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  #1  
Old 12-20-2019, 06:39 PM
ivana ivana is offline
 
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Default Duct for engine break in

I want to break in my engine on the ground and on the plane. I'm looking for plans to build a duct to accomplish this. Anyone know of such?
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  #2  
Old 12-20-2019, 06:49 PM
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rmartingt rmartingt is offline
 
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An old thread on this just surfaced a few weeks ago: http://www.vansairforce.com/communit...ad.php?t=86912
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  #3  
Old 12-22-2019, 12:30 PM
ivana ivana is offline
 
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Default ground break in

Thanks for the link. My search skills are lacking.
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  #4  
Old 12-22-2019, 02:39 PM
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DeeCee 57 DeeCee 57 is offline
 
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on the ground...?

Go and fly your serial home built, it’s a proven design, will fly for sure, and breaking in an engine whilst flying is way better than on the ground
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  #5  
Old 12-23-2019, 01:51 AM
svyolo svyolo is offline
 
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You can google or youtube. There are videos on youtube of guys doing it. I will be doing it. I wish I could post pictures here but never figured it out.

Most are just a simple shroud on top of the engine, attached to the cylinder heads at the same bolts that hold the normal cooling tin. I will make a frame out of 1" square tube, because I have a bunch of scrap. Cheap sheet metal or even plywood inside of the frame to direct the air down through the cylinders. I heard a basic rule of thumb is 1 sq foot per cylinder for the front opening.

It ins't very complex.
https://www.flickr.com/photos/103579181@N02/13088303975

Last edited by svyolo : 12-23-2019 at 02:26 AM.
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Old 12-23-2019, 06:59 AM
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jcarne jcarne is offline
 
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Just out of curiosity, what is the reason for wanting to do it on the ground? Sounds boring unless you have an iPad and few movies to watch.
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  #7  
Old 12-23-2019, 08:35 AM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by jcarne View Post
Just out of curiosity, what is the reason for wanting to do it on the ground? Sounds boring unless you have an iPad and few movies to watch.
One reason is altitude. In order to get a good break-in, you want to run high power, and if your airport is a mile (or more) above sea level, you simply cant get enough thick air to get above 80% power - especially if you want to have a little altitude between you and the ground during those first few flights.

I know of at least two airplanes here (about 4700’) that have glazed cylinders during their first few flights with new engines because they wanted to fly a few thousand AGL over the airport and just couldn’t get the power.

Paul
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  #8  
Old 12-23-2019, 10:57 AM
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jcarne jcarne is offline
 
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Quote:
Originally Posted by Ironflight View Post
One reason is altitude. In order to get a good break-in, you want to run high power, and if your airport is a mile (or more) above sea level, you simply cant get enough thick air to get above 80% power - especially if you want to have a little altitude between you and the ground during those first few flights.

I know of at least two airplanes here (about 4700’) that have glazed cylinders during their first few flights with new engines because they wanted to fly a few thousand AGL over the airport and just couldn’t get the power.

Paul
Oh how interesting, thanks for the explanation Paul. Something I may need to ponder more as I'm at 4251'.
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  #9  
Old 12-23-2019, 11:26 AM
Jpm757 Jpm757 is offline
 
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Is your engine a factory Lycoming? If so it has been test run and semi broken in. If so, give it a good leak and operational check and go fly it. I agree with Paul, the more you fuss with it on the ground, the more likley you are to glaze the cylinders and screw up the break- in.
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  #10  
Old 12-23-2019, 01:33 PM
Canadian_JOY Canadian_JOY is offline
 
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There's a big terminology gap here that we have to bridge.

1) Run In - this is what Lycoming does at the factory. So many minutes and such-and-such RPM, then so many more minutes at another RPM. That's RUN IN. Done for you at the factory or any half decent engine builder.

2) Break-In - this is what you are doing on the airplane (unless you have done the overhaul yourself). This is where you are running the engine hard at high power setting to seat the rings.

I can't think of any good reason other than the altitude consideration for a ground-based break-in. The engine will be getting great big gulps of cooling air when you do break-in in flight. Boring holes over the airport at 75%+ power setting isn't all that tough to do. You'll be getting to know your airplane, and your engine. Then if you're lucky you'll see that "aha" moment when the temperatures start to settle and you'd swear you can feel the engine running more smoothly.

Unless you have troubles getting the engine to produce full power, thanks to density altitude concerns, flying it seems the most reliable method of breaking in.

Oh, just thought of another reason you might want to break it in on the ground... If you're located at an airport where you can't be reasonably assured of short ground run times before takeoff and after landing then you might want to do the first few hours under a cooling hood.
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