[kentb]

My constant speed IO320 powered RV9A max speed is reduced with alt.
At takeoff (179 ft) FULL in on everything my RPM is 2720. By the time I reach 8000 ft and level off (still FULL in on all controls) I am only turning 2670.
Is this to be expected?
Should I adjust something?

I don't normally run at full RPM except takeoff, but I was doing some speed testing and noticed this.

Kent

 

[Mel]

One of two possibilities...

You're either running out of power. (Doubtful)
Or the fine pitch stop on your prop or is adjusted improperly.

 

[Walt]

You're either running out of power. (Doubtful)
Or the fine pitch stop on your prop or is adjusted improperly.

If your fine pitch stop was misadjusted (had the blades at to much of an angle) you would not make 2720 RPM on TO.

I would try pointing the nose down a bit to gain a little airspeed when you at 8K ft, if the RPM comes up then you probably are running out of juice.

 

[scsmith]

somewhat normal

I find that as the engine oil warms up, the max RPM drops a little. On my WW 200RV prop, first takeoff of the day will generate 2680. If I'm shooting circuits, by the 3rd takeoff, I'm getting 2640 or so. Kevin Horton reported similar on his blog, so I think this is somewhat normal.

 

[gasman]

By the time I reach 8000 ft and level off (still FULL in on all controls) I am only turning 2670.

Should I adjust something?

Yes, the mixture should be adjusted. The motor is running rich and causing a decrease in power.

 

[kentb]

whoops.

Yes, the mixture should be adjusted. The motor is running rich and causing a decrease in power.

Your right Gasman. I had pulled mixture to get 100 ROP.

Kent