Don Dunbar, Dave Mccandless and I took a close look at this Revmaster carb for
use with rotary, One would need two to get over 200 HP.
This looks like a good low cost and simple solution for the fuel system.
It appears to be a Mikuni flat slide carb of some kind with the float
bowl removed. However I cannot find the exact Mikuni model or on what vehicle
it was used. I suspect the float bowl is removed to allow the mixture
to be adjusted using a low pressure gravity fuel feed. Rather brilliant
idea on Joe Horvath's parts. Joe is charging $330 each so I'll bet the
original version with float bowl is a lot cheaper.
Any body recognize this carb body?
Paul Lamar
It looks like a variation of a quicksilver carb.
http://www.edelbrock.com/motorcycle/carbs/carb_internals.pdf
http://www.edelbrock.com/motorcycle/carbs/intro.shtml
Jim Pollard
Yes. They are for a whole wide range of off road vehicles.
They all seem to have about a 40 mm bore in common.
Therefore they are limited to about 40 to 50 HP per carb.
On second thought not a good solution for a rotary.
You need at least two 48 to 50 mm bore carbs for a p-port rotary.
That gets us back to the Big Mikuni size carbs.
Now you must figure out a way to lean them at altitude.
Not easy. I think the float bowl is already pressurized
by dynamic pressure.
Paul Lamar
Paul,
Have you considered a siamesed intake with staged carbs for the P-port. A
couple of staged 36mm would do the job giving higher inlet velocity and calm
the idle. Or perhaps two different sized carbs, say a 32mm ( 1 1/4") primary
and a 40mm ( 1 1/2") secondary, same as the original Mazda carbs.
The siamesed inlet could be joined horizontally rather than vertically,
further enhancing idle.
George (down under)
Higher inlet velocity increases the skin friction drag inside
the intake manifold which is the exact opposite of what you want.
Skin friction drag is proportional to the velocity squared.
What you want is the largest diameter tuned pipe you can get
to obtain the most HP at the high RPM range we need for aircraft.
Mazda showed the way with the LeMans engine. Why not just copy
that? Nobody has obtained more power from a normally aspirated
rotary engine than Mazda.
A smooth idle is of absolutely of no consequence in an aircraft
engine. Would you say my 470 cubic inch 230 HP Continental engine
in my Cessna 182 was idling smoothly? I would say not because it does
not need to.
This high inlet velocity crap is coming from people that want
low RPM torque for cars. Airplanes fly on HP and not torque.
It would not surprise me one bit if Mazda used a trap door P-port on
the street RX8 engine any day now. Along with a double clutch transmission
it would be better than a 16B and a lot more fun to drive.
http://www.rotaryeng.net/RX8-p-port.html
Paul Lamar
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