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Thread: True Horsepower

  1. #1
    Administrator Ron77's Avatar
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    1969 NASCAR Cobra, 428SCJ engine bored .065 and sonic tested and balanced and blue printed.

    True Horsepower



    Ron
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  2. #2
    Senior Member DanEC's Avatar
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    ERA Street Roadster with 459 KC FE motor, toploader
    If these video producers are going to discuss Detroit under-rating, I don't know why they throw in all this video of obviously modified to highly modified engines. That first 440 Purple Challenger was ridiculously cammed or badly needed to adjust his choke for a cold morning start.

    Probably disagree on the inclusion of the 440-4bbl. Not even the Mopar guys consider it under-rated. Just the opposite actually. A few others they could have included - Boss 302, Mopar 340, Z-28, Olds 455 W-30, Pontiac Ram Air IV.
    I was deplorable before deplorable was cool.

  3. #3
    Administrator Ron77's Avatar
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    1969 NASCAR Cobra, 428SCJ engine bored .065 and sonic tested and balanced and blue printed.
    Dan,

    I don't know about all of those but my 428SCJ "R" code engine I had dynoed and it put out 440 horse instead of the advertised 335. And I know that bumped those engines up into the 400 plus range at the drag strips. The only "Q" code 428CJ that I saw dynoed was 412 horse.

    Ron
    Last edited by Ron77; 01-14-2018 at 03:22 PM.
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  4. #4
    Senior Member DanEC's Avatar
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    Ron - yes, the 428 CJ was definitely under-rated in all versions. Not sure how Ford kept a straight face considering the 390 GT was rated at 335 HP just a year or two before.
    I was deplorable before deplorable was cool.

  5. #5
    GROUCHY FUC***G OLD APE Silverback's Avatar
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    The same way that GM did when they rated the L-88 at 430HP.

  6. #6
    Senior Member DanEC's Avatar
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    ERA Street Roadster with 459 KC FE motor, toploader
    just an opinion but I think the 428 CJ may have been even more underrated than the L88. From talking to Keith Craft's dyno guy, a couple of magazine engine resto dyno tests and input from others like Ron, it looks like a standard 428 CJ usually put out about 410 HP with factory exhaust manifolds. The "R" CJ like Ron has - is such a rare bird I'm not sure anyone really knows. Ron's dyno experience is problaby as definitive as we would find - assuming it was with factory manifolds.

    The L88 was rated at 5200 rpm for 430 HP - way below peak rpm which was a favorite trick of Chev. But it's breathing was really restricted by the factory exhaust manifolds. Here is an interesting post by a fellow who reasonably tried to re-create his L88 in factory tune and dyno with stock manifolds and then headers.

    https://www.corvetteforum.com/forums...y-headers.html
    I was deplorable before deplorable was cool.

  7. #7
    Administrator Ron77's Avatar
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    1969 NASCAR Cobra, 428SCJ engine bored .065 and sonic tested and balanced and blue printed.
    Dan,

    Mine was done with the factory manifolds which are still on it. They wanted to put headers on it but I wouldn't agree to that as I wanted the power as it was going to be driven. The dyno guys claimed, not substantiated, that headers would have added at least another 25/40 horsepower. But I wasn't going to have the shock towers cut up in order to put headers on it when it was in the car.

    Ron
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