Why no TBI Engine thread?

[budviper1962]

Getting my 94 z71 5.7 tbi rebuilt just going with rv cam, the guy building it is grinding heads and opening the ports for more air, edelbrock intake, still deciding on throttle body, but headman long tube, and 3” exhaust is going to help

 

[Nad_Yvalhosert]

If I never need info on such a low tech, robust, and simplistic system, I choose to float between here and the F-body site. They try to get every ounce of power for them funny looking 2wd sporty non trucks.

 

[Schurkey]

A separate TBI thread will catch a giant heap of careless posters who want advice on their brakes, transfer case, dash lights, etc.

It will also capture lots of folks who want generalized engine info that isn't TBI-specific, but happens to apply to TBI engines--starter motors, fan clutches, engine mounts, exhaust mods.

I think a separate forum for TBI is a bad idea.

 

[PlayingWithTBI]

I'm enjoying to see what others want to do/are doing to their TBIs. Hopefully folks will keep it to equipment or modifications which are only germane to this platform.

I have the EBL Flash-II ECM and a WBO2 with which I'm happy. FYI here's a thread dedicated to the EBL, 99 pages and still going

Tuning with the EBL - Third Generation F-Body Message Boards

DIY PROM - Tuning with the EBL - Hey can we start a thread for EBL tuning. The EBL thread is grown rather large and was pre release. All of us that are using the EBL could share our results and tweaks. RBob would have a place to vist on his own time and help those that need advice using his EBL...

www.thirdgen.org

 

[DerekTheGreat]

I know you! You're one of those people that uses your truck as though it were a truck. Practical, sensible and adult like. I agree with you. I didn't know anything about TBIs when I bought my clean and stock 1993 K1500... ...The worst aspect is the gas mileage.
...I don't know what the original mileage was supposed to be when new but mine gets between 10 and 12 MPG...
...So what can be done to improve the economy of the TBI?

I wouldn't know about that. My '89 K1500 regular cab shortbox with it's bone stock 350 TBI & 5 speed manual transmission will net 19.xx mpg on the freeway. Stock tire size, 3.73's. It must have lean cruise enabled or some other PROM chip, was from New Mexico. I'd say swap it to a stick shift for better MPG. I have a 305 TBI equipped Firebird, it has an automatic, yet that thing used to pull 24 mpg before I slapped Trick Flow cylinder heads and the Edelbrock performer #3704 intake on it. Now it pulls a bit harder than a 350 TPI car, yet returns 22 mpg.

 

[C30454]

I know you! You're one of those people that uses your truck as though it were a truck. Practical, sensible and adult like. I agree with you. I didn't know anything about TBIs when I bought my clean and stock 1993 K1500. I 'm pretty happy with it but the performance wasn't what I expected from a Chevy 350. Rummaging through lots of bad information I finally understood that Chevy built it this way for reasons that Tom elucidated. It's a truck engine for a fairly light duty full size truck. It gives you the reliable low end torque and it is low maintenance. The worst aspect is the gas mileage.

I'm glad I didn't modify it. I don't know what the original mileage was supposed to be when new but mine gets between 10 and 12 MPG. With the current gasoline reality I'm very interested in whatever will improve the mileage.
So what can be done to improve the economy of the TBI?

What rear gear do you have?

How old is the O2 sensor?

You could try disconnecting the EGR valve for a tank or two, that may help a little.

Make sure timing is up to *****, and even add 2-4 degrees.

How big are your tires? Larger diameter tires will actually cause you to travel further than your odometer records, falsely skewing mileage numbers lower than actual.

Is overdrive working and the TC locking up?

You can save a lot of fuel if the traffic patterns allow a more gradual increase in speed.

I don't know what a 350 K should get, but my buddy's Dad used to coax 19 on long family trips out of a '73 Chevy wagon that of course had no overdrive.

I get 12.2x with my 1 ton 7.4 4.10 crew cab around town. Although my around town is semi rural so it's not the same as city driving. I would think that the 350 K motor should be able to do a little better.

 

[DerekTheGreat]

Make sure timing is up to *****, and even add 2-4 degrees.

I'd advise against that. Last year I messed around with it after reading around here. Sure enough, the extra advance I gave it just got pulled out by the computer. All I saw were increased knock counts. I still see knock with the timing at zero. I'm not smart with this stuff, but something tells me because of that, it's good where it is.

 

[Outlawborn]

I have the GENV 454 (1995 ECLB C3500 Bone stock, 118, 000 on the clock). It's a dog for sure. Would love/need more power. Part of me wants to keep it period correct as much as possible and stock looking but I want to grin when I mash the go pedal. Trying to figure out if I should keep this engine and do the TBI mods, etc or go heads, intake, cam, and new fuel system. Do I pull it and build it or go crate motor? It's a tow pig so how far can I go with what I have now vs, what is realistic for this truck. That is why I started this thread, so all this great info from you guys is right here.

Good luck on finding a decent crate motor. I've been trying to swap out the 5.7 for a 383 and everything is back ordered and no real idea on when or if these things will be in production anytime soon. Called gm performance, atk, blueprint. No luck

 

[PlayingWithTBI]

I've been trying to swap out the 5.7 for a 383 and everything is back ordered and no real idea on when or if these things will be in production anytime soon. Called gm performance, atk, blueprint. No luck

Maybe make your own 383? Take your 5.7, bore it 0.030" over, throw in a 400 style crank, maybe flat top pistons, a roller cam, a 7.4L TB, and some tuning

 

[L31MaxExpress]

I'd advise against that. Last year I messed around with it after reading around here. Sure enough, the extra advance I gave it just got pulled out by the computer. All I saw were increased knock counts. I still see knock with the timing at zero. I'm not smart with this stuff, but something tells me because of that, it's good where it is.

I have run 6°+without knock retard on them. I have run them as high as 10° with premium fuel eithout knock.