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Thread: TBI 5.7 to LS1 5.7

  1. #1
    Join Date
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    TBI 5.7 to LS1 5.7

    I've got a 90' K1500 with the old TBI 350 in it, and my brother has a 5.7 out of a '98 Corvette, can anyone tell me how hard the conversion is?

  2. #2
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    Nov 2003
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    Here is a topic that is close to what you're wanting to do. http://www.ls1truck.com/forums/lsx-t...onversion.html

    Its not too bad, just time consuming and will empty your penny bank. You will need electric fans for the LS1 conversion, also.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  3. #3
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    i know the 97-98 had perimeter valve covers but was the performance different? I had two 98 fbody engines and they ran good, not as good as my 408 but still ran really good.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  4. #4
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    Nov 2008
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    Southern Minnesota
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    So in theory i can use my 700R4 tranny and factory motor mounts, but i will need radiator, electric fan, computer and wiring. I don't anything about the newer
    V8's so correct me if i'm wrong. Another question is would it be more financially feasible to build the motor i have, or should i go for the LS1?

  5. #5
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    Use the OBS Gen1 V8 motor mounts with adapter plates. You'll spend twice as much money on a TBI engine trying to match the same amount of power you'll get right out of the box with an LS1. I would also recommend that you get a wiring harness and PCM from a 99-2002 vehicle. I've done this twice now with 98 engines and everything just plugs right in. The 98 harness is wired all goofy-footed and will not work with a 99-2002 PCM
    Last edited by RedHeartbeat; 11-06-2008 at 07:32 AM.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  6. #6
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    You can change a few of the pins around and the '98 harness will work with the newer PCM.

  7. #7
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    yes you can and its not just a few, its a whole lot of them. When you're done you have a nasty spaghetti looking mess.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  8. #8
    Join Date
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    Sellersburg, IN
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    Quote Originally Posted by RedHeartbeat View Post
    yes you can and its not just a few, its a whole lot of them. When you're done you have a nasty spaghetti looking mess.
    It's been awhile since I have done one, but now that you mention it I think there was quite a few that had to be changed.

    Offtopic: Do you have any pics of your truck with the C5 wagon wheels?

  9. #9
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    current truck




    previous truck
    Last edited by RedHeartbeat; 11-09-2008 at 11:36 AM.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

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