Brian writes:
> Cold air makes horse power- ask any hot rodder.
Agreed. But pure hot rods don't work well as street cars.
> ...from my rather limited experience and what I have learned from others,
> manifold preheaters are not a good thing if you want to maximize power
> output.
(Boy, am I gonna get flamed... Disclaimer: I'm not a professional engine
builder!)
Perhaps if you want to maximize power output under a narrow band of
ideal conditions. For daily street use, consistency is required if you
want the tune to work all the time. And stabilizing the manifold temp
helps obtain this.
Not only do you need fuel in the engine, it needs to be completely
atomized and mixed thoroughly with the air. On a cold manifold, the
fuel vapor will condense on the walls. Puddles of raw gas don't make
for smooth power :-)
As for smog, why then do pre-smog early '60s muscle cars have
internal preheat passages in their cast iron behemoth V-8 manifolds?
And why do they run poorly when those passages get clogged up
with carbon deposits (exhaust gas is the heat source)?
Now, fuel injection changes the rules, where the fuel is atomized by the
injector. So let's limit the conditions of this discussion to carbureted
induction.
-- John
John F Sandhoff sandhoff@csus.edu Sacramento, CA
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