RE: [theory] Exhaust size/restriction vs. power

["Scott F. Williams" <sfwilliams@home.com>]

> OK, Scott. Normally I have completely blind faith in your words
> of wisdom,

Uh oh! Now, we're really in trouble! :^)

> but you just said one thing and then (on face value) *completely*
> negated your first statement.

Yah, I could have communicated that much better. -damned sales meetings
getting in the way of articulating my engine tuning thoughts... Um, what I
mean is that gas back pressure in and of itself does not contribute to
making more power. It is simply a function of a particular exhaust design.
Generally, the smaller exhaust will flow faster at low rpms. This promotes
better evacuation of the exhaust from the combustion chamber.

Think of it this way, if you take your favorite Techtonics exhaust and block
half the flow with a banana, chances are good that you will increase the
back pressure in the system. Will the power increase? No, of course not. If,
however, you could maintain the same exhaust flow (or actually increase it)
while eliminating all back pressure, would you make more power? YES!

As I mentioned in another recent email, tuning the exhaust's acoustics will
also affect the powerband. The goal here is to tune the pipe diameter,
bends, and arrangement to send a shock wave back to the combustion chamber
that forces any unburned fuel and air back into the cylinder.

Sorry for the miscommunication.
--
Scott F. Williams
NJ Scirocco nut
Golf GTI 16v rallycar
Mazda 323 GTX turbo assault vehicle

Check out our rally team's website!
http://www.usrallyteam.com


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