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Need some opinions on EFI(which route to go)

Discussion in 'The Garage' started by Emmettology 101, Dec 2, 2002.

  1. Emmettology 101

    Emmettology 101 3/4 ton status

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    Hello all!

    I have an 89 GMC 3/4ton(heavy Half) 4wd. It has a 383 that had the original TBI on it but my friend swapped it out for a carb. I would like to go back to EFI, but am debating on what system to go with.

    My choices are: TBI, TPI, or LT1 style.

    Pros and cons I have come up with...

    TBI: I have the stock harness(still in truck), comp. and intake. Only thing I would need is a Throttle body, but another friend of mine has the one from this truck, so I may be able ot get it off of him. SO basically I have everythign for this system except I would need to get a chip burnt for the specs of the 383.

    TPI: The only thing I have for this type of system is a computer from a Vette(under the hood comp). I can get a TPI harness pretty cheap compared to some of the larger companies selling them. But I would have to buy a harness, intake set-up, injectors, etc... I would need close to $275 for the harness plus around $250 for the injection(from Ebay)...

    LT-1: (A)(stock) I have the intake, injectors, Opti-spark, comp... Only thing I would need for this set-up is a harness and some misc. small parts...

    (B)(modded) THis set-up would need a little outside work. I would still need a harness, but one form a TPI set-up(about $275)and change a couple sensors. Then I would need to have the intake drilled for a disty and a small spacer welded to it. There is a guy on the net that can do this for around $250...

    The TBI is a quick and less expensive route, but will I be gaining more HP if I go with one of the other set-ups?

    This truck has a high comp 383 in it and is used primarily for a daily driver with some towing. No wheeling....

    Any opinions? /forums/images/graemlins/ears.gif /forums/images/graemlins/laugh.gif
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'd go with the TBI...K.I.S.S./forums/images/graemlins/cool.gif Sure the TPI and LT-1 set-ups will make better max hp, but it will come at a price dollar wise and aggravation wise. I would think a healthy 383 with TBI should make plenty of power for your needs.

    Rene
     
  3. Emmettology 101

    Emmettology 101 3/4 ton status

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    Thats the route I am leaning towards for now. Cheap and easy. Since I have most of the LT1 stuff, I may hang on to it and then piece it together. Then once I have a complete set-up and better know how of the different systems, maybe I'll swap...

    The carb'd set-up isn't bad except for these cold mornings when it doesn't want to start...
     
  4. Derf00

    Derf00 1/2 ton status

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  5. Emmettology 101

    Emmettology 101 3/4 ton status

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    Well I wanna keep this on the cheaper side. Especially since I have a few parts to each of the systems from the factory. And factory parts will be easier to come by. But thanks! /forums/images/graemlins/smile.gif
     
  6. Suburbanite

    Suburbanite Registered Member

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    I agree with tRustyK5, KISS.

    Besides, based on a DD2000 simulation there's little difference in max HP/TQ #'s. At least for the 383 I've computer 'built'. I used the program to specify best specs for torque in the 2K-4K range & max TQ(flywheel) is 505ftlbs at 2K rpm (lowest rpm graphed, & TQ falls off from there) & max HP is 382HP at 5K rpm. Don't know enuf about engines to know if the specs produced by the program are realistic so ... Basic setup is with 650cfm TBI (454 TBI spec, I think. CFM has very little impact at lower RPM's. E.g., dropping CFM to that of 350 TBI, ~540, only lowers max HP/TQ by about 10/3, respectively); large tube headers with mufflers; low performance heads with standard valves & pocket porting; stock street/economy roller cam with .45 lift on both intake/exhaust; but a whole lot of compression at 11:1 (plan on running stock heads but ceramic coating piston tops, chamber, valve heads, part of valve shafts, intake/exhaust head passages, intake runners & bottom of intake manifold).
     
  7. BobK

    BobK 1/2 ton status

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    TPI's are nice but if you have anything other than a stock spec'd eng. it would requier some chip burning.That is time consuming and/or expensive if you have to have some-one else do it for you.
    Are TBI's more forgiving for modified eng.'s?...I'm not sure.They still have a computer controlling them.
    If you want cheap and easy,a carb would be your best best with a modified eng.
    My opinion anyway. /forums/images/graemlins/grin.gif
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I don't find DD2000's numbers to be very realistic. I doubt there is a smallblock out there cranking out 505 ft/lbs at 2000 RPM. Those are diesel numbers...

    Rene
     
  9. TopOff

    TopOff 1/2 ton status

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    I am running the TBI on my 383. I like the K.I.S.S. too.

    I am in the process now of creating a custom chip. With my 9.5:1 compression ratio I have a little ping with part throttle. My TBI is quite a hybrid animal though.

    It is a Howell TBI unit. This came with a Holley 4-barrel 750CFM TBI unit, and a LT1 TPI computer w/ standard HEI (springweights and vacuum advance - non-computer controled). /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/tongue.gif

    For added safety/recover I purchased an additional fuel-pump, chip, and computer. /forums/images/graemlins/shocked.gif

    I have recieved quite a bit of information from both diy-efi.com and thridgen.org.

    Hence, I will be re-programming my chip (more POWER!), and adding the computer-controlled HEI soon.

    Good luck.

    **** I forgot to add, I would stay away from a MAF based F.I. unit. These are expen$ive, tend to break when the get water in them, and the speed density units can be programmed to accept more parameters. /forums/images/graemlins/grin.gif

    Anyone selling a computer-controlled HEI - cheap?
     
  10. JK5

    JK5 1/2 ton status GMOTM Winner

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    "TBI" /forums/images/graemlins/thumb.gif

    A throttle body runs $35 to $45 bucks in the bone yards around here.....

    That's what I have on my 454 on my 2500....it has 200,000 miles on it......AND I get 17 miles to the gallon....when I MILK IT!!!

    You may have to buy a chip!!!
    Do you still have that Pinging noises?
    Does it have Headers?
     
  11. BurbinOR

    BurbinOR 3/4 ton status

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    TBI sounds like the best way in your situation. TPI is nice, yes, and has the wow factor when you pop the hood but for the extra bucks you would have to lay out (chip and fuel pump at minimum) above what you listed you might not get the bang for your buck. I'm heading back to TBI shortly so I anticipate deciding down the road if I want to hop up the 350 in a Burb, build a 383, 400, TPI it, or go BBC............so many options.

    For your daily driver, I'd stay TBI. Just my $.02 /forums/images/graemlins/burb.gif
     
  12. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I just forked over the deposit for my 454's EFI kit from www.customefis.com a month or so ago. Since I'm coming from a QJet, I think ANY EFI system will be a WORLD of improvement! I too chose the TBI system after quick consideration of the KISS theory, and the fact that my wallet can't even come close to hacking a TPI system for a BBC! /forums/images/graemlins/blush.gif /forums/images/graemlins/rolleyes.gif

    Good luck with your decision!

    -Dan
     
  13. 4x4Freak

    4x4Freak 1/2 ton status

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    What does KISS stand for?
     
  14. fortcollinsram

    fortcollinsram 1/2 ton status

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    Keep It Simple Stupid...
     
  15. Bullet

    Bullet 1/2 ton status

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    Just curious, but how much does a TBI conversion run? The ones I've seen are the $700-$900 range, the same price of the MPI conversion, like Derf00 posted. Please, correct me if I'm wrong...
     
  16. azblazor

    azblazor 1/2 ton status Premium Member

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    Complete TBI setups can be had at junkyards for 300-350.
     
  17. Emmettology 101

    Emmettology 101 3/4 ton status

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    You have a 3/4 ton with a 454? Where you hidding that beast? /forums/images/graemlins/smile.gif
     
  18. Emmettology 101

    Emmettology 101 3/4 ton status

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    I am going to need to get a chip burnt for the TBI also... I will be runnig a holley TBI unit and the stock comp. IT ran good beofre with this set-up, but needed a chip burnt ot get max power.
     
  19. Emmettology 101

    Emmettology 101 3/4 ton status

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    So you are runnign an LT1 comp with an old style, non-comp controlled HEI right now? Hmm... Hows that set-up run?

    I have everythign from the stock set-up with the addition of a Holley TBI(yes, my one friend who has it said I can put it back on)... It ran great this way but did need a chip burnt.

    I am going to have to head over ot Third-Gen and DIy-efi. Thanks!
     
  20. Emmettology 101

    Emmettology 101 3/4 ton status

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    Well if I went LT1 style.. I have the intake, injectors, comp, and opti-spark. I would only need a harness. But if I went this route I would eliminate the opti spark and go with a disty....

    I have everything for the TBI now too. This will definately be the cheaper route since all I would need to buy is a custom chip!(but I wouldn't need it right away)
     

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