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engine break-in question

Use the Sensenich prop for higher MP.

Nothing wrong with below freezing temps, better than above 80 temps... Carry some power in to land/ high drag with a shallow approach.

How confident are you in your (or your A&P's) work? Double and triple check everything... You are the flying test stand, key word "test"... Stay in the pattern in the orbit mode. Above 75% power setting... Do an hour, if it looks/feels good stay up for another hour... Land and do a quick check, you are looking for oil/fuel leaks and loose parts...top off the oil sump. Run at max oil level!!! Oil absorbs and removes heat...

It only takes a couple hours to seat the rings (if done properly) you are looking for a drop in CHT, and oil consumption. Follow the Lycoming instructions for engine break-in. Make a log book entry stating that you did I/A/W...don't exceed the airframe limitations when using high power settings...
 
% of power is dependent on manifold pressure and RPM depending on prop---With borer props these engines are loafing in level flight and anything under 2600 RPM---with a 82/41 prop at 1000 feet I get 20+- inches at 2500 RPM --way below 75%
 
Interestingly on my first flight my oil temp worked its way up to 225 over the course of the hour.Since then it has only reached about 185 with a similar OAT. Anyone have an opinion on when oil consumption is acceptable. Most the airplanes I've been involved with have used more oil than I wished. For instance our PA 18 95 uses a quart every 4 or 5 hours.
 
Breaking in advice?

Just zero-timed my O-320 A2B and put high compression pistons in to bring it up to 160HP.

Any advice re breaking in beyond the usual: run hard 25 hours, mineral oil etc?
 
Agree on running hard. Flew my A2B at max rpm for two hours before reducing throttle for landing. Used Philips XC which has a mineral base. Compression check after 25 hours, all cylinders 79/80.
 
It may not take 25 hours. Watch your CHTs and oil temps. You will see a noticeable temperature drop at the time when it is broken in.
 
I merged your thread with several more on the subject. I run it high manifold pressure with a standard prop, not a Borer because of the low manifold pressure of the Borer.
 
High manifold pressure is a function of the throttle. A Borer is called a climb prop because it will allow you to climb out at WOT. You must pull it back in cruise to avoid overspeed.

A cruise prop will allow you to cruise at max without overspeed. Unlike the Borer, it will overspeed at normal climb airspeeds and WOT.
 
Ditto. If it overspeeds in climb, you're way underpitched. I'm running an 82-42 on a 150/320 and I turn 2750 flat out and trimmed for level flight.
That being said, I'd still want more load for break-in.
 
Last edited:
Eddie Foy said:
My 82/44 Borer would overspeed in cruise at WOT. 160 HP.
Click to expand...
You originally stated it would overspeed at "normal climb airspeeds and WOT". If that's the case, you are indeed underpitched by a considerable margin.
A little overspeed at WOT / level flight is no big deal. I'd hazard a guess that a lot of us are pitched like that. If I crank mine open and keep trimming for level until it peaks out, I bust redline by about 50 RPM. Somewhere around 103 mph.
 
Eddie Foy said:
High manifold pressure is a function of the throttle. A Borer is called a climb prop because it will allow you to climb out at WOT. You must pull it back in cruise to avoid overspeed.

A cruise prop will allow you to cruise at max without overspeed. Unlike the Borer, it will NOT overspeed at normal climb airspeeds and WOT.
Click to expand...

I think you might have typo’d. I inserted a correction.
 
A cruise prop will allow you to cruise at max without overspeed. Unlike the Borer, it will overspeed at normal climb airspeeds and WOT.
Click to expand...

No typo?

I re-pitched an old prop to get redline on takeoff and didn't get any recognizable takeoff performance improvement but it sure did rattle the plane in high power cruise. I gauged the new Borer to achieve redline in level cruise. Takeoff and climb performance were good with that. New props work better than filed old toothpicks so my comparison is not apples to apples. Very few PIREPS for Borers are.
 
A cruise prop will allow you to cruise at max without overspeed. Unlike the Borer, it will NOT overspeed at normal climb airspeeds and WOT.
Click to expand...
I think the "it" refers to the cruise prop, not the borer.
 
My 8243 on 150 hp will go over redline in a climb but meets the STC static rpm. New break in procedures for ECI cylinders said you could use AD oil instead of mineral oil. I still use mineral oil for break in and a Sensenich cruise prop. It make a lot higher manifold pressure and I would rather not take the chance.
 
NO prop should overtach, or come anywhere close, at climb speeds.
Click to expand...
Agreed. I guess I was mistaken; I thought the discussion was revolving around the interpretation of Eddie's statement.
 
Meanwhile, back on the OP’s question... When I had my O-320 upgraded to high-compression, the shop said to run it flat-out as much as I could until a) the CHTs came down (were a bit high at first), and b) oil consumption dropped back to “normal” range. Three hours later, the CHTs were back to normal, and it stopped burning oil. I called the guy to be sure I was OK, and he said “Yeah, that happens every once in a while. If those two items are satisfied, you’re OK to return to normal operations.” That engine burned les than a quart of oil between changes (50 hrs) for the rest of the time I owned it...
 
Cylinder bores are machined with more precise processes these dys with less high and low spots so the rings seat in in 3-4 hours on most new cylinders I have installed.
 
My experience with six or seven new engines is that most if not all the break in occurs in the first three or four hours. As others have noted, once cylinder and oil temps have dropped off, most of the break in is done. I was always told to continue break in procedures (mineral oil, relatively high and varying power settings, no prolonged steep climbs, etc) till around 20 hours. That’s probably conservative, but engine overhauls aren’t cheap.

My current C-90 Continental spit quite a bit of oil when I first got it. Engine monitoring instruments are minimal, and the engine was low time (~ 20 hours smoh). I’ve run it hard, and somewhere around 200 hours, the amount of oil on the belly decreased significantly. I suspect that engine hadn’t been properly broken in, but running it hard eventually got it to settle in. That doesn’t always work, but if you don’t see those signs of break in (drop in CHT and Oil temps) keep running it hard. You never know, it may still settle in.

MTV
 
Whats the coldest temp one should break in an engine. Lycoming recommends not during extreme cold but doesn't give a number. Need to do it soon up north.
Thanks
 
thunderhead85 said:
Whats the coldest temp one should break in an engine. Lycoming recommends not during extreme cold but doesn't give a number. Need to do it soon up north.
Thanks
Click to expand...

id be reluctant to break in an engine at colder than about -10 F. But, at cold surface temps, you often have hard inversions, so takeoff in cold, climb to warmer air.

But out the bottom line is, can you afford to pickle and park till spring?

MTV
 
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