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  1. #1
    I'm Awesome 1BadBowtie's Avatar
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    Default L31 R Horsepower and Torque Ratings

    I have just put in a L31 r crate motor to replace my blown up 350 in my 98 Sierra. It is made as a direct replacement. My question is does anyone have a sheet on the ratings for this motor? I read in another forum when they started making these motors they where rated as a replacement with 330 hp but i dont think this is right! when the old one was at 255 hp. Any info would help thanks


    Dan

  2. #2
    Hired Goon Aloicious's Avatar
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    255hp, 330 tq is stock, I would suspect your crate is the same
    '96 C1500 ECSB, 5.7L the "LS31", T56, 411 PCM, EFILive self-tuned, LC-1, Distributorless 24x CNP, LS2 coils, ZZ4 cam, Custom MPFI, RHS heads,
    Hydroboost, LT's/dual 3", Mark VIII Fan, Truetrac, 4.88, sound deadened, DEH-P600UB, Polk comps/10", kicker amps. COMING SOON: Twin Turbos...

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    Newbie asolek88's Avatar
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    The Vortec 5700 produces 255 hp (190 kW) to 350 hp (261 kW) at 4600 rpm and 330 lbft (447 Nm) to 350 lbft (475 Nm) of torque at 2800 rpm. Thats from Wikipedia, So I guess they rate them 225-350 I sure hope I have a 350hp one
    1996 silverado C1500 L31

    Vortech V1 supercharger, Marine intake, 48lbs Injectors, Hooker super comps, MSD ignition, Walbro 255, TCI overhaul kit, TCI breakaway converter, Richmond 4.10's, Detroit trutrac, Drilled and slotted rotors

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    Hired Goon Aloicious's Avatar
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    this is an old thread, but I've never heard of a 350hp factory L31. unless they're refering to some special crate or replacement motor or police edition or something, I would question their data. all factory L31's that I'm aware of from 1996-2001 were rated at 255hp/330ftlbs.
    '96 C1500 ECSB, 5.7L the "LS31", T56, 411 PCM, EFILive self-tuned, LC-1, Distributorless 24x CNP, LS2 coils, ZZ4 cam, Custom MPFI, RHS heads,
    Hydroboost, LT's/dual 3", Mark VIII Fan, Truetrac, 4.88, sound deadened, DEH-P600UB, Polk comps/10", kicker amps. COMING SOON: Twin Turbos...

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    Newbie asolek88's Avatar
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    So a L31 rated at 255 with spider injection.... A L31 with marine intake.....what kind of HP could you see?
    1996 silverado C1500 L31

    Vortech V1 supercharger, Marine intake, 48lbs Injectors, Hooker super comps, MSD ignition, Walbro 255, TCI overhaul kit, TCI breakaway converter, Richmond 4.10's, Detroit trutrac, Drilled and slotted rotors

  6. #6
    Hired Goon Aloicious's Avatar
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    well, a factory stock L31 is rated at 255hp, the spider injection will fuel a little bit more without too much difficulty....but a marine isn't factory, the benefit of a marine is the ability to fuel more power correctly. so you might gain a little power from the intake swap alone, but once you start modifying the engine further and further, thats when the marine (or other external MPFI) will really shine.
    '96 C1500 ECSB, 5.7L the "LS31", T56, 411 PCM, EFILive self-tuned, LC-1, Distributorless 24x CNP, LS2 coils, ZZ4 cam, Custom MPFI, RHS heads,
    Hydroboost, LT's/dual 3", Mark VIII Fan, Truetrac, 4.88, sound deadened, DEH-P600UB, Polk comps/10", kicker amps. COMING SOON: Twin Turbos...

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    I'm Awesome heavychevy98's Avatar
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    mastercraft mcx vortec is 350hp/380ft.lbs whole differnt ball game tho. . .

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