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Engine break-in question

airguy

airguy

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On a new or overhauled engine, break-in is ideally done with a high power setting. I've seen some guys advocate "run it like you stole it" and others say 75% power. At my location, maintaining a couple thousand feet above my private strip, about 85% power is the best I can do and that's running wide open throttle with the RPM at 2650. Is this really the desirable way to do it, or is 24"/2400 a more reasonable and acceptable way to build time on the engine for break-in?

I had a high oil temp indication on my first flight, I was running it like I stole it and it climbed up to 230F before I pulled it back. The temp dropped slowly at 75% power so I'm thinking this is simply a break-in heat load and I'll eventually be OK.

I also have some window screen that I put in the 4" duct for the oil cooler coming off my plenum to keep bugs and debris out - I'm going to remove that before the next flight to improve airflow, at least until I know my rings are set and the oil temp comes down.
 
Since I was flying above mountaintops for the majority of Phase 1, 75% was about all I could get. Break in went fine.

Just an anecdotal data point.
 
How were your CHTs? My understanding is run it as hard as you can while keeping the CHTs under control. Otherwise you run the risk of glazing the cylinders and your break-in will have been for naught. That's the real area of concern IMO.
 
CHT's were actually great - I was running slobbering rich and my spread was from 340F to 365F coolest to hottest, with an OAT of 55F running it at 85%. The only issue I noted was the high oil temp, but I can improve airflow to the firewall-mounted cooler by removing that screen for a while.
 
Aaahhh - some good info there in the second document - I pulled the power back when I saw 230F on the oil temp, Lycoming calls 245 max, that's good to know.

And no, my engine was not run on a test stand. I got it as 105TTSN 0SMOH and the only runtime on it was my few ground runs and taxi tests, where I always shut it down when my top CHT came up on 250F. The Sam James plenum seems to do a very good job of controlling the CHT's, though it was murder to fit on the baffles, it was a very poor fit out of the box.
 
I have been in aviation since 1974, used to work for a major engine manufacturer. I really have never understood what I perceive has a myth.
I am a A&P, IA and have been around aircraft and auto engines for a bit.
And here's my two cents worth, I and I tell my customers to wArm there power plants up thoroughly( at least 5 min. Summer, maybe 10 min. Winter) and then
Just enough power to taxi the aircraft to run up area and Slowly bring up
RPMs to run up. Then what ever is necessary to taxi to departure end and
And slow with the throttle. (Everyone knows cold shock?) think?
About heat shock. Aluminum piston steel cylinder? expansion rates?
Now every one has there own opinion( trump, Hilary etc) same with engines
But let me say this, I flew my C210 from the mid west to California and back over the new year, stopped Santa Fe, final destination Jone Wayne(SNA)
With sight seeing a total of 17.4 flight hours and I lean it like a diesel.
All cylinders have about 800 hours on them.
Used about a pint of oil... Total oil used.....1 (one) pint
BUT I have told my customers after about 25 hour of babying
There engine then run it hard for a couple hours and we will look at it
 
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