Lean of Peak: Cessna 400 w/TSIO550C

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snp1973

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Steve
Regarding this engine installation...

The AFM seems to indicate that LOP should only occur at power settings of 65% or less.

Some I know operate LOP above that AFM recommendation based on info from TCM. What I'd like to do is put my hands on a document or guidance that "blesses" this procedure. Can anyone be of assistance?

Thanks.
 
Hey Ted... Someone has been spiking the Kool-Aid again...
 
snp1973 said:
Regarding this engine installation...

The AFM seems to indicate that LOP should only occur at power settings of 65% or less.

Some I know operate LOP above that AFM recommendation based on info from TCM. What I'd like to do is put my hands on a document or guidance that "blesses" this procedure. Can anyone be of assistance?

Thanks.
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I don't think you're going to find that info from TCM. You're going to have to search for the "Pelican's Perch" articles on AvWeb and read through a few LoP threads here and on the AOPA forums as well as see what sort of promo material you can find on LoP ops from GAMI and then draw your own conclusions on what is safe operation for your engine.
 
tonycondon said:
I don't think you're going to find that info from TCM. You're going to have to search for the "Pelican's Perch" articles on AvWeb and read through a few LoP threads here and on the AOPA forums as well as see what sort of promo material you can find on LoP ops from GAMI and then draw your own conclusions on what is safe operation for your engine.
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+1. Read up on John Deakin's column "Pelican's Perch" regarding LoP operations and "staying outside the red box." We ran the Bonanza (TCM IO-550) LOP and it loved it. We run the mooney (TCM TSIO-360) LOP and it also seems to enjoy it while saving some extra gas. YMMV. Opinions vary widely on this topic.
 
Also bear in mind that most AFM power tables are based on best power (or best economy) mixture settings, so you if you are running LOP, you are actually developing less power than the table suggests. Unfortunately there isn't a good way of determining what power you are developing, other than by airspeed comparison. If you were flying a fixed pitch prop, it would simply be a function of RPM.

Personally I just run it LOP under 65% by the table and live with it.
 
Sac Arrow said:
Also bear in mind that most AFM power tables are based on best power (or best economy) mixture settings, so you if you are running LOP, you are actually developing less power than the table suggests. Unfortunately there isn't a good way of determining what power you are developing, other than by airspeed comparison. If you were flying a fixed pitch prop, it would simply be a function of RPM.

Personally I just run it LOP under 65% by the table and live with it.
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Actually, if you have an accurate fuel flow indication you can easily determine your HP when LOP. For a "high" compression engine (8.5-8.6:1) the HP will be very close to 14.9* gph. For "low" compression engines the factor is 13.5 IIRC.
 
snp1973 said:
Regarding this engine installation...

The AFM seems to indicate that LOP should only occur at power settings of 65% or less.

Some I know operate LOP above that AFM recommendation based on info from TCM. What I'd like to do is put my hands on a document or guidance that "blesses" this procedure. Can anyone be of assistance?

Thanks.
Click to expand...
What Lance said.

Also, the recommendation to run LOP only _below_ 65% is nonsensical. There's no technical reason whatsoever to restrict LOP ops to below 65%. You need to be more careful with ROP at high power settings than if you were LOP.

Don't believe TCM or Lycoming either as their published information on engine operation is often incorrect. As someone else said, follow the LIMITATIONS part of the POH. Everything else is just someone's opinion on how to fly the airplane.

This discussion was over 5 years ago in the GA word and 30 years ago in the automotive world. Too bad some people haven't gotten the memo....which I'm sure you'll see in some of the following responses :)
 
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sba55 said:
What Lance said.

Also, the recommendation to run LOP only _below_ 65% is nonsensical. There's no technical reason whatsoever to restrict LOP ops to below 65%. You need to be more careful with ROP at high power settings than if you were LOP.

Don't believe TCM or Lycoming either as their published information on engine operation is often incorrect. As someone else said, follow the LIMITATIONS part of the POH. Everything else is just someone's opinion on how to fly the airplane.

This discussion was over 5 years ago in the GA word and 30 years ago in the automotive world. Too bad some people haven't gotten the memo....which I'm sure you'll see in some of the following responses :)
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And you, of course, know all about engine operation from your thousands of hours of time flying your LearBaron, and years of running engines on dynos, not to mention years in the auto industry doing engine calibrations. Wait a second, you haven't actually done any of those, so you make broad statements that don't give nearly enough detail for someone to actually gain anything useful from, but enough info for them to cause damage. :rolleyes2:

OP: Best thing you can do is try to educate yourself from as many reputable sources as you can, talk to some people who've run engines like yours in planes like yours with success, and figure out what you want to do. You've gotten some good advice so far, other than the above.
 
Because of the derated engine in the Columbia/Cessna 400, it's approved for continuous operation at 85% power. I ran my '05 COL4 at 75% - 80% power about 100 degrees LOP for several hundred hours and had no problem with it whatsoever. I got about 190+ kts on 18.5 g/h running it that way and it never skipped a beat. I know that doesn't answer your question for some documentation but I based my operation of the plane on the way the Columbia factory taught me to run it which they claimed was based upon the recommendations of the Advanced Pilot Seminar folks.
 
PittsDriver said:
Because of the derated engine in the Columbia/Cessna 400, it's approved for continuous operation at 85% power. I ran my '05 COL4 at 75% - 80% power about 100 degrees LOP for several hundred hours and had no problem with it whatsoever. I got about 190+ kts on 18.5 g/h running it that way and it never skipped a beat. I know that doesn't answer your question for some documentation but I based my operation of the plane on the way the Columbia factory taught me to run it which they claimed was based upon the recommendations of the Advanced Pilot Seminar folks.
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See, that's useful information.
 
Ted DuPuis said:
See, that's useful information.
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I should have added that I was told by the factory chief instructor that they'd been given a verbal OK from Conti to teach it that way but that they'd seen no formal written word about it. That was all back in '06 and I never looked back to verify what Conti had to say about it. It worked fine for me though on the Platinum engine that I had in mine.
 
gismo said:
Actually, if you have an accurate fuel flow indication you can easily determine your HP when LOP. For a "high" compression engine (8.5-8.6:1) the HP will be very close to 14.9* gph. For "low" compression engines the factor is 13.5 IIRC.
Click to expand...

Yes, what I meant was there was no good direct way to measure HP. That gives a fairly good approximation.
 
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