"Sneed, Glen" wrote:

Anything other than Street Porting, i.e. Bridge Porting/Peripheral Ports,
will be tied to increased exhaust flow/porting and the scavenging cycle of a
tune exhaust header system.  Paul Yaw's excellent white papers on his site
make it very clear.  I am sure everyone who has read Paul Yaw articles will
agree.  It is well worth the time to read them if you are going to take the
step past Street Porting.

Glenn

You must realize that Paul Yaw's experience is heavily weighted towards
automotive use. Surprisingly airplanes with fixed pitch props never 
generate full power at a given RPM until they reach max prop RPM. 
Even at sea level. Unlike a car the continuous load at low RPM's is 
just not there. 

This is a whole new scenario and is best developed on a prop based dyno. 
See the ACRE NL for a sketch of such a device. Variable pitch props are 
only a little different. In that case WOT is not needed below cruise RPM 
and rarely is this max power at that RPM. 

Cars on the other hand need to pull strongly throughout the RPM range.

The bottom line is peripheral ports work fine in aircraft applications.
Allan Tolle has flown a PowerSport peripheral port 13B many times across the U.S.
from California to Florida and then competed in the Sun 100 by going 
238 MPH in an RV4 with a fixed pitch prop no less. The race starts from
a dead stop on the runway. I may be wrong but I think only Dave Anders
has gone faster in an RV4.

Allan also came very close to getting the all time record for time to 
climb from a dead stop on the runway to 3000 feet. With the help of a 
little N.O.. This includes some jets but no turbo props as I recall.

Paul Lamar
 
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