X-Mozilla-Keys:                                                                                 
Gary Wolf wrote:

   I am building a Pegazair STOL which was designed around the 85-100 hp
Continentals. Weight is very important on this plane to retain the low
landing speed. I had been planning on using a turbo EA81 Subaru as on my
Dragonfly, but I am curious about the Mazdas.
   What would be the recommended combination to replace the 100 Continental
and what would the fuel burn be?

                                                Gary Wolf

With a two rotor and PSRU  the weight would be over that of a O-200
Continental.

A one rotor turbo or peripheral port you could easily get the same 100
HP with the same weight. If you run the Continental at 50 or 100 degress
lean of
peak and you use an EFI on the one rotor you would be looking at
roughly the same fuel burn. If you went with Klaus's electronic
ignition on the O-200 you could easily beat the rotary on fuel burn
despite running rich of peak.

If you are brave and meticulous you could also beat the fuel
burn on the rotary by about 15 to 20% by leaning the O-200 to
50 degrees lean of peak EGT. Be sitting down if you burn an 
exhaust valve however.

100 HP is about 75 HP cruise at .5 pounds of fuel per HP hour we are
talking about  6.25 gallons per hour verses 5 gallons
per hour running the O-200 lean of peak. Given the cost of 
the O-200 it would probably take quite awhile with fuel at 
two dollars per gallon and 50 hours per year flying to make up the 
difference in engine cost. At 500 hours and $100 per exhaust 
valve not counting miscellaneous labor and parts it is cheaper 
to burn the gas.

Range is another matter. It is hard to beat an O-200
running lean of peak EGT.

Paul Lamar
 
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