This is for the vaunted Lycoming O-360-A4M
or O-360-A4A 180 HP running at peak EGT.
No longer allowed by Lycoming BTW.

Compression ratio is 8.5 which sounds a bit
marginal for auto fuel and such big cylinders.
The bore is 5.125 inches in dia. for $%#@^ sakes!
The book says use 100LL.

Piper did not publish BSFC directly in this
book so we have to derive it from this chart.

The endurance with 48 usable gallons at 2000 feet
is  7.4 hours at 55% power. That is 6.49 gallons per hour.
6.49 gallons times 6.1 pounds per gallon is 39.59 pounds
of fuel per hour. 55% of 180 HP is 99 HP.
39.59/99 = .40 BSFC. Excellent.

This is a carb engine with a bit of continuos carb heat by
virtue of the fact the intake manifold runs through the oil
pan. Must have good mixture distribution. The runners are
also equal length unlike the runners on my O-470.

At 65% max HP or 117 HP the engine burns 7.9 gallons per
hour or 48 pounds per hour. The BSFC is then .41.
At 75% power (max power level allowed for leaning of old Lyc engines)
The burn is 9.1 gallons per hour or 55 pounds per hour.
HP is 135 and BSFC is again .41.

Outstanding engine for low fuel consumption. Probably due to
low friction as the engine has few cylinders for large displacement.
Fours always do well when it comes to fuel economy.

Yeah. I get my Lyc IO360 with fi and flow balanced cylinders (just over
200hp on dyno-210+) down to 8.5 gph (2 flow meters installed) 25 degrees
rich of first peak at full throttle with no roughness all the time when
I am below 75%, which is the majority of the time at altitude. Very
efficient engine....which is one reason why the Lyc IO and O 360 are so
popular. It is a good engine for LOP operation a cruise altitudes and
whenever your hp is down (like descents, high altitude anywhere). It is
a hard engine to beat-usually has a minimal number of problems as well.
It should be our target to shoot for. The benchmark, so to speak.
Marc Wiese

I don't believe it Marc. 75% of 210HP is  157.5 HP at 8.5 gal per
hour or 51.85 pounds per hour is a BSFC of 0.329.   You must be joking.
Which liar/incompetent ran the dyno? Who needs diesel engines?

Next thing you know these Air Craft engines will start to fill the tanks
with fuel as you fly :-)>

Paul Lamar

Paul,

He said "below 75%".    Could be 55%, which gives 0.44.
Switch to decaf.  :-)

Bill
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

That is not the message he wanted to get across. Below 75% also
means 74.999999%

I don't drink coffee.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org