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TBI engine limitations?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by DukeBoy88, Jan 16, 2003.

  1. DukeBoy88

    DukeBoy88 1/2 ton status

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    I'm currently installing axles, and thinking ahead to rebuilding my engine. I was looking at 383 stroker kit, drooling actually, and I wanted to know if my TBI could feed a 383 making around 350hp 400tq. I'm currently using a Holley replacement TB rated at 670cfm on my tired 350. Holley lists the same TBI with a standalone system for engines making up to 275hp. with proper programing and possibly increased fuel pressure from a new pump and turbo city regulator what are my realistic limitations to making power. I'm asking cause for now I want to retain my TBI and control of my TH700r4, so I don't want to invest money in an engine that I can't fully utilize, I would just rebuild my 350 instead. thanks in advance.
     
  2. u2slow

    u2slow 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    retain my TBI and control of my TH700r4

    [/ QUOTE ]

    I think the only thing your ECM controls on your tranny is the torque-converter lockup (if anything at all). They used the TH700 before they had ECMs and fuel injection, so there must be a way around that.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Give the folks at Turbo City a call. They worked with one of the magazines a while back on swapping a GM Crate 383 into a 350 TBI application. They programmed a custom chip and I think they also upgraded to a 454 throttle body for its increased airflow and larger injectors.
     
  4. Thunder

    Thunder 3/4 ton status

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    I dont know about the Holley units. But I am not impressed with holley FI.
    I like the stock units.
    Out of the stock Rochester TBs you can get around 300 HP out of the 350 1 11/16" bore Throttle bodys
    And you can get around 400 Hp out of the 454 2" bore Tbs ( big block chev)
    This is assuming your engine is built to be compatable with the ECM. and the TB is modified to flow more air/fuel.
    As said above give turbocity a call they can help you out with the stuff you will need.

    But if you really want a TBI system that makes a lot of power. Go to this page and click Fuel Injection.:Bgfuel.com
     
  5. BigRed89

    BigRed89 1/2 ton status

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    I have an '89 Suburban with a 383 and I am using the stock 350 TBI. I had the TBI rebuilt by JET Performance, and I have a custom chip from them as well. I have had no problems with the TBI, and with my particular combination the folks at Turbo City did not recommend a bigger TBI. Turbo City is definitely the place to call if you have questions. www.turbocity.com
     
  6. DukeBoy88

    DukeBoy88 1/2 ton status

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    Thanks for the info, I talked with turbo city. their regulator doesn't work with my TB and they couldn't program a chip for me, I'll check out JET or maybe Holley. they did answer my other questions. BigRed, did turbo city recomend using your stock TB due to the cam you were using? or just the displacement of the engine? how much power do you think you are making?
     
  7. BigRed89

    BigRed89 1/2 ton status

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    Turbo City's recommendation to me was based on my total combination including engine displacement, cam, heads, intake, vehicle, vehicle use, etc. As far as power output I would guesstimate it to be at approximately 375hp, and 400-425lb-ft tq. I live in CA so I had to keep emissions in mind when doing the build-up as well.
     
  8. Hoover87

    Hoover87 Registered Member

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    Take a look at www.thirdgen.org for a lot of TBI information. It is a camaro page, but the have a great TBI page.

    I just put a 350ho in an 87 truck and kept TBI. A new chip is a must and that will probably be the biggest trick to get right, that and the air/fule ratio. I guess that's pretty obvious, ha. Anyway, I'm using a GM 454 Throttle body with 68lb cop car 350 injectors in it. Caution...the "454" TBI that turbo city sends you will not have real 454 injectors in it. 454 injectors are 80lb, turbo city puts 68lb injectors in...OOOOH, thats why theirs was cheaper. Anyway, they work just fine for the 330 horse 350. The biggest trick will be getting the fuel ratio to be correct throughout the entire RPM range. For example, mine runs rich at idle but a tad lean at wide open throttle. This can be tweaked a bit with fuel pressure. GM makes a vacuum contolled adjustable fuel pressure regulator that will increase the presure as RPM increases. Its only about $35. I recommend getting it. From what I've heard, avoid the Holley TBI. I think the biggest complaint is the injectors. I believe you can put GM injectors on it and it will be fine. The chip I used and am very happy with...especially the customer service is www.fastchip.com. Ed Wright is a great person to work with an will not leave you hanging. Very perfessional service. The price is steap ($350), but I would use hime again. I had to send the chip back once because of turbo city's "oh, by the way" with the injectors. Ed said no problem and reburned it for me.

    Don't get too crazy with the cam you put in it. TBI likes to have vacuum. Anyway, the truck is a totally different beast now. I'm very happy with the project, even with the bit of tweaking I have left to do.

    Mike
     
  9. 4DiggerDan

    4DiggerDan 1/2 ton status

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    Has anybody here used the Edelbrock system to convert a TBI to an EFI? I've personally never done it. I've had customers tell me that it was well worth the money though.
     
  10. GMtrucklover

    GMtrucklover Registered Member

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    All EFI stands for is electronic fuel injection, which is what you allready have.
     

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