True 426 Street Hemi Horsepower

Discussion in 'First Generation Challenger Forum' started by SRT-Tom, Jul 27, 2019.

  1. SRT-Tom

    SRT-Tom Well-Known Member Staff Member Super Moderator Article Writer

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    The July 2019 issue of Hemmings' Muscle Machines magazine had an interesting article about the 426 Street Hemi's true horsepower. Officially, it was rated at 425 hp.@5,000 rpm. However, just like the high-revving 340 engine that was under-rated at 275 hp.@5,000, the Hemi did not make its peak horsepower until 6,000 rpm.

    The article cites a freshly built 1966 Street Hemi that cranked out 459 hp.@5,000 rpm and 494 hp. at 5,900 rpm with stock exhaust manifolds and no air cleaner. The engine had solid lifters, an electric water pump, electronic ignition and a .25 increase in compression.

    In a dyno test of another correctly restored Hemi, the engine made 425 hp.@5,000 rpm (the factory's advertised number) and 500 hp.@6,000 rpm.
     
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  2. 70-426_10-SRT

    70-426_10-SRT B&E body lover

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    Add a roller Crower Cam, bigger Carbs and a little Head Work
    And those things CAME ALIVE
    And I can attest to the 5-7k pull
    I still set the Shift Light at 5500 as it was my daily driver too.

    I really miss the sound :(
     
  3. ZEN357

    ZEN357 Full Access Member

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    I would definitely go Roller Cam and Roller Rockers if building one today.