Is my engine broken in?

[JimWoo50]

I now have approximately 42 hrs on my 0-320 channel chrome cylinder engine and need some advice as to whether I should continue to run it hard. The engine uses about a quart every 10 hrs and the cht has never been over 400 deg. F. and seems to be trending lower. Currently there is mineral oil in the sump and after 22 hrs the oil looks brand new. I use 5 qts as a baseline level and pour the oil in by the ounce to maintain it. The belly of the plane accumulates oil but not a lot as my breather is routed down my gear leg. At my 20 hr oil change there was minimal metal in the screen.

The engine runs great and the plane is a blast to fly and it would make me sad to have to take the engine apart and rehone the chrome and not be able to fly it because I glazed the cylilnders. Thanks for any forthcoming help as I got conflicting advice from the local gurus with some saying climb up to 10k and run full throttle which I did and others saying stay down low and run it at 2400 rpm which I also did. Now I would like to undertake more extensive airwork, which involves more throttle movement and supposedly the risk of glazing the cylinders, and be confident that I am not damaging the engine.

[rocketbob]

You don't have a problem, qt/10 hours is pretty good for a chrome cylinder engine. Get an antisplat.aero seperator and be done with it.

[131RB]

I agree with Bob. 10 hrs to a quart are good numbers for channel chrome. Change the oil and have fun!
Ryan

[RV10inOz]

Was probably run in 35 hours ago, or 30 at the extreme.

Enjoy

[N427EF]

I agree that your engine is probably broken in and looking at your oil consumption it is fair to say that you have not glazed your cylinders.

A couple of things to think about:
Your Channel Chrome cylinders will take quite a bit longer to break in than the more commonly used nitrided Steel barrels where break in occurs in the first few hours.
Although it appears that your engine is broken in, it won't hurt if you continue using mineral oil for a while longer. Straight mineral oil, unlike the ashless dispersant variety does not hold particles in suspension and therefore looks clean on the dip stick.
The significant difference between ashless dispersant oil and straight mineral oil is the additives in "W" oil.
While the crosshatch honing marks on your cylinder barrels are left to allow a thin film of oil to stay between piston and cylinder wall for lubrication,
it is imperative for proper ring seating that the oil film is ruptured during the break in period and a certain amount of metal to metal contact is achieved
between piston rings and cylinder walls. It is the additives in ashless dispersant oil that prevents the rupture of the oil film during the break-in process.
To achieve this result you must do so by operating your engine at high power settings to generate maximum pressures in the cylinders and force the ring set against the cylinder walls. Metal to metal friction results in extremely high surface temperatures along the cylinder barrels and may result in the dreaded "glazing". This is why engine manufacturers caution against long ground running, slow climbs and generally engine operations that result in overheating during the break-in process.
In fact most of the operating procedures during the break-in period are also good after you are done with it. There is no documented evidence that "babying" a lycoming prolongs engine life.

You are not doing yourself a favor by not filling your oil to maximum level during the break-in period. If you rapidly loose the first quart you can assume that you still have excessive crankcase pressure and therefore your rings have not yet completely seated.

My all measures it appears that you have an excellent engine and shouldn't have to worry about break in procedures any longer.

[Gash]

Ernst,
That was a very useful and informative post, thank you!