tbi chevy cams

drifter · Post by **drifter** » Tue Nov 20, 2007 6:31 pm

Needforspeed what do you mean by tune the computer? What has to be done to get it to run right?

needforspeed66gt · Post by **needforspeed66gt** » Tue Nov 20, 2007 9:05 pm

Just like tuning a carburetor, you need to adjust the fuel and timing tables to make the engine run at a safe and efficient air fuel ratio. Anytime you make a change that adds airflow to the engine you need to adjust the fueling.

drifter · Post by **drifter** » Wed Nov 21, 2007 12:29 am

how do you make changes to the factory computer

needforspeed66gt · Post by **needforspeed66gt** » Wed Nov 21, 2007 2:12 am

You need to find someone with the software and a dyno - the standard HP Tuners, SCT, etc systems will not work with the old gen computers, I don't know the program that's used because we have a customer that does the calibration work for us on the old TBI stuff. We use HP Tuners, LT1 Edit, and SCT in-house for all the newer generation cars.

RogerF · Post by **RogerF** » Wed Nov 21, 2007 8:25 am

how do you make changes to the factory computer

I have used this software in the past on the GM TBI ECM's.

http://www.tunercat.com/tnr_desc/do_tc.html

You will need a chip burner, and the chips. Both are readily available.

There are several good tutorials on how to do it posted on the net as well.

F1Fever · Post by **F1Fever** » Wed Nov 21, 2007 10:47 am

profile.php?mode=viewprofile&u=874

don2 · Post by **don2** » Wed Nov 21, 2007 11:23 am

My daily driver is a 383ci tbi running Vortec heads, GMPP tbi intake, big block throttle body, 1 5/8 longtube headers, and a Comp cam with 230/236 dur. at .05, 112 lsa, and .608 lift with 1.6 ratio rockers. As was mentioned earlier, with proper tuning tools, the door is wide open for a cam. I personally use Tunercat RT which with Craig Moates Ostrich emulator, allows for real time tweaking of the ecu. Works especially well with an Innovate wideband sitting there. Another very capable tuning program is TunerPro by Mark Mansur. My ecu is a 1994 vintage with transmission controls which makes it a little more capable than some of the early computers, but people don't give the TBI setup enough credit for its capability. It is all about tuning the setup properly.

Btw, it idles great at 700rpm, has great throttle response, and runs closed loop with no problems. So don't let anybody tell you the cam is too much for the tbi setup.

gmc406 · Post by **gmc406** » Wed Nov 21, 2007 4:02 pm

don2, I agree with everything you said 100%. There is more unleashed HP in a TBI setup than most people give them credit for. You just have to know how to work with them. The system is cheap, effective, simple and efficient. At one point, I was tempted to remove the injection and thow a carb on it. I'm glad I didn't(not saying that a carb isn't a good setup either, I don't know much about how to tune carbs).

needforspeed66gt · Post by **needforspeed66gt** » Wed Nov 21, 2007 8:50 pm

Removing the TBI and a ported edelbrock intake - swapping to a Performer RPM air-gap and 750cfm 4150 is good for 40-50 hp.

482OLDS · Post by **482OLDS** » Wed Nov 21, 2007 9:11 pm

I keep thinking of trying a carb and a HEI now that Illinois has scrapped it's smog inspection on 96 and older vehicles...

I wonder if I could get better than or even keep the 14/15 mpg it gets now and a nice gain in power too???

My TBI isnt tuned to perfection by any means. But its close, with the stock 350 it was 15/17 mpg...

mallow415 · Post by **mallow415** » Wed Nov 21, 2007 9:23 pm

I'm also trying to get some more power and some better mpg out of my 94 3/4 4x4 that i pull my race car with. Just got back from hunting pulling my single axle trailer with a 4wlr and got 9mpg. The best it has ever got unloaded is 14. It diffently needs some help and could diffently use some pwr. Have been thinking of doing a 383 with a sprtII heads and performer intake with a tbi adapter that i have the heads sitting around a rotating assebly. This thread is something that i have been looking for. Keep up the good work fellas.

af2 · Post by **af2** » Wed Nov 21, 2007 10:16 pm

mallow415 wrote:I'm also trying to get some more power and some better mpg out of my 94 3/4 4x4 that i pull my race car with. Just got back from hunting pulling my single axle trailer with a 4wlr and got 9mpg. The best it has ever got unloaded is 14. It diffently needs some help and could diffently use some pwr. Have been thinking of doing a 383 with a sprtII heads and performer intake with a tbi adapter that i have the heads sitting around a rotating assebly. This thread is something that i have been looking for. Keep up the good work fellas.

Not trying to be a smart ass! Cummins is the answer, 19 MPG freeway with race car, 14MPG running service calls in the foothills.

needforspeed66gt · Post by **needforspeed66gt** » Thu Nov 22, 2007 1:55 am

482OLDS wrote:
I wonder if I could get better than or even keep the 14/15 mpg it gets now and a nice gain in power too???.

LOL - I should add that while we picked a big chunk of power with the carb conversion, the MPG dropped significantly - I forget the number, but you will never get the MPG out of a carb setup that you can do with EFI.

This was our dyno guy's personal 1/2 ton truck, so we had plenty of play time with it.

With just our 383 TBI package, fuel mileage will actually increase a bit if you can keep from using the extra power all the time

gmc406 · Post by **gmc406** » Fri Nov 23, 2007 9:28 pm

needforspeed66gt, you talk about your 383 TBI package. How is it put together? Just interested thats all, cause you say you gain 40 ponies by throwing on a carb and intake. That's a nice increase, but in my application I feel the power would go the other way.

needforspeed66gt · Post by **needforspeed66gt** » Fri Nov 23, 2007 9:48 pm

Scat 3.75" stroke crank
Manley 6.0" rod
Wiseco pro-tru pistons
World Sportsman II(Only heads with an EO Number for smog) with our comp VJ and bronze guides, some light port work
Isky springs/retainers
big block injectors in the TBI unit
Comp roller cam/Isky rockers
Champ pan for oil control
Edelbrock headers (EO number on TBI trucks)

All brand name stuff, no cheap PBM type parts where you don't know the origin.

Makes 100hp over stock, passes CA smog, and drives/idles like a stock motor.