Paul and all, what are the draw backs of a throttle body located on
the far end of wrap-over  intake pipes (like Power Sport)?
Another thing, what about both pipes getting air from one plenum with
single large throttle body?
Bulent "Buly" Aliev
FXE Ft lauderdale, FL
 http://tinyurl.com/dcy36

The power sport throttles are right in the rotor housings.
Is that what you mean? the reason they are there is to cut
down on the stored exhaust gas in the intake runner.

In a p-port engine at low RPM the exhaust gas is
of higher pressure than the air in the intake runners. Some exhaust gas
is therefore transfered to the intake runners past the rotor depression.
This is contaminated gas CO2 CO NO  and it mixes with fresh air
and is taken into the engine. This causes the p-port engine to
misfire periodically and leads to rough running. The same effect is
noticed in a side port engine with a p-port exhaust but to a
lesser extent. This is why your engine misfires every now and
then especially when you are on short final and the airplane
is driving the prop and engine. As much as 10 times a minute.
A conventional p-port engine might misfire half the time. The
whole reason they built the side exhaust port RX8 engine was to
further minimize this effect because it causes high hydro carbon
emissions every time it misfires.

Placing the throttle close to the rotor housings on the p-port
engine reduces this effect as less exhaust gas is stored.
This is nothing new. The p-port NSU Wankel Spyder had this
feature in 1965 or there abouts.

The draw back to any butterfly in the intake runner
is; it cuts down on the amount of air getting in the
engine and therefore the amount of power generated.
It also causes a slight increase in pumping losses
which increases the fuel burn slightly for a given
power level.

That is why slide throttles are used on high power
rotary engine as well as a lot of piston engines.
Mazda wanted to get the best BSFC possible for
the Lemans engine because the rules specified
a maximum of fuel that could be burned during
the race. That is one reason the Lemans engine
had p-ports. The BSFC was better than anything
we have seen so far with side ports.

To answer your question... yes a butterfly will work
located in the plenum but the p-port engine will
idle like crap :)

Paul Lamar ...No rotor no motor.

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