I fly a Lancair 235/320. The O-320-A2B engine has been modified with
9.5:1 pistons, and retains a carburator and bendix mags. As configured,
I estimate about 170-175 HP at sea level. Empty weight is 1033 lbs.
Sea level top speed is 200 kts at 2700 rpm. The prop is a fixed-pitch
wood Aymar-DeMuth (78x64). My climb rate solo is a bit over 2000 fpm at
120 kias.

At 10-12000', cruise is ~160-165 kias (192-197 ktas), burning 6.6 gal/hr.

The higher compression ratio improves horsepower for the same fuel burn,
and power at high altitude. Injectors will not improve horsepower,
but might run smoother LOP compared to a carb with poor fuel
distribution to the cylinders. I routinely run LOP at altitudes above
10,000'. Electronic ignition (variable timing) may improve your
power at high altitudes, but will probably have little effect
down low where the charge is easy to ignite and 25 deg BTDC about
right anyway.

Compared to an IO-360 (180 HP), my configuration is lighter and burns
less fuel. I often fly formation with IO-360 equipped LNC2, and find
that they can outrun me in climb and cruise, though they are burning
a few more gallons per hour to do it. Flying the 320 solo is about like
flying the 360 with a passenger.

Another factor is fuel types. The high compression 320 will require
leaded fuel (100LL). A lower compression IO-360 might tolerate
mogas, though there are other considerations - like "will your wings dissolve
in ethanol?"

To put it in another perspective, the difference between an O-320 and O-360
is probably less than the difference between a fixed pitch and constant-speed
propellor. The C/S prop costs $8000 more, adds 20-40 lbs weight, and
gives the same cruise speed. The real advantage of the C/S prop is in
allowing shorter takeoffs and landings with steeper climbs and descents.

-bob

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