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Is it broken in?

M

Michael Henning

Well Known Member
I am running an ECI IO-360, Cerminil cylinders(group "A"), 9.5/1 pistons. 3.3 hours on engine so far. CHTs were in high 300s at beginning of first flight and were coming down to mid 300s by the end of that 30 minute flight. Running mineral oil for the first 5 hours, then switching to multi-weight oil.

The CHTs have stabilized at 325 degrees (cylinders 2-4 are all within 10 degrees of one another) and cylinder #1 is running at 285 degrees. The power setting is 25" MP/ 2500 RPM. I am planning on balancing the injector nozzles to bring up the #1 CHT.

Thoughts/ Comments? Is this engine broken in? It has burned less than 1/2 qt, and not burning any now.
 
That sounds pretty good to me. If anything, maybe not hot enough. It's hard to judge oil usage in 3.3 hours. You want it to be using some. It should go through a quart every 20 hours or so.
 
Thanks Jesse. I am now able to really start flying it, so I will have more data to make conclusions. I had the prop "balanced", from the factory it was .07 IPS, and the tech wasn't able to get it any lower than that. It is very smooth.
 
The power setting is 25" MP/ 2500 RPM. I am planning on balancing the injector nozzles to bring up the #1 CHT.
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Michael,

First of all, engine break in is usually over in the first few hours. 5-6 is enough and by the 10 it is most surely. I hate people using the old 25/2500 as being some kind of perfect setting, but in any case this will have given you about 80% power when ROP. I assume you left it full rich. You could have done in LOP but used 27"/2500 and achieved the same power but cleaner and slightly wider range of average pressures, but that is not the question here.

Please DO NOT do this: "I am planning on balancing the injector nozzles to bring up the #1 CHT" as this is a REALLY bad idea.

This is akin to saying three of my tyres are a bit more worn than the 4th one so I will let 20PSI out and wear it down to match the others.

Balancing your cylinders is all about matching the Fuel/Air ratios. That is getting a good GAMI spread, for you that is about 0.3 GPH between when the first EGT peaks and the last one peaks. 0.5GPH is the line in the sand but I find on the 4 cylinders you want to get more like 0.3.

This then gets the engine working right. The HEAT IN part of the equation is fixed. Now is the time to look at baffles and getting the CHT's at a reasonable level in climb and cruise. What is reasonable? A big rubbery zone, but if I use my RV10 as an example it would rarely get above 380 in the climb except on a very hot day and not by much, and once cruising around 355-370 if ROP and 325-350 LOP on a hot day and about 15 less on cool days.

If you get your CHT's within 25-30df of each other and they are all good. Life is good. Dan Horton has good posts on baffles etc.

If what I wrote above is not 100% clear, PM me so we can discuss it. Never ever monkey with injectors to fix a CHT.
 
Break in

You may be mostly broken in but 3.3 hrs is very early in the game. I would be leery about switching away from mineral oil too early. What I recommend to clients and on my own fresh OH IO320 is 10 hrs on mineral oil then change the oil & filter. Put mineral oil back in and fly another 20 to 40 hrs before changing to whatever oil you will run after break in. I consider the engine broken in when the cht's, oil consumption & wear metals all have stabilized. There is no downside to running mineral for 50-100 hrs but a possibility of jeopardizing the break in by switching too early.

Don B. A&P. IA

RV 9. Rebuild in Progress
 
Old scholl here.

This is just me and not out of any book. I like to think two oil changes for break-in. The first at 10-15 hours the second 20 hours after that. If all the temps and oil consumption settles down by then and you don't see any thing in the filter after the second oil change then have at it and go on a regular bases by the book. I would not start adjusting fuel flows unless one was way out of line until at least 50 hours into the hobbs time on a new engine. It is your engine and your call, but old school has served us well in the recp. market for a long time. Yours most respectfully. R.E.A. III #80888
 
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Michael, It has been pretty cold around here lately. I have been watching my CHT's pretty close lately too. I am interested in seeing what happens when things start to really warm up around New England. Maybe we can meet for breakfast or lunch and chat about it.

Shoot me a message.

:) CJ
 
Many Thanks

Thanks for all of the replies, I really do appreciate it. as I am not an engine guy. Dave- I spoke with Don at Airflow and he is going to work with me on balancing the injectors and I am reading DHs posts on baffling.
 
Break-in

New Lycoming engines from the factory are broken in before shipping. Nevertheless, Lycoming says continue mineral until 50 hours of operation. Might be good to wait a bit before going to multigrade detergent. Let us know how it all works out. Wish mine broke in so rapidly!
 
Broken in?

RV8JD. My Lycoming O-360 series operator's Handbook says "New engines have been carefully run-in by Lycoming and therefore, no further break-in is necessary insofar as operation is concerned; however, new or newly overhauled engines should be operated on straight mineral oil for a minimum of 50 hours or until oil consumption has stabilized. After this period, a change to an approved additive oil may be made, if so desired." So you're right; the term used is "run-in."
 
Takes time

I was just thinking about this subject yesterday and ran through a few numbers....

Lets assume a theoretical guy takes an engine apart for a crankshaft AD or something...While he is in the engine he has the case re-worked, all new main bearings, Rods re-sized, new rod bearings, new wrist pin bushings, etc. however he re-uses the original cylinders that have been running fine on his airplane for hundreds of hrs. The guy took really good notes prior to the engine work and now he thinks the plane is slower by 3-4 knots.

At RV speeds, our theoretical guy is noticing only a little less than 2% speed reduction.

Theory says that the horsepower required cubes with flow so the horsepower difference would be about 5%.

Using my airplanes information for calculations I have something maybe over 260 hp so at a normal 70% cruise make about 182 HP.

5% of a 182 HP engine is 9.1 horsepower.

9.1 horsepower is about 23,150 btu/h. now hold that thought for a min.




Most people agree that an internal combustion engine puts out about 1/3 power at the crankshaft, 1/3 of the power as heat in the exhaust, and 1/3 of the power as heat through the cooling system (in our cases the cyl heads, oil cooler, case, cylinders, etc).

So..if 1/3 of the energy is coming out as heat, lets try to quantify this. The 540 i run as comparison uses about 12 gph of fuel in cruise which has 18,700 btu/lb. so that comes to 1,346,400 btu/hr and 1/3 of that is 444,312 btu/hr that is being rejected through the cooling system(s).

Now if normally there are 444,312 btu/h coming out the cooling system and the amount of additional heat required to slow the airplane down the said amount is 23,150 btu/h, that is only an additional 5% of heat. I don't know if there can be that much drag on new bearings or not but it was good mental exercise.
 
It may suprise you.

Weasel said:
I was just thinking about this subject yesterday and ran through a few numbers....

Lets assume a theoretical guy takes an engine apart for a crankshaft AD or something...While he is in the engine he has the case re-worked, all new main bearings, Rods re-sized, new rod bearings, new wrist pin bushings, etc. however he re-uses the original cylinders that have been running fine on his airplane for hundreds of hrs. The guy took really good notes prior to the engine work and now he thinks the plane is slower by 3-4 knots.

At RV speeds, our theoretical guy is noticing only a little less than 2% speed reduction.

Theory says that the horsepower required cubes with flow so the horsepower difference would be about 5%.

Using my airplanes information for calculations I have something maybe over 260 hp so at a normal 70% cruise make about 182 HP.

5% of a 182 HP engine is 9.1 horsepower.

9.1 horsepower is about 23,150 btu/h. now hold that thought for a min.




Most people agree that an internal combustion engine puts out about 1/3 power at the crankshaft, 1/3 of the power as heat in the exhaust, and 1/3 of the power as heat through the cooling system (in our cases the cyl heads, oil cooler, case, cylinders, etc).

So..if 1/3 of the energy is coming out as heat, lets try to quantify this. The 540 i run as comparison uses about 12 gph of fuel in cruise which has 18,700 btu/lb. so that comes to 1,346,400 btu/hr and 1/3 of that is 444,312 btu/hr that is being rejected through the cooling system(s).

Now if normally there are 444,312 btu/h coming out the cooling system and the amount of additional heat required to slow the airplane down the said amount is 23,150 btu/h, that is only an additional 5% of heat. I don't know if there can be that much drag on new bearings or not but it was good mental exercise.
Click to expand...

We used to have a saying, that we could tell when a racing engine was about ready to come apart by how well it was running. When they got very lose and where putting out their most they were also getting close to coming apart. For the street we would build say a Jag. or Roles engine or rebuild one. We knew it was tight and needed to be run in before it went out the door. We would build it put in in the frame and let it set there and run 16-20 hours. Then pull it out tear it down. Read all the bearings and wear points. Put new bearings and gaskets back in if we did not see anything a miss and then let it run another couple day at idle before we started putting it under load. Then we would send it out the door and call it back in a couple of weeks for an oil change and issue a warning to take it easy for the first month or so to let it "break-in". Seating the rings is only one small aspect of a break-in. You can most often go back and re-ring an engine at any time after a good break-in of the end. But you need a good true set of cases and no hot spots on any of the bearing surfaces and you need those interaction surfaces to wear in nice and easy and true to one another along with the lifters, tappets, gear faces, extra.
It is as much an art as a science. Keep them cool, light, well lubed, and under as little stress as you can and they will last for ever. Run them hard, hot and under a lot of stress and they blow up shorty after 500 miles or the equivalent number of air hours. "B.M.E.P." Hope this helps somebody. Yours as always. R.E.A. III #80888
 
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