My vote is turbo compound for lower fuel burn.

Paul Lamar

Lower fuel consumption through turbo compound and or other means is a high
priority.

P Port question:

I read the following on http://www.mazdarotary.net/  their description of
the various porting techniques to increase Hp advantages and disadvantages.

Peripheral Port

"The peripheral port is the ultimate form of porting for a rotary engine
without turning to forced induction. Instead of conventional metal shaping
with a grinder, the side ports are actually filled and completely new
circular - peripheral - intake ports are fitted directly through the rotor
housing and is easily identified on an engine by its tubular intake
manifold. This modification has potential for over 300hp but as it is
developed for racing, results in very poor drivability, fuel consumption and
needs an exhaust system designed to produce excessive noise. Like the bridge
port, the PP produces its maximum power past 8,000rpm creating increased
stress and wear on components.

And instead of idling at around 1,000 - 1,500rpm for the previous porting
methods, the PP engine will not idle much below 2,000rpm and is impractical
and virtually unusable on the street.

PRO'S: The ultimate form of rotary porting for maximum power
CON'S: Excessive noise, extensive intake mods, very poor drivability and
fuel consumption, relatively short engine life, very expensive, narrow power
band."

As our interest is in higher power to weight ratio engines for special
mission flying - about 85% constant high power settings - how much of the
above is true and or a real problem.

Is P porting say a 13B or RX8 engine expensive to do?


Cheers,
Brian

Not true on the P-port. An RX8 p-port intake  with a side exhaust port is no
worse than a 3rd gen side intake with p-port exhaust. Same O same O. The RX8
P-port has more power as it is more important to help the intake breathing than
the exhaust breathing.

http://www.youtube.com/watch?v=LkKw72dZ2yc
This video shows how cheap and easy it is to do.

P-ports in all cases reduce fuel consumption in our power range from 5000 RPM on
up. The Le Mans winning p-port engine had a fuel limit. It would not be able to
win the race if the p-port consumed excess fuel. Too many pit stops and or it
would run out of fuel. Lower pumping losses is the reason. For aircraft use
using a 2.85:1 gear box you don't need to idle below 2000 RPM anyway.

http://www.rotaryeng.net/Mazda_R26B_US.pdf

Paul Lamar

Paul and Brian,
This same old claim of reduced engine life from a PP annoys the hell out of
me. For sure the engine life is reduced when running any engine at maximum
RPM and sure the PP allows the motor to run at much higher RPM's and
produces much more HP - as in racing and drag racing.

HOWEVER, for aviation use at mostly 6,000 rpm we are not flogging the engine
in any way, we are merely allowing the engine to breathe effectively to
produce max VE (volume efficiency). For the life of me can't see how that
reduces engine life - in fact there are less stresses on the engine than
when a turbo is used to produce the same amount of HP.
George (down under)

Well said George.

Paul Lamar