bit of confusion on exhausts

[rapieper@yahoo.com (Ron Pieper)]

--- Rick Alexander <ralexander03@snet.net> wrote:
> Back pressure is no myth. Backpressure is required and even
> calculated by
> the engine designers to prevent the raw fuel charge from flowing
> right
> through the engine without going through the compression cycle. 

Well, I haven't book-studied this yet but have experienced it
first-hand.  As a kid on my Honda CT70, I tried removing the baffle in
the exhaust.  I went down the street and noticed my top speed had
dropped (to 28mph IIRC - fast).  I reached back and put my hand over
the exhaust and the minibike went faster - back to it's max. 32 or so. 
A definite difference.

I'm going to offer a low-risk guess that there's a fine relationship
between exhaust gas velocity (and its scavenging affects) and
restriction/backpressure for the effect Rick noted above.

Sheesh - now I have to go buy more books...

=====
Cheapass Ron
'87 Scirocco 16'Victor'

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