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High DA engine break in

Penguin

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I've read all of the threads here along with the mfgr's break-in recommendations. My 150hp is graduating to a 160hp and I'll have to break it in here soon. I'm already hunting for a cruise prop to rent for the first 5 hours on the motor for the manifold pressure, then I'll put the Borer back on (also being overhauled and repitched from 43 to 42).

What I can't seem to find is any data for breaking in a motor at high DA. We're 6850'MSL here, and typical DA this time of year is 9000+. I'm likely only making 70% power as it is. The SB says 5000'. "DA in excess of 8000' will prevent engine from reaching sufficient cruise power for an acceptable break in..."

I can wait for a cold day here. Even then we'll be 7000'+. After the first hour overhead the field I can fly east 30nm down to 5500' MSL for the next hour, and I think that will help. Other than that, can anyone offer any guidance or lessons learned while breaking in a motor at higher DA? Typical OAT is 75 F.
 
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Wait until the weather cools off if you can. I’ve done 8 engine/cylinder break-ins and the only one that didn’t work out was when the DA was over 6,000 (in August/September). My last break-in (last month) was all at DA higher than 5,000. Field elevation here is 4,320. Keep the mineral break-in oil in it until the oil consumption stabilizes. Flying to a lower field elevation as soon as practical will help considerably. Run hard (2,500-2,700 rpm) and richen the mixture to keep the cylinders below 400 and oil temp below red line.

That’s my 2 cents. I hope your break-in goes smoothly.

windy
 
Why are you increasing horsepower and reducing prop pitch????? If anything, the pitch should increase.
 
Why are you increasing horsepower and reducing prop pitch????? If anything, the pitch should increase.

"I'm already hunting for a cruise prop to rent for the first 5 hours on the motor for the manifold pressure" I think that is what he is doing. Using a cruise prop (higher pitch) for the break in.

sj
 
Just go fly it. I was based at an airport at 7200' MSL for 32 years and never had any break-in issues. On your first flight, fly at a safe altitude, but stay as low as reasonable and give it a good hour or two at a high throttle setting. Most of your break-in happens in the first 60 - 90 minutes. After the first couple of hours, I resumed normal operations. I've broken in new and overhauled engines this way, with steel, chrome, and nickel cylinders. I have never had a problem with breakin and have never had an oil burner or compression issues with one of my overhauls. I don't go crazy over break-in oil either. I run Phillips 20-50 AD oil starting with the first flight. But no synthetics until everything is properly seated.

-Cub Builder
 
Cruise prop just for the break in, then yes, I am reducing the pitch on my Borer. After reading a bunch & talking to a lot of folks, the 42 on the 160 seems to be the right combination.
 
I've heard it really helps with the "break-in" if you can do a "run in" on a test stand first..
 
I don't have a test stand option. The plan is to tow the plane to the runup, run it, shut it down and take a peek for leaks, then start her up and go. If I head 70 NM south I can get down to 3000' MSL. I'll fly a few laps overhead then head south and fly there for 2 hours. Land there, check again, gas up, lather, rinse, repeat.
 
"I'm already hunting for a cruise prop to rent for the first 5 hours on the motor for the manifold pressure" I think that is what he is doing. Using a cruise prop (higher pitch) for the break in.

sj

I’m jumping in at a weird spot, but...engine break in.
I got the first two hours in yesterday on a 36* rainy day. I’m planning a couple more today, hopefully still in the low 30* ambient temps before it drops to highs of 20’s and even down to single digits. Is that too cold for break in (some people are saying it’s too cold)?


Sent from my iPad using SuperCub.Org mobile app
 
I ended up keeping the Borer on the 160 for the break in. I flew locally at 8500' DA for about 20 minutes, 1000' above the field. Landed. Checked for leaks, then took off again and headed south 100NM where I could get down to 4500'. I circled there for a couple of hours. Landed. Fueled up and did it again. Ran it hard. 3 days of that and she was all broke in. Good compressions, CHT settled in nicely. No leaks.
 
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