Here is an interesting article from 1968, it came from Chevrolet Engineering
and was published in How to hot rod big block chevys. The dyno sheet states:
Gross Power VS Bore/Stroke.
Comparison of
392 CID engine 4.25 X 3.46
396 CID engine 4.09 X 3.76
Both engines had mechanical lifter cams with 0.560/0.540 inch exhaust / intake
lift. Intake valves were 2.19 inch diameter and exhausts were 1.84 inch. The
392 CID engine had 11.3-1 compression ratio and 34 inch long exhaust pipes into
a collector. The 396 CID engine had 12.1-1 compression ratio and 36 inch pipes
into a collector. One 850 CFM Holley 4 bbl. was used with air cleaner base
only. Friction torque obtained by motoring the engine. NOTE the lower friction
torque and higher outputs obtained with the shorter stroke engine, even with
lower compression ratio.
HP @ 7000 RPM
392CID = 560HP
396CID = 540HP
Torque @ 6000 RPM
392CID = 460 Lbs. Ft.
396CID = 440 Lbs. Ft.
Friction torque @ 6000 RPM
392CID = 114 Lbs. Ft.
396CID = 130 Lbs. Ft.
" Although the shorter stroke gave slightly more power and even a bit more
torque above 3000 RPM, it was a dirty engine from an emissions standpoint. So
the longer stroke 454 became the Mr. Clean replacement and we were all treated
to the availability of a stock 4 inch stroke crank from the dealers."
More food for thought. Regards, Tom
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