Where should my RPM Max out?

[wiegerket]

I have a PA-22-160. The prop is a Sensenich M74DM. Max RPM while parked is about 2250-2300. In Cruise 2500 doing about 110Kt. Are these normal values?

[bvmbandit]

I have a PA-22-160. The prop is a Sensenich M74DM. Max RPM while parked is about 2250-2300. In Cruise 2500 doing about 110Kt. Are these normal values?

Cruise or climb prop? What pitch prop?

- Vern

[wiegerket]

is there a cruise and climb variant of the M74DM?

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[CamTom12]

There's different prop pitches. Mine is pitched at 60" and is squarely in the "cruise" category.

[Gilbert Pierce]

74DM6-58” is a climb prop. Extreme cruise props are 61”

[dgapilot]

Years ago I had a PA-22-160 that I used for banner towing. When I got the airplane it had a 60” pitch prop. Flew fine but didn’t tow very well. Had it repitched to 53”, and it climbed like no tomorrow. Didn’t cruise worth a damn though! All that said, the TCDS provides limits for static RPM. For the PA-22-160 with an M74DM, your limits are not over 2450, and not under 2250. Diameter limits are not over 74” and not under 72” since you indicate that static you are 2250 -2300, that would indicate either you have a cruise prop (60 or 61” pitch) or a sick engine. Based on the owners manual, 75% power sea level should be 125 and 75% at 7000’ should be 134 mph. 75% at sea level is about 2475 RPM based on the O-320 owners manual. I’m guessing 75% at 7000’ is going to be 2700 rpm (don’t have the time to follow all those lines on the chart, and you didn’t say what your MAP is) You are claiming 110 kts ~126.5 mph so it sounds like you are doing exactly what the book says you should be doing.


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[mongoose09]

On my Pa-22-150 with a 74DM6-58 my static RPM is 2400.