Paul,

Can you make sense of this posting... and how it compares to the
fuel burn
of the rotary?

Mark S.

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I have seen different conversions of fuel burned to horsepower
generated so I went back to the GAMI wizards for the details.
John-Paul said:

Typically, the 8.5:1 compression ration engines use 14.9 hp/gph while
the 7.5:1 CR engines use 13.7 hp/gph.
The TSIO-550-E engines use 24° BTDC timing and are a little more
efficient
that the typical 7.5:1 CR engines, though.
George speculates ~14.6 hp/gph.  Looking at the operation manual,
it looks
more like 14.75 hp/gph. <<<

So there ya' go. Take your pick.

Robert M. Simon
ES-P N301ES
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Nothing like using a non standard fuel burn number to
bamboozle your customers. hp/gph :) Gami has been at this
misleading stuff for years.  All designed to sell
matched mechanical fuel injection injector orifices.

It is something hard to prove as nobody knows how much
HP their engine is really developing while in the air.
That is why I harp so often on built in torque meters.

BSFC not hp/gph is the world wide standard.
BSFC means Brake Specific Fuel Consumption given
in pounds of fuel burned per HP generated per hour.
Weight of fuel is used for a good reason. The energy
derived is a direct function of the weight of fuel
burned and not the volume of fuel burned.

1 gallon an hour is 6.25 pounds of fuel an hour
at some standard temperature.

This volume number varies widely with temperature
so take claimed BSFC or hp/gph with a grain of salt.

6.25 pounds of fuel for 14.9 HP for one hour is a BSFC
of .42. Possible but unlikely.  The best numbers
I have seen are more like .45.

The current rotary, properly
leaned, is .47. Mazda claims a breakthrough for
the 16X. That could be as low as .41 to.43 when
it appears is my guess. Diesels are typically .38.
The R3350 turbo compound got down to .34 or .35
at 20,000 feet or so.

Cessna claims my C182 with a Cont. O-470 carb is
.5 BSFC or so as I recall. The EGT's and CHT's are
all over the lot. It burns 11 to 12 gallons
an hour at 8000 feet and about 150 MPH.

What kind of cruise numbers are you seeing
and what are the EGT's?

Paul Lamar



Specific Fuel Consumption (SFC) is defined by engine engineering conventions in grammes per kilowatthour or g/kWh (this unit is derived from SI)

I imagine in USA and commonwealth they sometimes still use units based on horsepower and pounds, and where pounds are not equal all over the world there is a risk of misinterpretation. You know like UK miles per gallon an US miles per gallon are not equal.

When you talk about consumption it is the power times time that should be the nominator not the mass.

Units remain difficult though it could be easy if all agree to use international standard.

With fuel purchased in the filling station the unit is liters (or gallons in some countries) so the alternate option would be liter per kWh. If you multiply this with the scalar milli (0,001) you would find values close to those in g/kWh which could leas to misinterpretations again. So watch out.

Regards fron Randolph