Jerry Hey wrote:

Paul,  on your drawing of the pp modification you have the
instruction to "Port the Inner Part with a die grinder to square it
up,"   what are your referring to?  Does the port transition from
round on the  outside to square on the inside?

Yes. Here is a picture of a racing beat PP.
The drawing is of Ken Powell'e variable timing PP but
it shows the dimensions of the square. You should round off
the corners.

Can you provide a drawing showing the inner
shape?   Also, is there a throttle body available as you have drawn
it, or one  that can be modified?   Jerry

You will have to make that part. Two throttle bodies are used. One for
each rotor housing. Gives a better idle when the butterflies are close
to the rotor housing.

Paul Lamar

Paul and Jerry,
   I would love to see the variable PP design installed and tested.  
Jerry, would you
be interested in installing the variable PP intake valves that Paul 
built?  I would be
happy to send them to you if you are interested.
   It is thought by some that a PP motor with large amounts of overlap 
has
somewhat poor idle characteristics due to exhaust gas dilution of the 
intake charge.
In order to minimize this intake charge dilution we decided to use the 
same
technique that are used on 2-stroke racing motorcycles, i.e., vary the 
port timing on
the intake port.  A secondary benefit is that at small throttle 
settings the velocity of
the intake charge is accelerated while in the intake port, further 
promoting fuel
atomization.  Also note that the BSFC should improve at cruise due to 
the more
conservative port settings.
   A slower idle is important because even at 700 - 800 prop rpm a 
highly pitched
prop will generate lots of thrust.  Since the Fast Glass and the RV's 
are difficult to
slow down a slower prop speed is beneficial.  Note that a 1200 rpm 
idle (engine)
when used with a 2.85 redrive will result in a prop rpm of only 421 
rpm, a
substancial reduction over a 1800 rpm idle and a 2.17 redrive wich 
results in a prop
rpm of 830 rpm.

Ken Powell

Ken I am interested and I would like to have the variable intake 
valves.  However, I need to say that it would be some time in the  not 
near future before I could install them.  First, I will try to build a 
simple PP port and see how that goes.   Jerry

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