Lyc O-235-C Unerstanding Power/RPM Curve

[Gilbert DRIEUX]

Please,
I fly a Lyc O-235-C-2-C
How to understand the "Power and Fuel Consumtion Curve" NO 8210 in the Lycoming "Operator's Manual" ?
I beg your pardon for my poor english. :oops:
Their are 2 curves. I don't understand what the difference is, and witch one to concider  for my engine's actual data at static RPM and in fly figures.  :shock:

BHP = Brake Horse power; Ok. (Prony, etc. ...)
CORR. = ?
Propeller load vs Full throttle : What is the difference ? A lot of HP can I read, but which one to concider according to my actual cockpit data ?. :shock:
Present static RPM is 2200 (not more...), at 470 ft (LFPF @ Paris-France).
Frogs eater, yes ! :lol:

Regards, and thank you for your help and explainations.
It's now 2300 CET. Suggest, it's time to go to bed for me  :wink:

[Delta Mike]

The prop is a factor in how much static RPM can be developed.

My 253-C2C was not able to get past 2250 static at Durango field elevation ~7000 ft. I was advised it was not suitable for flight until it could make at least 2400 static.

In pursuit of 2400 static, mag was overhauled, new plugs all around, checked leads with high tension testser, adjusted valve clearance, adjusted timing to 27° BTDC, installed direct ram air intake, installed Lightspeed electronic ignition - all of this got me to 2260 static.

Finally the cylinders were removed for repair, since one was leaking on the intake during compression check. It turned out all of the intakes were leaking, which unbalances the intake flow at the high end resulting in power loss.

Since the cylinders are off, it is not too much to put new pistons (like a L2C) to make the compression 8.5:1 from 6.7:1.

I have yet to run the repaired engine, but I sure expect it to get up to 2400 static.

[spy]

  i too have a 0-235c1b....and based  out of las vegas.at 3400 ft... the only true change i got in  static and dynamic RPMs  was using the proper prop  i went through 4 diffrent ones....  till i got just the right one for my 0-235...static 2550...and flying full forward  at 2800 flat... thats with the stock mags....

[Gilbert DRIEUX]

Thank you Delta Mike and Spy,

I'll proced to more investigations and check on the engine. But until now, all seems ok on it. 2 mags.
The propeller is EVRA 63"-65"-53" (don't know exactly what 53" means...."corde" in French) => propeller's blades look "large" ; 6" at 16" from center.
I'll try to "rent"  :roll: from an French Canardian such an 60*74 sterba you fly Spy.
I don't intend to fly fast, fast, and fast, but w an O-235, I'm heavy, so I'll greatly appreciate to get max HP for take-off, and fly after at 70-75%, ro less.

 :?: My pending question is : How to understand the 2 curves on the engine diagram N° 8210 in engine OPRERATOR'S MANUAL ? :shock:
With 2200 rpm, is the available power 60HP or 85HP ? ("Propeller load" or "Full Throttle" curve ?)
Regards.

[GlennBob]

Delta Mike,

What will you do if you don't get to 2400 rpm ?  I doubt that you will.  You may never make more than 2250 on static run up , but when in flight you may easily get 2450.

Hope it was worth all the $ $ $.

Glennbob.

[Delta Mike]

Well Glenbob, that'll be a bridge to cross when I get there.

Given the intial condition rpm was 2250 with leaking intake valves and 6.75 compression, and the final condition will have repaired cylinders and 8.5 compression, I sure have some expectations of 2400.

It's not so much the $$$ as it is the lost time in the troubleshooting and repair. See, I've not been able to get so far into engine maintenance without noticing all the other things that need attention. Instrument panel, wiring, starter, gear, airbrake, firewall, fuel system, engine mount, baffeling, cowling - to name a few.

Delta Mike

[GlennBob]

Delta Mike,

Sounds like you're in the same fix I'm in.  I'm re-doing my panel, as the original had no gyros, and no IFR Navigation.  Also, no paint,  poor location of oil cooler, and exhaust pipes,. . .so much to do. . .so little time, . . time I'd rather have spent flying ! !   Soon . .I hope.

Glennbob

[Jack]

Thank you Delta Mike and Spy,
I don't intend to fly fast, fast, and fast, but w an O-235, I'm heavy, so I'll greatly appreciate to get max HP for take-off, and fly after at 70-75%, ro less.
.

Your in the old climb prop Vs cruise prop debate.  Assuming your running a fixed pitch prop, you don't want max RPM at static because you should pickup a short 100 Rs on the roll.

A fixed pitch prop is always a compromise between max performance on the engine at takeoff or cruise.

Tis reason on constant speeds they can reach max Rs for takeoff. Their blades move. Constant speed props are also more complex and can have failures.

If your over 2200 Rs you should be good to go. If your too heavy probably need to cut your fuel load down.  I can safely say with a full bag of 50 gallons of fuel and a pax in the back of my Long it takes a bit of runway to get off.

Cheers;

Jack