How much real power?
Although rated at 430 horsepower by the
old method, Chevrolet never released actual power figures
for the as-installed production ZL-1 engine. Numbers were
tossed around for years until Bill Porterfield decided to
find out. Bill had acquired an original block from one of
the cars and enough NOS parts to complete another engine.
The engine was subjected to 5 levels of test. RPM was
limited to 6750.
Engine Test
Configuration Result
---------------------------- --------
All accessories, production 375.7 HP
exhaust manifolds, Camaro
chambered exhaust system,
36 degrees timing
As above with 2-1/8" headers 418.9 HP
replacing the manifolds
Air cleaner, alternator, AIR 447.2 HP
pump removed
Carb re-jetted, timing set 444.2 HP
to 39 degrees
Chambered exhaust system 523.6 HP
removed
The ZL-1 was a legitimate 500+ horsepower engine.
Others have recently built ZL-1's with similiar or higher results.
Several have dynoed in the 540-550 HP range. Modern components like
piston rings may be the cause of the slightly higher performance.
