IO-360 at 2700 rpm

[zaitcev]

Suppose that for some circumstances, I decided to go all out[1]. Is this safe for engine's long-term health?

[1] I am looking at a flight that at my normal speed takes 9 hours, which means it needs to be split into 2 days. If I could get just a little bit more speed, I could cover it in a day, at the expense of the greater fuel burn. And yes, the noise requires double-plugging with cotton balls under the headset, that's a given.

[gsxrpilot]

I don't believe 2700 is a problem for the engine. But what you're really talking about is running at max power for an extended period of time. Again, probably not an issue as long as you're rich enough. And by that I mean 100 degrees or more rich of peak.

But burning that much fuel means that you'll likely pay for that extra speed with an extra fuel stop or more which will kill your time A to B.  

The best way to get more speed out of these Mooneys is not to go faster... it's to burn less gas and skip a fuel stop. I think you might be better off at Carson's speed and deep LOP.

[zaitcev]

In my case, going longer presents a problem as I cannot stay in the plane for too long: everything hurts, I get restless. I never do legs that are longer than 3 hours. The max-range 8 hours day for me is taking off early, then do 4 2-hour segments. At the end of the last one it's already close to 5 p.m. when FBOs start to shut down. If I get off this rhythm, I end covering less. So, an attempt to skip a fuel stop is going to be self-defeatng. I only do it for trips under 400 nm, where I can basically do it in one go and then keel over for the rest of the day.

Edited August 30, 2018 by zaitcev

[ArtVandelay]

To me, the engine noise seems a lot less at 2600 vs 2700, I even do takeoffs at 2650, just to be nice to the neighbors.
What’s the problem? if the seats are uncomfortable, you can redo them with new foam, leather. My personal best is 11.9 hrs with 1 stop, but I’m not wanting to do that again.

[gsxrpilot]

Ah... so you're basically just trying to get further in a two hour flight window. In that case, yes, just figure out where the best power setting is for you. We'll assume WOT, 150 degrees ROP, and likely 2700 RPM.

[jaylw314]

50 minutes ago, zaitcev said:

Suppose that for some circumstances, I decided to go all out[1]. Is this safe for engine's long-term health?

[1] I am looking at a flight that at my normal speed takes 9 hours, which means it needs to be split into 2 days. If I could get just a little bit more speed, I could cover it in a day, at the expense of the greater fuel burn. And yes, the noise requires double-plugging with cotton balls under the headset, that's a given.

2700 RPM is exactly 3.85% faster than 2600, so you'll wear out your motor that much faster.  I don't think that's worth worrying about, as long as you aren't making so much power the engine gets too hot.  Above 8000' or so, that's not really an issue.  And the higher you go the less bothersome the engine noise is.

[ArtVandelay]

2700 RPM is exactly 3.85% faster than 2600, so you'll wear out your motor that much faster. 

You are assuming the wear and tear is linear, I think that’s a bad assumption.
That said, engine RPM is only 1 factor when considering engine wear and tear.

[Niko182]

52 minutes ago, jaylw314 said:

2700 RPM is exactly 3.85% faster than 2600, so you'll wear out your motor that much faster.  I don't think that's worth worrying about, as long as you aren't making so much power the engine gets too hot.  Above 8000' or so, that's not really an issue.  And the higher you go the less bothersome the engine noise is.

since its a constant speed prop, the effect strongly varies on MP, RPM, CHT Temps, Fuel flow, and many other things. if you took your m20J to FL150, you could probably run it at full RPM and WOT and it would still probably make TBO just fine if you kept the fuel flows decent. Do the same thing at 2000FT MSL, and you'll kill your engine pretty quickly.

[jaylw314]

9 minutes ago, Niko182 said:

since its a constant speed prop, the effect strongly varies on MP, RPM, CHT Temps, Fuel flow, and many other things. if you took your m20J to FL150, you could probably run it at full RPM and WOT and it would still probably make TBO just fine if you kept the fuel flows decent. Do the same thing at 2000FT MSL, and you'll kill your engine pretty quickly.

I'm guessing WOT and full RPM at 8000' would be fine, since you can only make about 70% power anyway.  Lycoming expects you to make TBO if run below 70% regardless of how you lean.  Whether you believe that or not...  OTOH, I suppose it could affect the life of your cylinders, but not TBO

[jaylw314]

30 minutes ago, teejayevans said:

You are assuming the wear and tear is linear, I think that’s a bad assumption.
That said, engine RPM is only 1 factor when considering engine wear and tear.

 

I assume wear and tear is NOT linear with RPM.  I think it is not directly related at all.  I recall studies suggesting that the large majority of engine wear is from normal starts, not cruise operation, and the engine bottom end is not exposed to the effect of high CHT's anyway

[Herlihy Brother]

• One data point: I have been commuting from Calif to Texas for 13 years in a '64 e with the io360a1a.  Usually 12k' eastbound and 9500' west bound, and usually WOT and 2700.   8 hours eastbound with one fuel stop and 9-10 hours westbound with two fuel stops. I lean to between 100 degrees rich to sometimes peak egt.  Most times I lean for for max airspeed/best power.  My engine was overhauled in 1986 and has 2800 hours smoh, 6000 total time on it.. Compressions are 79 on all 4. I change the oil every 25, filter every 50. In that time, one cylinder had a "tuliped" exhaust valve that was replaced at 1400 smoh. It was not burnt or anything, so most likely a defective valve.  If you don't have the a1a engine then you may have counterweights, and I have seen those cause problems in other 360's going over tbo.  2700 is relatively low rpm designed for longevity afaik. I have heard that racers spin these up to 3200 routinely.

[carusoam]

One thing to consider...

If two hours is your comfort limit...

taking out as much vibration as possible might be a good idea.

Getting the prop dynamically balanced at the rpm you intend to cruise at may make some sense....

Best regards,

-a-