Loss of power after takeoff

[Shadrach]

4 hours ago, teejayevans said:

I think I see what your saying, just for 85% the sea level FF is higher for same MP, it's interesting the app I use for power settings keeps the FF the same for both altitudes, agreeing with the 2000' numbers, as expected.

Exactly! Mass airflow through the engine, MP, and RPM are all the same, so why would it take 2 extra GPH to do it at sea level over 2000'?  The answer is it wouldn't. The POHs before about 1990 were pretty awful.

[ArtVandelay]

7 hours ago, Shadrach said:

Exactly! Mass airflow through the engine, MP, and RPM are all the same, so why would it take 2 extra GPH to do it at sea level over 2000'?  The answer is it wouldn't. The POHs before about 1990 were pretty awful.

I've found they are pretty good when comparing my Econ cruise numbers, I've never used the sealevel charts, I don't cruise much at sea level.

The newer POHs don't have the tables, instead have the horrible graphs..yuk! The tables they do have don't have speeds.

Are there other errors you've found?

 

[Shadrach]

1 hour ago, teejayevans said:

I've found they are pretty good when comparing my Econ cruise numbers, I've never used the sealevel charts, I don't cruise much at sea level.

The newer POHs don't have the tables, instead have the horrible graphs..yuk! The tables they do have don't have speeds.

Are there other errors you've found?

 

Oh mine is full of minor typos. A big error is that cruise charts by altitude are mislabeled and out of order so someone at the factory corrected them with a pencil.  I find the performance numbers are a bit optimistic in terms of cruise but not terribly so, maybe 2-5% in some areas. Climb performance is close, maybe a little optimistic at gross.

Few, if any of us cruise at actual sea level. However, I have departed my 701' airport on days in the winter when the DA -3000' or lower.  If I'm alone and west bound on a windy day, I'll stay low if the bumps aren't too bad. So I have spent a fair amount of time cruising at DAs between sea level and 2000'.  I run WOTRAOLOP whenever I do. It yields impressive speed with fuel burn similar to what my ROP cruise would be in the 7500'.  I've made 300+NM trips without getting above 3000'AGL.

[jlunseth]

I do the same as Ross on windy days headed west, except mine is a 231 so I don't run WOT strictly speaking.  I set the MP at 34" or around there and run LOP.  If I were ROP that would be about a 90% power setting, but LOP I am at 75% (the fuel flow controls HP, not the MP). I get impressive speed that way and the engine seems to like it.  Certainly I do.  I save about 2 GPH.

The only issue I have had with it is one I posted about earlier.  The CHT's are borderline too cold in the dead of winter here in MN.  I repeat, my cylinders can run too cold (at 75% HP).  That's a problem, but I would rather deal with that than have them up in the 400's.

And I agree on the POH's.  

[Shadrach]

21 minutes ago, jlunseth said:

I do the same as Ross on windy days headed west, except mine is a 231 so I don't run WOT strictly speaking.  I set the MP at 34" or around there and run LOP.  If I were ROP that would be about a 90% power setting, but LOP I am at 75% (the fuel flow controls HP, not the MP). I get impressive speed that way and the engine seems to like it.  Certainly I do.  I save about 2 GPH.

The only issue I have had with it is one I posted about earlier.  The CHT's are borderline too cold in the dead of winter here in MN.  I repeat, my cylinders can run too cold (at 75% HP).  That's a problem, but I would rather deal with that than have them up in the 400's.

And I agree on the POH's.  

I've grown accustomed to CHTs in the 280s in the winter. I don't worry about it because the plugs have been fine. 

[marks]

I think many of the suggestions are possible, but for my guess it sounds most like some vaporized fuel in the line.  One time I had a similar experience shortly after I had GAMIjectors installed and my mechanic was right at the field that day, so we took a look and there was a tiny little clog you could barely see with a magnifying glass.  I've heard it's common to pick up a tiny piece of crud that stays in just the wrong place until you take pressure off the throttle and push it in again, then maybe things just pass through.  I doubt the atmospheric guesses.  But everything is a guess.