Completed the first flight with the "Plastic Plenum" intake manifold.   The
plastic casting took the 1 1/2 hour flight without any obvious signs of
stress.  Temps under the cowling probably hit 220-240F due to high OAT.
This is with the 75mm dia throttle body and larger diameter tubes (1 5/8"
dia secondary and 1 1/2" primary).  Runners are approx 4" shorter than old
manifold.  So it was expected that the torque peak would move up in rpm over
the old intake.  A high density altitude day here with temps in the 90s and
high humidity.

Impressions.  Static rpm was definedly down. Drop from the nominal 5300 rpm
to 5100 rpm (part may be due to high density altitude day compared to normal
operating conditions).  Take off roll was a bit longer which is no surprise.
Seemed to have more torque in the climb as rpm was approx 200 rpm higher at
same climb speed and ROC was approx 100 fpm more.

Top speed increased from my previous max of 196 TAS to 200 TAS at 3000 MSL.
Throttle was more sensitive at lower rpm (like at taxi - perhaps due to
larger throttle body, but could be other factors).  Injectors are now approx
24" further from the intake ports and manifold pressure sensing is taken
right back of throttle plate, so these factors could contribute.

All appears good enough so I can fly to Slobovia Outernational for the
rotary flyin this Saturday.  Will get a better indication with some more
time on it.


Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com