TPI upgrade help

Discussion in 'The Garage' started by 89BlazerK5, Jan 7, 2004.

  1. 89BlazerK5

    89BlazerK5 1/2 ton status

    Aug 24, 2002
    Likes Received:
    hi, i have a 1991 K5 Blazer with a TBI 350. i just rebuilt it not too long ago with mostly stock parts.... and, i was thinking of upgrading the top end.

    i want more power, but i don't want to loose my low end torque. i want to be able to tow, but still have power to spin the tires in the mud with my low gearing. i'd like the power & torque curves to be spread out as flat as possible. i'd also like to be over the 300hp mark.

    here's what i want to do:
    L31 Vortec heads w/ Z28 springs & LT4 retainers & roller 1.6 rockers
    SDPC Vortec TPI intake baseplate ( )
    Tuned Port Injection system
    a nice roller cam
    custom chip for ECM


    whats a good cam to run with TPI?? ZZ4? LT1? LT4?

    what runners should i run to improve performance, but not lose my low end torque? Stock? SLP? Edelbrock?

    what do i gotta do to keep the ECM happy? where do i get a chip for it?

    will my TBI distributor work with the TPI setup?

    any other advise?

    - /forums/images/graemlins/k5.gifchris
  2. 88Silverado

    88Silverado 1/2 ton status

    Mar 13, 2003
    Likes Received:
    Quartz Hill, So. Cal
    I think a TBI is better than a TPI

    Heres a good link with info between the two.
    web page
  3. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
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    Roy WA
    Stay away from the Vortecs. The $400 SDPC base isn't worth the additional expense. Get some good aftermarket heads, (or even some iron or AL L98's) and use the stock base.

    As to cams, first off you are going to want something in the 112* LSA for starters.

    If you want performance out of the setup, I'd check over at There is a bunch of information over there, and quite a few people that have tried to make power with the long runner setup. It can be done, but it's still going to be a tradeoff against the intakes with much shorter runners. (low end torque vs. high end HP)

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