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Thread: Nailhead factory HP/Torque ratings

  1. #1

    Nailhead factory HP/Torque ratings

    I've read a bunch of old threads in this forum and at V8buick.com where alot of you guys have dynoed your engines. My question comes from your HP & torque numbers. My '64 service manual 'claims' 325 HP and 445 torque for a 401 and 340 HP and 465 torque for a 425. Is the factory manual incorrect? If yes, then what was up with that in 1964?

  2. #2
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    I used a HP calculator from another website -inputs are


    weight and 1/4 mile MPH. The #s are from a Car Life article on a '64 Wildcat. Engine was a 2x4 bbl 425. manual trans.


    Inputs:

    Conversions:

    weight = 4420 pound = 4420 pound velocity = 87 mile/hour = 87 mile/hour
    Solution:

    horsepower (hp) = 227.16 horsepower

    Same calculation for a 64 Electra that Car Life tested - it had an automatic.

    Conversions:

    weight = 4265 pound = 4265 pound velocity = 80 mile/hour = 80 mile/hour
    Solution:

    horsepower (hp) = 170.42 horsepower




    So...the marketing guys had more say over the HP listed than the engineers IMHO. They were not alone! All the mfers were pumping up their ##s.
    Last edited by Ted Nagel; 09-19-2010 at 09:39 AM.
    Ted Nagel
    (6)65 Wildcats; 65 Riviera; 65 Special Wagon; 65 GS; 65 Skylark; 67 Wildcat; 67 California GS; (2)68 GS400; 69 GS 350; 70 GS Stage 1; Wanted: time to fix 'em

  3. #3
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    Ted Nagel
    (6)65 Wildcats; 65 Riviera; 65 Special Wagon; 65 GS; 65 Skylark; 67 Wildcat; 67 California GS; (2)68 GS400; 69 GS 350; 70 GS Stage 1; Wanted: time to fix 'em

  4. #4
    Those are ratings at the wheels, correct?

  5. #5
    Ted's conversions would necessarily be "drive wheel horsepower".

    it's important to remember that the 'Gross Horsepower' rating system used up until 1972 didn't even include the transmission, it was taken straight from the flywheel.
    The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
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    H.H. Goddard, Human Efficiency (1920)

  6. #6
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    Also no belt driven accessories and special "Dyno Room" exhaust systems.

  7. #7


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  8. #8
    My results tell me THEY WERE BIG FAT LIARS!

    By my experience on the dyno, there's no way a stock engine can actually achieve the factory rated HP & torque numbers at the flywheel with no accessories and bare stock manifolds.

    I agree that their marketing dept. probably had more to do with the numbers- THEORETICAL NUMBERS that sounded good, and they ran with it. This seems to be a re-occuring theme amogst all the engine manufacturers of the era.a

    Erik
    _________________
    ROA 11755
    65 Riviera GS
    Black/Black (restore in process)
    See dyno break-in run here: http://www.youtube.com/watch?v=xuIKyzct4Sc
    See first dyno pull after overhaul here: http://www.youtube.com/watch?v=TWGYfCwEvO8

    86 LX Police Interceptor (SS) 5.0 Mustang
    (wifes drag car)

  9. #9
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    Yep.
    I think I just bought a stroker kit for a nailhead.
    Have to make another trip to the dyno soon
    Ted Nagel
    (6)65 Wildcats; 65 Riviera; 65 Special Wagon; 65 GS; 65 Skylark; 67 Wildcat; 67 California GS; (2)68 GS400; 69 GS 350; 70 GS Stage 1; Wanted: time to fix 'em

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