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Break-in prop - hoping to borrow

jrussl

jrussl

BENEFACTOR
Madison, WI
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
 
I recently lent one to a friend who converted his exp. T8F from a radial Rotec to an O-320 :-x 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.
 
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. ;)
 
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
 
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?
 
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.
 
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.
 
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
 
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?
 
stewartb said:
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?
Click to expand...
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.
 
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.
 
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.
 
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.
 
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
 
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
 
Steve Pierce said:
What cylinders were you using and what changed after 18 hrs?
Click to expand...
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.
 
Now with electronic panels that record engine parameters it might be easy to note the break-in points.

Gary
 
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.
 
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
 
skywagon8a said:
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.
Click to expand...
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.
 
stewartb said:
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.
Click to expand...
I always thought the drop in oil consumption was a sign it was broken in.
 
mike mcs repair said:
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
Click to expand...
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.
 
mike mcs repair said:
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
Click to expand...

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.
 
Steve Pierce said:
. 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.
Click to expand...


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
 
Steve Pierce said:
I always thought the drop in oil consumption was a sign it was broken in.
Click to expand...

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?
 
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.
 
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