> Am I wrong or is quite easy to subtract horsepower from a motor
by hand porting and polishing? What if you take too much off?
I was talking to CNC and they told me that alot of the polishing
is cosmetics only.Personally, I think I'll leave it to someone
witha flowbench.
Generally speaking, if you are conservative with your porting work, you
will *usually* gain some flow. You can do damage, though. You can
almost NEVER go wrong with smoothing out rough edges. Depending on where
the big restriction in the total flow through the engine is, you may or
may not gain HP by opening up the TB.
I own a 95 Impala SS. One of the big mods is a bigger TB. Dyno tests
have shown that going from the stock 48mm to the bigger 52mm TB is only
worth about 1 hp on an engine with bolt on mods. The honkin' 58mm unit
will usually result in low-end HP and torque loss with the engine not
getting into the rev band where this TB will work. Swap out heads, add a
cam or some sort of compressor, the whole picture changes.
The only way to tell for sure though, is to do back-to-back dyno tests,
and try to keep the atmospheric conditions as close to the same as
possible.
As for polishing, if the TB is flowing air and fuel, don't polish it. If
it is passing only air, there will be some minor gain by polishing it (it
reduces the turbulence against the wall of the TB).
Gene Beaird
Dakota-less, but looking for a R/T
Houston, Texas
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