Paul,

Is the optimum length for the intake runner on a 13B 2nd gen P Port 27"
for optimum power at 6500 to 7000 RPM?  Is this measured from the
chamber outward?  I have a space issue and will have to snake one of the
tubes a little.

Joe Berki
Limo EZ

Chamber outward.
That is about right. 25 to 28 inches. I would make it ground adjustable
so you can tune it after you get your prop. You can tune it for lowest
fuel burn at the cruise RPM you chose or for max power at takeoff and climb out speed.
If you have a 2.85:1 gear box you can use 7500 RPM for take off and climb out.
You will also need a plenum and ram air scoop on the end to contain the fuel mist.

Come out straight as far as you can before you go up and over.