulic roller computer cams before. worked great. The truck has headers and dual exhaust on it already. I'm not looking to make a ton of power, just more. it sounds like just rebuilding a 454, bumping the compression, roller cam, maybe rockers, is about all I can do.