Nearing TBO, Lycoming or Penn Yann?

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Looking for thoughts on Lycoming or Penn Yann for the overhaul of a Lycoming O540 on a plane that I fly and help maintain

Current engine is a Lycoming factory overhaul that reached TBO with two cylinders replaced at ~1,700 and ~1,800 hours and no other major issues.

We are tentatively going w/ Penn Yann. Reasons:
1) Penn Yann has a long and very good reputation in the industry
2) Lycoming require a ~20K core deposit in advance and (we hear) are known to frequently reject cores,
3) After sale service- We have heard of several recent cases where Lycoming’s support to the individual owner is less than adequate while Penn Yann has a much better reputation...at least among the local A&P's we talked to,
4) Cost, based on list prices, Lycoming is at least ~$10k greater (upgraded roller cam, engine), initial prices though, further work would close that gap.

The downside is that Penn Yann is not able to offer the updated roller camshaft available on new Lycomings. The roller cam is a huge advance and much better that what is in the plane now but for our use, I don’t know if I can justify the cost to upgrade.

I know a few folks here have done engines over the past few years. Appreciate the thoughts.
 
I wouldn't be concerned about using a remanufactured engine from either Lycoming or Penn Yann, they are both reputable engine suppliers. I wouldn't hesitate to fly an airplane that has an engine in it from either of them. You have to make the determination on the cost of the engine and how much you want to spend before making the choice of suppliers.
 
I am not sure it matters all that much who performs an overhaul. A Lycoming factory overhaul and a field overhaul can be functionally identical. The very same parts are generally involved. Such as new Lycoming brand cylinders and so on. One, could hire a local A+P, purchase all the same new parts (as Lyc uses) right from Lycoming and the two engines would be exact matches.

However, Lycoming roller cam engines are very smooth and more reliable in various ways. "IF" you are choosing between a flat tappet engine and a roller cam engine, people generally have better results with the roller cam engine. The cases are less prone to cracking, the engines are slightly more efficient, and pilots universally report smoother operation.

My Lycoming engines are currently all flat tappet engines. I use CamGuard in an attempt to prolong camshaft life. We've had a number of camshaft issues over the years. Mostly due to corrosion. I even installed a "drilled camshaft" in an attempt at reducing cam wear and preventing future problems. I really do not have objective data as to whether it works or not. The roller cam is the proper solution.

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Another note, I'm not afraid of reports of poor customer service on Lyc engines. If you have a major problem (unlikely) , it's quite possible the problem will occur somewhere other than your home airport. And you will be the one responsible for scheduling and managing the repair. In such a case, why worry about what might happen? It's impossible to predict.
 
I know I'm uninformed when it comes to airplanes, but why would it matter if the engine was roller cammed or flat tappet? Why have they not figured the cam profile out on the flat tappet version to deal with smoothness? Why is longevity an issue- so much that some are adding other products to the oil? I would think that a properly spec'ed and approved lube would be sufficient? It seems that with the extreme cost and amount of hoops a person has to jump through to get an engine off the ground, the darn thing shouldn't be so picky...

Sorry for all the questions, but I'd like to learn a little bit about what's going on in these very interesting engines.
 
Originally Posted By: The_Eric
I know I'm uninformed when it comes to airplanes, but why would it matter if the engine was roller cammed or flat tappet? Why have they not figured the cam profile out on the flat tappet version to deal with smoothness? Why is longevity an issue- so much that some are adding other products to the oil? I would think that a properly spec'ed and approved lube would be sufficient? It seems that with the extreme cost and amount of hoops a person has to jump through to get an engine off the ground, the darn thing shouldn't be so picky...

Sorry for all the questions, but I'd like to learn a little bit about what's going on in these very interesting engines.


The Lycoming camshaft is located above the crankshaft. It is not immersed in oil, and does not get lubricated with cold engine oil until about 1200 RPM. Since these things idle around 600RPM, dry startup might be a bit of an issue. But, worse than that, the cam location is ideal for condensation to form. Rust is the real problem here. It forms quickly and rapid wear results. See my above picture.

There is much going on in aircraft engines. The very high cyclic loads require different design philosophy. Hence little things like "screw on" cylinder heads and very long studs holding the cylinders down.

The cylinders are air cooled, have quite a bit of clearance and the piston rings don't seal like a modern car. These engines consume oil. That oil can't leave deposits in the combustion chamber. So, it does not contain ZDDP. This might also contribute to shorter camshaft life.

The roller cam versions don't have the same issues. If a little corrosion forms, it's not a catastrophe. Plus the roller cam cases have been strengthened/re-engineered to avoid the problems that the older cases suffered. (remember the very high cyclic loads)

We love to make fun of the lowly "lycoming" aircraft engine, with 360 cubic inches and "only" 200HP. But, remember that HP is produced at 2700 RPM, direct drive to the prop. Those are very high cylinder pressures to achieve that level of power. Couple that with a 5.25 inch bore, and there are huge stresses involved.

Interestingly, the IO-360 in my Cessna achieves a BSFC in cruise of 0.38 LB/HR/HP. Those are excellent numbers, considering it's producing close to as much power as it can, at cruise altitude. Full throttle, 2500-2600RPM (remember redline is 2700)

As far as engine "smoothness" goes, that's a rather subjective thing. It's not due to a different valve lift profile. I believe it's related to lower friction levels.
 
Thanks all. We agreed on Penn Yann, we just could not justify the extra cost of the roller cam given the flying we do.

Great cam picture. Saw one just like that on a Tomahawk
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I used to fly...and really enjoyed.
 
In regards to the Penn Yan overhaul, what has deterred you from a field overhaul with new Titan cylinders?

Cujet: In consideration of the oiling issue at low rpm have you considered a lower viscosity oil? I've been using Aeroshell W-65 for 15 years. I have beautiful UOA's. Have an IO-360 in a T-41B and a pair of TSIO-360's in a Skymaster. Fuel flow LOP in the T-41 ranges from 6.8-7.2gph. Great motors.

Dave
 
Originally Posted By: DrDave
In regards to the Penn Yan overhaul, what has deterred you from a field overhaul with new Titan cylinders?

Cujet: In consideration of the oiling issue at low rpm have you considered a lower viscosity oil? I've been using Aeroshell W-65 for 15 years. I have beautiful UOA's. Have an IO-360 in a T-41B and a pair of TSIO-360's in a Skymaster. Fuel flow LOP in the T-41 ranges from 6.8-7.2gph. Great motors.

Dave


My airplane now has a "Centrilube" camshaft. It has the drilled holes to promote oiling at any RPM. There is some data that is favorable too.

I now use Aeroshell 15W-50, about the thinnest oil I can run. My UOA's come out just fine. But I also fly my airplane regularly to keep corrosion at bay.

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Just curious, why is a 50wt oil the lightest you can run? I'm assuming we are talking about fully warmed up operation.

Dave
 
Originally Posted By: DrDave
Just curious, why is a 50wt oil the lightest you can run? I'm assuming we are talking about fully warmed up operation.

Dave


That's a 15W oil. It's simply performs like a 50 at 100 degrees C.

The Lycoming oiling issue is a start up issue. 15W is thin enough. I'm not sure of any aviation oils that are thinner, or that I'd want to use them.
 
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