Ben Hallert wrote:
Howdy,

Just for comparison, the O-200 puts out 100hp at like 5-6gph of av gas,
right? Whether or not the engine mentioned can do it, it seems
difficult to believe that the O-200 is the height of efficiency. 100hp
at 4gph doesn't seem like that far of a stretch when compared to the
burn on the O-200, I guess, especially when energy denser fuels than
avgas exist.

That said, I don't understand what the bourke engine is supposed to do
different to get the numbers it describes, like another poster
mentioned, it looks like a two cylinder rotary.

Most internal combustion engines (including the O-200) have a BSFC
between 0.4 and 0.5 pounds/hp/hour.

I'd say an O-200 puts out 100hp at about 8gph, 5-6 gph is a typical
cruise fuel flow. 100hp is at sea level, wide open throttle, max rpm.
You don't spend too much flight time in that regime.

The O-200 is not the height of efficiency, but it isn't the height of
inefficiency either. From an engineering perspective, 0.25 lb/hp/hr is,
uh, extraordinary to say the least. Think of it like the internal
combustion engine's answer to cold fusion.

Also, consider which definition of energy density you're using. Avgas,
Jet-A, and kerosene have virtually the same mass energy density (avgas
is actually about one percent greater than Jet-A). A gallon of avgas is
lighter than a gallon of kerosene (and/or jet fuel, diesel), so it's
_volumetric_ energy density is less.