Best method for breaking-in new cylinders

[M20Kid]

Well, I took my 231 in to the shop a month ago to resolve issues with fuel flow, high oil temps, and oil blowing out the air/oil separator and found that I needed six new cylinders and an overhaul on the turbo charger.

The good news is that I get the airplane back this week but I'm getting conflicting information about the best method for breaking-in the new cylinders.  The overhaul shop says to run it at max power for two hours, drain the break-in oil, and go fly the airplane normally.  My mechanic says the engine shop recommends that because they want repeat business!  He says to run it at reduced power settings for the first several hours and keep the break-in oil in the engine for the first 25 hours.

I'm curious what others have heard about this and/or any experience you have with either break-in method - or another combination of power settings and break-in oil.

[garytex]

It is well established that high brake mean effective pressure is required to get new rings to expand outward enough to "break in" which means that they wear off part of a (usually) slightly angled part of the face of the ring to match the cylinder wall.  This needs to happen before the new cylinder wall glazes over with a patina of cooked on oil and becomes too slippery to do the required wearing of the ring face.  This is also why anti-wear agents are verbotten in break in oil.  These factors cause most knowledgeble engine shops to recomend high power settings for break in.  They don't want the engines back because of high oil consumption, which happens when an engine is babied on break in.  I concur, however my sample set is limited to very few engines personally.  However I run around with several AC mechanics, whose sample set runs to hundreds of engines, and they all sing the same tune.  Run it hard with very little idle time before takeoff.  Good luck,

Gary

[PTK]

Mike Busch in one of his webinars also recommends running it hard for an hour or so in the vicinity of the airport. I don't recall which webinar it was.

[N601RX]

The procedure is different depending on the cylinders.  It depends if they or plain steel, nickel, channel chrome or nu-chrome.  Each manufacturer has published detailed guidance, I would follow it.

[jetdriven]

I would submit they are both wrong, in parts.  Continental published pretty clear guidance on break-in of turbocharged engines, and they want 75% or greater power, with straight mineral oil for 25 hours. Other caveats as well. Follow them strictly.  Their document is available on Airpower.com.  APS recommends a 75% LOP break in. That will cause a smoother peak presure pulse and the maximum cylinder pressure occurs further down the cylinder, out fo the choke.   In any case, do not get the cylinders above 360-400 degrees.  Do not practice landings. Do not "baby" the engine.

[jetdriven]

I would submit they are both wrong, in parts.  Continental published pretty clear guidance on break-in of turbocharged engines, and they want 75% or greater power, with straight mineral oil for 25 hours. Other caveats as well. Follow them strictly.  Their document is available on Airpower.com.  APS recommends a 75% LOP break in. That will cause a smoother peak presure pulse and the maximum cylinder pressure occurs further down the cylinder, out fo the choke.   In any case, do not get the cylinders above 360-400 degrees.  Do not practice landings. Do not "baby" the engine.

I would add one thing further.  That low fuel flow on takeoff is much of the reason why you had to put cylinders on it. If you cannot get a 1275-1300 EGT on takeoff or you cannot maintain a 360 CHT on takeoff and climb, you will be putting another set on. On Continental engines it is critical to have sufficient fuel flow for cooling available.

[jetdriven]

here is something from Walter Atkinson, yea the 90% power LOP turbo Bonanza guy, who gets TBO out of them.       

Here's the breakin we use.

******     http://www.beechtalk.com/forums/viewtopic.php?f=37&t=5056&p=176825&hilit=breakin#p176825

Advanced Pilot Seminars
Engine Break-in Procedure
(requires LOP capability)

Put in whatever oil you plan to use for the TBO run.

1) Get the fuel flow set up ON THE GROUND which results in takeoff EGTs below 1275dF. Abort the take off if you do not have enough FF to keep the EGTs under 1275dF.

2) Make a full rich high power - cowl flaps open - trip around the pattern for 5—15 minutes. Land. Check for leaks. Fix stuff. Make adjustments.

3) Make a normal full rich full power takeoff and a 135KIAS climb to 1000 or 1500' AGL. Cowl Flaps OPEN. Then level off. Set cruise RPM. Leave the cowl flaps open. Do the big mixture pull and fly the airplane WOT x 2500 at about 16.5 gph and LOP for the next hour or so. If you want to vary the RPM down to 2200 or 2100 and back to 2500 or 2700, that is fine. If any CHT goes above 380F, lean it some more. If that does not work, land and see what is wrong. Otherwise, land, check for leaks and stuff that is “wrong”. Make adjustments.

4) Make a normal cross country somewhere and come home with about 4.5 to 6 hours total time on the new jugs. Land and drain the oil while it is hot. Cut the filter. It should have some metal in it. But no part numbers. During this trip, you should try to get the plane (fast cruise climb) up to 12 or 15,000' to “stretch” or exercise the rubber induction couplings and see if one will come off (you will know it if it happens!). Have the mechanic tighten up all the induction clamps after this trip to altitude.
Always keep the CHTS under 380F.

5) New oil. New filter. Engine is broken in at 4 hours or so. After another 15 to 20 hours, change the oil and check the filter (it should have about 5% as much metal as the first time.) Send oil out for first analysis.

6) Enjoy the airplane.

_________________
Walter Atkinson
Advanced Pilot Seminars

[jackn]

I did a 'Top End' last November on my K. This is what I did. 1st flight; 2 hrs 75% pwr, 2500 rpm, very rich(1350 EGT)(some will argue for lop). Removed cowl, checked everything! Did not change oil. Ran it at 75% 2 hrs/flight, very rich, varied rpm 2400-2500, for 20 hrs. Changed oil(oil analysis key). Next 30 hrs; fly normally, 65 - 75% pwr, lean normally, change oil(oil analysis). I used Phillip x-country, no additives, for first 50 hrs. Now I fill to 8 quarts + camguard. No oil on belly, uses approx 1 qt per 30 hrs, and oil stays golden. Key is to run hard but stay cool.

[jackn]

15 Hr oil

[Parker_Woodruff]

high power LOP.

[KSMooniac]

I did a high power LOP breakin on Aeroshell W80 (no +) in the spring a few years ago and it worked great.  I followed Walter/APS's recommendations that Byron posted above, except I didn't do a high altitude run since I'm normally aspirated.  My engine was broken-in by 5 hours, and continues to use very little oil and has great compressions.

High power and cooler CHTs are what you want... and the best to do that is high power LOP settings with the cowl flaps open.

[fantom]

Very high power and very low CHT's. Much easier....and faster, LOP.

[M20Kid]

Thanks for all the tips guys!  I thought I would be doing this procedure last week and now the prop governor is in the shop being overhauled.  I hope this is the last part needing service - my mechanic thinks it should be.  Once the governor is back in place (next week, we hope) it's time to set the high and low fuel pressures and go fly!

I did get the break-in procedure recommended by the engine shop and they say about the same as Walter Atkinson in the post above.

Basically they say the first takeoff is at full power and high airspeed in the climb.  Fly for 30 minutes at 75% power and return to check for leaks or other issues.  Next fly for 1 to 2 hours at "low altitude" (which I assume is to keep the cylinder pressure high) and return again to check things over.  After that they say to fly at 65% to 75% power for the first 50 hours or until oil consumption stabilizes.

I like the idea of taking the airplane higher to get the turbo system pressurized better; those lines could use a shakedown, too.

[jlunseth]

I followed the Continental 25 hour method with mine and it worked fine.  I would strongly recommend against LOP break in of multiple new cylinders in a 231.  Being able to run LOP depends on relatively even fuel flows in all the cylinders, so you are not LOP in four and burning two up in the red box.  The 231 is about as non tuned an induction system as you can find in a non-carb'd Mooney, and hard enough to get to run LOP without dealing with new parts at the same time.  Go LOP after the cylinders are broken in and the injectors are adjusted.  During break in, stay enough ROP to keep CHT's at or under 380.

[M20Kid]

Thanks Jlunseth, that was my thinking too.  I have only had the airplane a few months and have not yet explored LOP operations.  I do have GAMI injectors installed but I haven't done the GAMI check to see if they're set up correctly now.  ROP it is until the rings are well seated and then I can explore the LOP side of life.

[jetdriven]

Quote: M20Kid

Thanks for all the tips guys!  I thought I would be doing this procedure last week and now the prop governor is in the shop being overhauled.  I hope this is the last part needing service - my mechanic thinks it should be.  Once the governor is back in place (next week, we hope) it's time to set the high and low fuel pressures and go fly!

I did get the break-in procedure recommended by the engine shop and they say about the same as Walter Atkinson in the post above.

Basically they say the first takeoff is at full power and high airspeed in the climb.  Fly for 30 minutes at 75% power and return to check for leaks or other issues.  Next fly for 1 to 2 hours at "low altitude" (which I assume is to keep the cylinder pressure high) and return again to check things over.  After that they say to fly at 65% to 75% power for the first 50 hours or until oil consumption stabilizes.

I like the idea of taking the airplane higher to get the turbo system pressurized better; those lines could use a shakedown, too.

[KSMooniac]

And the cooling is even better flying LOP... you want that, especially during break-in!  While the shop is fiddling with the fuel flow setup (make sure they follow the Continental SID and have the equipment to do it properly!) have them test all of your induction system for leaks.  If someone went to the trouble to install GAMIjectors, there is a better than even chance it will run fine LOP.

[Mike A]

What kinds of oil consumption should I expect out of a break-in of a new cylinder? Does it vary flight to flight?

[KSMooniac]

It shouldn't be much for just one cylinder.  Run it high power LOP and keep the CHTs below 400 at all times and you'll probably break it in with just a few hours.  I think I added about a quart after a 4 hour flight while breaking in 4 cylinders.

[aviatoreb]

Here's what always confused me about a LOP break in.

 

Running proper LOP at high power settings requires well balanced injectors - and everything else in the ignition and exhaust system in fine tune.

 

Suppose you are doing a top and your injectors are well balanced for the cylinders coming off, but will they be balanced for the new cylinders?  Or even worse - if you are doing a major overhaul, how will you have balanced injectors for a LOP break in?

[philiplane]

Running at high power LOP during a break in is risky business in this particular engine. Better to go ROP until the rings are seated, and then explore LOP without the burden of possibly ruining one cylinder. You can run LOP on the IO-550N series used in the Bonanza and Cirrus because they are well tuned from the start.

 

On the other hand, as a mechanic, I am more than happy to fix something once it's already gone wrong...

[carusoam]

Cheers to the IO550(n) crowd, used in the latest Ovations...

The advantage of LOP break-in is the lower CHTs and lower FF to match...

The advantage of ROP break-in is the lower CHTs and near flooding conditions where an imbalance won't be noticed as much.

The additional risk in LOP break-in is the imbalanced EGTs caused by imbalanced Fuel Injectors.

Could you consider a mix of ROP and LOP flights?

First hours, ROP to get some experience on the engine and subsystems. GAMI check for FF balance. Then finish off the break-in process at high power LOP.

Full rich is outrageous FF. Low altitude and outrageous fantastic fun. Because that's the recommendation from the manufacturer...!

Since the cylinders are the only thing at risk with a TOH, I would feel more comfortable in making the decision of going LOP after getting a good GAMI test result.

Ring seating may occur within a few hours. Break-in is rumored to take significantly longer. Up to 100 hours?

Doing this with a TC'd engine definitely increases the math and the level of homework.

My thoughts of break-in are only the thoughts of a nonprofessional aviator with no technical aviation background....

Best regards,

-a-

[rob47v]

Someone here mentioned it If their chrome then 75% pwr high manifold if not they will not break in. and have hi oil usage. this could take up to 100hrs, but usually not within the first hour monitor your cht. You will see a quick drop, at that point the rings have seated in and are beginning to bite the cylinders. Keep mineral oil in during breaking since its non detergent it will do its job. If the cylinders are steel the process is the same but take less time way less. Nickle don't need break ins just fly it with mineral for about 10hrs or so. These are the way to go!!!! As an A&P I've seen it all Good luck be safe have fun!!!!!       

[RobertE]

Well, there is a lot of info here so you probably don't need mine. But here goes in brief.

I've done this twice. First time as expected. All was good in a few hours. Second time, same process. It took 100 hours, yes, 100 hours to break in one of the cylinders. Why? Who knows. But I followed the indentical procedure. So before you give up because 25 hours have passed and the plugs still show some oil, don't stop. Keep going.

[aaronk25]

These darn airplane engines, I've come to the realization that some times things don't go as planned and they burn more oil (even newer engines) than they should and at some point you have to decide just to dump oil in and go have fun.