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Thread: L05 to L31 turbo questions

  1. #1
    Carb and Points!
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    L05 to L31 turbo questions

    have a 95 C1500 with L05. I was looking to do a L31 single turbo. any recommendations on efi system, injectors, cam ect. want to try and keep it simple, as close to stock parts as possible and cost affective. I have a complete 98 suburban as a doaner truck. how complicated is it to do a complete L31 swap/conversion. any help would be muck appreciated!!

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    The stock L31 swap shouldn't be too difficult. The problem is getting enough fuel for the turbo. You'll quickly find that the stock injection system is lacking. For a while the cool upgrade was to switch to a marine manifold which used traditional injectors instead of GM's poppet injectors. Sometimes they still show up on Ebay or CL. The Ramjet manifold will also work with the L31 heads although it's expensive. Edelbrock makes a manifold with a short runner length. Part no is 7138. Weiand's 7542P will also fit the L31s. There are "generic" manifolds as well, such as the Hurricane single plane. Many of these manifolds also require a throttle body, fuel rails, regulator, etc to make a complete system. And you might want to ensure any manifold you're considering has a means to provide thermostat bypass as the Vortec blocks aren't drilled for the old smallblock water pump bypass. You'll probably want to swap to an 0411 pcm and maybe use a custom OS if you're going to use a 2 BAR MAP to accurately read pressure for tuning. Make sure you use a fuel pump capable of high pressure as a stock TBI pump doesn't generate more than about 15 psi.

  3. #3
    Carb and Points!
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    thanks for the reply. I have a lot of experience with turbos on imports so the fuel system I have an idea of what I want to use. I wanted to use the L31 block and heads and the TBI off of the L05 but was told this combination is not very tunable. True?

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    Not tuneable??? Maybe that's a matter of opinion?

    The L05 TBI intake manifold won't bolt to the L31 heads. There is an aftermarket manifold but it's not a huge improvement over stock. Many people go with a single plane manifold and an adapter to put the TBI on. If your truck's equipped with an automatic transmission then you should use the 7427 pcm which it likely has now. It's got plenty of parameters to adjust although it isn't scaled for the 2BAR MAP. You'll still need a better pump.

    Just out of curiousity, why TBI?

  5. #5
    Carb and Points!
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    It seems going with TBI would be more bang for the buck. It seems I would have more options going that way VS the L31 spider set up. I do not want to go carb.

  6. #6
    Carb and Points!
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    Got another question. Looked into the dynamic efi but it stills seem to be a piggyback system to maintain control of the tranny. Do any of the other stand alone system (holly, edelbrock, fast) have the capability to piggyback with the stock ECU for tranny control?

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