The maximum horsepower on this dyno run was 433.5 hp (that's 463 corrected horsepower), 405 lb-ft of torque at 6,000 rpm. Max torque was 472 lb-ft at 4,000 rpm with 336 lbs of load (also max load; corrected). So when did it reach 425 horsepower, its rated level? If you use the corrected figures, it had passed 425 horses at 5,200 rpm.
This is not necessarily a test from a production engine. Our source wrote: “The dyno tests were conducted in cells 12 and 13 of Building 135 in the old Highland Park complex.” The test sheets were found nearby, apparently discarded.
413 Long Ram Dyno Test Sheet
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