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Thread: L30 / L31 "base engine friction torque vs rpm vs vacuum" table

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  1. #1
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    L30 / L31 "base engine friction torque vs rpm vs vacuum" table

    Does anyone know how GM populated this table? It seems like the L30 and L31 tables should have some type of relationship that's easy to see. Base engine friction seems like it's going to be affected by stroke and bore more than anything else. The L30 and L31 are very similar, with the only major difference being the bore and possibly a slightly smaller cam on the L30. Yet comparing this table between the two engines shows some unexpected differences. Has anyone played with this or maybe heard something about how the tables were developed? Any theories???

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    Quote Originally Posted by 1project2many View Post
    Does anyone know how GM populated this table? It seems like the L30 and L31 tables should have some type of relationship that's easy to see. Base engine friction seems like it's going to be affected by stroke and bore more than anything else. The L30 and L31 are very similar, with the only major difference being the bore and possibly a slightly smaller cam on the L30. Yet comparing this table between the two engines shows some unexpected differences. Has anyone played with this or maybe heard something about how the tables were developed? Any theories???
    L30 and L31 use teh same 191/196º .412".428" 111ºLSA cam. Same cam used in the 1994-96 Impala SS/Caprice/Roadmaster/Cadillac GEN 2 5.7's with iron heads as well as the 94-96 GEN 2 4.3 V8(VEE eight) Caprice engine(200hp). That cam was pretty popular.

    Between the L30 and L31, I'd think the L31 would have slightly more friction due to the greater ring/bore contact vs. the smaller bore L30, but who knows.

    So I looked it up, here you go.

    Vortec 350 L31
    0-400-800-1200-1600-2000-2400-2800-3200-3600-4000-4400-4800-5200-5600 rpm
    14.00 17.00 20.30 23.70 26.59 31.00 38.41 45.91 54.00 61.30 68.59 75.09 82.00 89.00 96.00 0kpa
    17.16 20.92 25.09 28.09 29.92 34.08 41.31 49.89 57.72 62.27 69.67 75.05 80.61 87.59 94.55 20kpa
    19.83 24.77 30.52 33.13 33.44 36.64 43.61 52.70 61.23 63.66 70.48 75.20 79.92 84.77 91.64 40kpa
    23.33 30.36 34.78 37.27 36.86 39.05 45.56 55.08 62.70 65.13 70.78 74.09 77.83 81.94 87.27 60kpa
    26.83 32.67 39.13 41.44 40.19 41.19 47.03 55.91 61.98 64.39 69.31 71.16 75.05 79.11 84.36 80kpa
    29.17 35.63 42.25 43.91 41.80 41.69 47.31 55.16 61.39 63.08 65.44 69.50 73.66 77.70 82.91100kpa

    Vortec 305 L30
    15.92 16.92 18.11 21.36 26.09 30.70 35.25 40.69 47.50 55.28 62.39 69.86 77.03 84.00 91.00
    19.77 20.77 22.13 25.00 29.42 33.78 38.09 42.53 48.73 56.27 63.20 69.56 76.94 83.80 90.41
    23.39 24.39 25.86 28.72 32.75 36.70 41.50 44.94 49.95 57.23 64.16 69.73 77.42 83.00 89.50
    27.47 28.47 29.53 31.98 35.88 39.34 44.44 47.47 51.31 58.08 65.42 69.55 76.52 80.00 87.00
    30.63 31.63 32.91 34.97 38.56 41.52 46.09 49.17 51.70 58.28 64.25 68.75 72.70 77.00 82.00
    33.59 34.59 35.91 37.70 41.09 43.50 47.59 50.70 52.09 58.41 63.80 68.00 70.00 73.00 76.00

    Vortec 454 L29
    22.39 27.09 31.88 34.67 40.72 48.83 59.95 75.03 90.53 104.47 114.80 121.06 125.23 131.30 136.55
    27.98 31.44 35.17 37.11 43.08 50.36 60.77 75.53 89.91 104.05 114.48 120.72 124.75 130.83 135.16
    39.19 42.92 44.77 43.95 49.23 55.50 63.86 77.08 89.91 103.20 113.75 119.70 123.77 128.45 131.91
    48.14 49.86 51.16 50.30 56.42 61.67 67.98 79.14 89.91 102.16 112.19 117.97 121.33 124.64 127.27
    54.86 55.92 56.48 55.09 64.63 68.88 72.09 81.70 89.81 99.42 107.92 112.89 114.48 118.94 120.77
    52.63 53.11 54.36 50.80 54.36 60.64 74.16 79.14 87.33 93.11 99.14 102.72 106.66 107.52 111.47

    peace
    PAuly

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    Quote Originally Posted by Hog View Post
    L30 and L31 use teh same 191/196º .412".428" 111ºLSA cam. Same cam used in the 1994-96 Impala SS/Caprice/Roadmaster/Cadillac GEN 2 5.7's with iron heads as well as the 94-96 GEN 2 4.3 V8(VEE eight) Caprice engine(200hp). That cam was pretty popular.

    Between the L30 and L31, I'd think the L31 would have slightly more friction due to the greater ring/bore contact vs. the smaller bore L30, but who knows.

    So I looked it up, here you go.

    Vortec 350 L31
    0-400-800-1200-1600-2000-2400-2800-3200-3600-4000-4400-4800-5200-5600 rpm
    14.00 17.00 20.30 23.70 26.59 31.00 38.41 45.91 54.00 61.30 68.59 75.09 82.00 89.00 96.00 0kpa
    17.16 20.92 25.09 28.09 29.92 34.08 41.31 49.89 57.72 62.27 69.67 75.05 80.61 87.59 94.55 20kpa
    19.83 24.77 30.52 33.13 33.44 36.64 43.61 52.70 61.23 63.66 70.48 75.20 79.92 84.77 91.64 40kpa
    23.33 30.36 34.78 37.27 36.86 39.05 45.56 55.08 62.70 65.13 70.78 74.09 77.83 81.94 87.27 60kpa
    26.83 32.67 39.13 41.44 40.19 41.19 47.03 55.91 61.98 64.39 69.31 71.16 75.05 79.11 84.36 80kpa
    29.17 35.63 42.25 43.91 41.80 41.69 47.31 55.16 61.39 63.08 65.44 69.50 73.66 77.70 82.91100kpa

    Vortec 305 L30
    15.92 16.92 18.11 21.36 26.09 30.70 35.25 40.69 47.50 55.28 62.39 69.86 77.03 84.00 91.00
    19.77 20.77 22.13 25.00 29.42 33.78 38.09 42.53 48.73 56.27 63.20 69.56 76.94 83.80 90.41
    23.39 24.39 25.86 28.72 32.75 36.70 41.50 44.94 49.95 57.23 64.16 69.73 77.42 83.00 89.50
    27.47 28.47 29.53 31.98 35.88 39.34 44.44 47.47 51.31 58.08 65.42 69.55 76.52 80.00 87.00
    30.63 31.63 32.91 34.97 38.56 41.52 46.09 49.17 51.70 58.28 64.25 68.75 72.70 77.00 82.00
    33.59 34.59 35.91 37.70 41.09 43.50 47.59 50.70 52.09 58.41 63.80 68.00 70.00 73.00 76.00

    Vortec 454 L29
    22.39 27.09 31.88 34.67 40.72 48.83 59.95 75.03 90.53 104.47 114.80 121.06 125.23 131.30 136.55
    27.98 31.44 35.17 37.11 43.08 50.36 60.77 75.53 89.91 104.05 114.48 120.72 124.75 130.83 135.16
    39.19 42.92 44.77 43.95 49.23 55.50 63.86 77.08 89.91 103.20 113.75 119.70 123.77 128.45 131.91
    48.14 49.86 51.16 50.30 56.42 61.67 67.98 79.14 89.91 102.16 112.19 117.97 121.33 124.64 127.27
    54.86 55.92 56.48 55.09 64.63 68.88 72.09 81.70 89.81 99.42 107.92 112.89 114.48 118.94 120.77
    52.63 53.11 54.36 50.80 54.36 60.64 74.16 79.14 87.33 93.11 99.14 102.72 106.66 107.52 111.47

    peace
    PAuly
    As piston surface area increases so do the pumping losses. These losses become higher and higher as the vacuum increases and the piston has to fight increased resistance.

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    So I looked it up, here you go.
    Thanks.
    Those tables match the ones I have here. I wonder if they're consistent across all L30 / 31 equipped trucks.

    As piston surface area increases so do the pumping losses. These losses become higher and higher as the vacuum increases and the piston has to fight increased resistance.
    Agreed. With so many similarities between engines it should be fairly easy to see this occurring by comparing tables but the comparison tells a different tale:

    Vortec_Friction_Torque.jpg

  5. #5
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    An L31 should be similar to an LT1, but I cant find those tables in any LT1 calibration.

    peace
    Hog

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    I expect they're part of the torque calculation for torque management. I don't remember seeing engine torque as an active variable in the LT1 calibrations. It may be part of the 4.3 calibrations so I'll check a few of them out.

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