Break-in prop - hoping to borrow

[jrussl]

With 2300 hours on my O-320 in my SuperCub, it looks to be time to rebuild the engine. As part of the major, I am planning to get some cylinders that are ported, polished, and flow matched fro Lycon.

I plan to have the engine back together sometime early in the new year and am in need of a prop that will better load up the engine than my Borer 8241. Does anyone have a 74-56 prop (or similar) for an 0-320 that I could borrow?

Jeff


Sent from my iPad using SuperCub.Org mobile app

[Rob]

I recently lent one to a friend who converted his exp. T8F from a radial Rotec to an O-320 Too bad you are not closer, we've put some hours on that one and could probably stand to go to the Pawnee prop that will find a permanent home on it. Give me a shout if you don't find a closer solution.

[Steve Pierce]

If you can't find one closer I have one I can ship, have a prop box as well. You will hate it till you put the Borer back on and then you will love the Borer all over again.

[KevinJ]

There’s got to be a pacer around close that you could rob the prop off of for a few hrs. You’ll have $150 in shipping up and back. Offer that to them

[KevinJ]

If the temperature is in the teens or twenties at a low field elevation, wouldn’t you still make enough manifold pressure with a borer to break in the cylinders?

[stewartb]

In my constant speed airplanes the MP is controlled by throttle. I can twist the prop faster or slower and MP stays the same. For break in I want the motor spinning 2500 or 2600 rpm. I'm not sure a coarser prop makes sense unless you're exceeding redline RPM in level flight.

With fixed pitch props I want 2700 RPM at full throttle in level flight. That should be a fine break in prop.

[PerryB]

With a CS prop at a given throttle opening, MP actually does increase somewhat as you pull the prop back, unless you are at or near full throttle. With a fixed prop, I'd want more load than an 82-41 will produce. Cylinder pressure is what you're looking for. RPM by itself does nothing to lap the rings.

[badmdcnman]

Jeff. Just hung a freshly built O320 on my 12 after dropping a valve early October. Both my rebuilder and an extremely qualified pilot friend advised not to breakin with my 82/41 Borer. I’m mounting a 74/55 I had laying around from previous engine on Thursday. Will run 10 hours with that and then reinstall my Borer. Your welcome to use the cruise prop when I am done. I could get it to the Twin Cities if that helps. I would expect to be done with it early December. Not sure if you remember me but we had a good conversation on your trip to the ice caves a few years ago at Randy’s hanger post GMAG. Rod

[skywagon8a]

I’m mounting a 74/55 I had laying around from previous engine on Thursday. Will run 10 hours with that and then reinstall my Borer.

Run it hard until you get a CHT and oil temp drop. The last one I did it took about 18 hours.

[Steve Pierce]

Run it hard until you get a CHT and oil temp drop. The last one I did it took about 18 hours.

What cylinders were you using and what changed after 18 hrs?

[stewartb]

For consideration. In cool temps at altitudes I fly my 75% power RPM would be around 2500. Lycoming says to take off and climb at 100% power, level off and run it at 75% power for an hour, then an hour varying between 65-75% power, then 30 minutes at full power. 100% power is 2700 RPM. Breaking in with a constant speed I used similar RPM targets, adjusted up a little for warmer temperatures. Assuming the Borer doesn't exceed 2700 RPM in level flight, what's the problem?

[Steve Pierce]

For consideration. In cool temps at altitudes I fly my 75% power RPM would be around 2500. Lycoming says to take off and climb at 100% power, level off and run it at 75% power for an hour, then an hour varying between 65-75% power, then 30 minutes at full power. 100% power is 2700 RPM. Breaking in with a constant speed I used similar RPM targets, adjusted up a little for warmer temperatures. Assuming the Borer doesn't exceed 2700 RPM in level flight, what's the problem?

Low manifold pressure. The rings need the higher manifold pressure to push against the cylinder walls and seat. The Borer is working the engine at a lower manifold pressure vs a Sensenich cruise prop. I see 1-1.5 gph less fuel flow with my Borer vs my Sensenich prop.

[stewartb]

Are you making 2700 RPM with the cruise prop?

[Steve Pierce]

I can, and it burns a bunch more fuel.

[stewartb]

Huh. I wonder how so many planes get broken in with Borers and have good results? Everything I've read from Lycoming bases fixed pitch break in power on RPM. They don't discuss pitch. In my CS procedures RPM is to stay high. They don't advise to maintain high MP with reduced RPMs. I've heard the cruise prop discussion several times. It just doesn't add up.

[PerryB]

It CAN be broken in successfully with the 82-41 but you better keep it at a solid 2600 in cruise to achieve a decent MP number. Manifold pressure is what it's about during break in. There's no added benefit to having to run the engine near redline to achieve it. If anything, it's just going to run hotter for no reason. The Lycoming fixed pitch procedures are based on RPM because MP is not independently controllable BUT, it's assumed you'll be running an OEM/cruise type prop. Even the factory "climb" prop for the Supercub/150 (52" I think) produces more MP than a 41 Borer at a given RPM. A typical 150/320 with an 82-41 cruising at 2400 is probably making 20" at best. It's like driving around in first gear. You need load to seat the rings. RPM does not equal load, manifold pressure does. To get that you either run it to the wall and ignore the tach, or hang a coarser prop on it and make load down at a more reasonable RPM. I'm going to be on here one of these days looking for a fatter prop too. I want a LyCon build REAL bad.

[Steve Pierce]

When dealing with the cost if it doesn't break in correctly I go with everything I know and have learned to hope everything breaks in correctly. ECI says you can use their 20w50 X/C engine oil for break in but I still choose to use Mineral Oil. There are some old threads here on the use of a shorter cruise type prop for break in vs. the Borer.

[jrussl]

Thanks for all the great advice and offers of loaner props. I continue to be amazed by this community.

A lot of the break-in info shared here is consistent with what others have shared with me that is to break-in the engine properly, I need both high RPM and MP. I am currently a little underpropped with my Borer 8241 in that I turn about 2830 RPM flat out in level flight. I haven't re-pitched because I really like the take-off performance. Hopefully, with a bit of Lycon magic, I will be even more underpropped after the re-build. I also currently see around 19"-20" MP (CGR-30P) turning 2500 RPM with my 8241 and would like to see this higher for break-in.

Rod, I sure do remember our conversation about the ice caves. Hopefully we'll have good enough ice this year to open them up. It's hard to believe that they haven't been open since 2015. You also happen to be the closest offer for a loaner prop. Thank you. I may take you up on it and will get back with you by mid December.

Thanks again, everyone!

Jeff

[G44]

Jeff, after overhaul and the mods that are being done to make your engine stronger the 41 pitch will be waaaayyyy too flat. After break in with a loaner prop I would repitch your prop to 43 or 44 pitch. Your take off will still be good and your cruise will improve. I repitched my 42 to a 44 years ago on a stock 150, I did not notice much if any loss of take off performance but I did notice the better cruise speed or the lower fuel flow at the same speed.

Kurt

[skywagon8a]

What cylinders were you using and what changed after 18 hrs?

It's been a while Steve, I believe they were Nichrome on the TSIO-520 in my 185. At the 18 hour mark the CHT and the oil temp visibly dropped. I took it on a trip to the Bahamas. Half way home I just happened to be looking at the temperature gauges at the time it happened.

[BC12D-4-85]

Now with electronic panels that record engine parameters it might be easy to note the break-in points.

Gary

[stewartb]

My cylinders were broken in in the 1 hour on Lycoming's test stand. The only concern I had was oil consumption. That took just a few hours but it took a few extra hours to recognize it. Oil consumption is higher at high power/high RPMs. Deciding when to dial it back and fly it normally is subjective.

[mike mcs repair]

Hmmmm. All the engines were broken in with borer props that I know of.... never heard of any problems..... all this stuff been done fine for decades, until you get on the internet, and it says that won’t work.... strange.


Sent from my iPhone using SuperCub.Org

[Steve Pierce]

It's been a while Steve, I believe they were Nichrome on the TSIO-520 in my 185. At the 18 hour mark the CHT and the oil temp visibly dropped. I took it on a trip to the Bahamas. Half way home I just happened to be looking at the temperature gauges at the time it happened.

Had very good luck with new cylinders breaking in in a few hours. My Dad was in engine manufacturing and said it is the new boring processes.

[Steve Pierce]

My cylinders were broken in in the 1 hour on Lycoming's test stand. The only concern I had was oil consumption. That took just a few hours but it took a few extra hours to recognize it. Oil consumption is higher at high power/high RPMs. Deciding when to dial it back and fly it normally is subjective.

I always thought the drop in oil consumption was a sign it was broken in.

[Steve Pierce]

Hmmmm. All the engines were broken in with borer props that I know of.... never heard of any problems..... all this stuff been done fine for decades, until you get on the internet, and it says that won’t work.... strange.


Sent from my iPhone using SuperCub.Org

Probably the magic air in Alaska. Actually I know of a couple, up there that didn't break in and had to come off and be honed. I'd rather run the recommended prop and not need it than have to pull cylinders for rehone. I have built way to many engines and feel like I am on the hook for way to long so I do everything I know to eliminate any possible issues.

[Steve Pierce]

Hmmmm. All the engines were broken in with borer props that I know of.... never heard of any problems..... all this stuff been done fine for decades, until you get on the internet, and it says that won’t work.... strange.


Sent from my iPhone using SuperCub.Org

Oh yea, got nothing to do with the Internet. Came from 2 engine builders who have been building g them for 40 plus years each. I tend to listen when they tell me things.

[mike mcs repair]

. I have built way to many engines and feel like I am on the hook for way to long so I do everything I know to eliminate any possible issues.

And that’s what I tell the customers, talk to the overhauler and do what they want(and everyone has different directions/opinions)because they are the ones on the hook. We have many specialized engine shops here locally, and I farm that out to them. Not something I’m interested in doing for others. only did it for our own airtaxi plane.


Sent from my iPhone using SuperCub.Org mobile app

[stewartb]

I always thought the drop in oil consumption was a sign it was broken in.

Break-in is when cylinder temps normalize and oil consumption stabilizes. In my last 3 engine break-ins I knew the cylinder temps were good in the first hour. It takes several flights and several hours to establish oil consumption trends. Nobody wants to ease up on $40K motor too soon and leave some performance on the table, right?

[Steve Pierce]

I was curious how you knew Lycoming had it broken in on the test cell, CHT makes sense. They seem to break in now in the first hour or so but I still run them per Lycoming s break in for about 10 hrs or so. Kicked one out the door Friday and he called today with 11.5 hrs, good temps and not using oil. I breathed easier. When my Dad was an engineer at Cummins they monitored crankcase pressure on the test cell and they could tell when the rings seat by monitoring the pressure. They had a few cases where the rings didn't seat and they shot Bonami through the intake and it would break the glazed cylinder walls and seat the rings.

[stewartb]

My Lycoming manual says to run 65-75% power for 50 hours or until oil consumption stabilizes. If I use a quart in 4 hours now how do I know it won't get better if I continue to run it hard?

Re: cylinder pressure and the notion that a cruise prop is beneficial. Does it matter if it's a 150hp or 160hp engine? 7.5-1 vs 8.5-1. What does that do to cylinder pressure? What about guys running 10-1? Lycoming doesn't differentiate in any publications I've found.

Why do they imply ashless dispersent oil is bad for a normally aspirated engine at break-in when they require it for turbocharged engine break-in?

[Steve Pierce]

Break an engine in at high power. Same reason an automotive engine needs to be loaded with the transmission. High pressure expands the rings allowing them to seat, otherwise you get a film of oil between the ring and the cylinder wall and it glazes over the cross hatch and will never break in. Turbo charged engines create more pressure and need AD oil to break in with the extra pressure.

I have installed 11.5 to 1 pistons/cylinders in an engine going to the world aerobatic contest along with several sets of 10.5 to 1s. The engine builder that provided the cylinders had us break them all in like everything else but was adamant that we monitor temps.

I like to know why but sometimes the science is over my head and just doing what an expert tells me works and I can spend my time worrying about something else.

[behindpropellers]

Jeff,

I have a prop you could borrow. In Cleveland but could be coaxed to meet you in Michgan. Pretty sure you have my email.


Tim

[jrussl]

Jeff,

I have a prop you could borrow. In Cleveland but could be coaxed to meet you in Michgan. Pretty sure you have my email.


Tim

Thanks, Tim. I appreciate the offer. I actually just got a PM from another dot orger that is very near to me and he has offered either a Borer 8244 or a 7458 cruise prop for me to use.

Thanks everyone for the offers and all the advice.

Jeff

[skywagon8a]

...... a 7458 cruise prop for me to use.

Use this one. Throttle to the stop and go. I had a new 172 picked up in Wichita by a friend. I told him to push the throttle to the stop and fly it home. Only pull the throttle back when the rpm wanted to exceed the red line. The flight started with the throttle hard against the stop, by the time it arrived home it was well back from the stop. That engine always ran beautifully, until a jerk wrecked the airplane. I believe in the "run it hard" break in.

[windy]

Glad to hear your engine will get spruced up during the winter, outside of the big flying season. You’ll be raring to go!

You could save some Avgas money by skipping the port & polish. I had it done on my last O-360 overhaul, but not on the current one. I can’t tell the difference. The aircraft weight makes more of a difference, IMHO.

I hope your overhaul goes smoothly. Just be sure to get a mechanic that knows their a$$ from a hole in the ground. I wish I had!


Sent from my iPhone using SuperCub.Org