Engine rpm

Went flying today and on climb out I noticed that my rpm was only 2150 but my manifold was 29" ?
I have an o-320 with a fixed pitch senseninch prop.
Do these numbers look right?
It's a relatively new plane to me, so I'm just asking.
Climb seemed rather sluggish but I had full fuel and 2 people aboard, and it was 80 degrees.

You apparently have a cruise pitched prop, which explains both the low RPM and high MP at takeoff. I would say that 2150 RPM is on the low side of normal, so it is possible that your prop is overpitched.

How many RPM does the engine turn at full throttle in level flight? That's the other measure of pitch. Most would suggest a "flat out" max RPM to be 2700, possibly a little higher. If you can't achieve that, your prop is definitely over pitched unless you have the metal Sensenich prop with its 2600 rpm limit.

By the way, what airframe and which Sensenich prop do you have (wood, metal, composite)?

Those numbers match what I get with my O-360 powered -9.

The difference is that I will climb slightly better due to the more powerful engine.

Cruise, as stated above, should put you on the redline at 8000' DA, which should be right around 75% power with full throttle and leaned for best power.

Taking off is where CS props really shine.

I have a 9A with a metal fixed pitch.
Don't think I can get close to 2700 rpm more like 2400 rpm in cruise at 3000 ft
I plan to check the model number when I get back out the hanger.

2600 rpm limit

N941WR said:

Those numbers match what I get with my O-360 powered -9.

The difference is that I will climb slightly better due to the more powerful engine.

Cruise, as stated above, should put you on the redline at 8000' DA, which should be right around 75% power with full throttle and leaned for best power.

Taking off is where CS props really shine.

Click to expand...

Careful with redline rpm testing... from the Sensenich web site for the 70CM prop...

This particular propeller does have a 2600 rpm placard. Although this placard limits the maximum rpm of the propeller to 2600, the performance of this propeller in climb, cruise and top speed is not compromised.

az_gila said:

Careful with redline rpm testing... from the Sensenich web site for the 70CM prop...

This particular propeller does have a 2600 rpm placard. Although this placard limits the maximum rpm of the propeller to 2600, the performance of this propeller in climb, cruise and top speed is not compromised.

Click to expand...

My Catto prop has no such RPM restriction.

N941WR said:

My Catto prop has no such RPM restriction.

Click to expand...

Yes, but the OP says he has a metal Sensenich with an O-320...

RPM

Guido, I have the Sensenich FP metal prop with 160 hp 0320D2B on my 6A. I recently checked static RPM at 70' MSL on a hot June day in Baton Rouge. I topped out at 2200 RPM with 29" MP. I leaned the engine a little to get more power. I think the engine/prop combination we have just doesn't climb that well compared to other RVs. I can easily exceed 2500 RPM in cruise though. I guess different airframes may have a lot to do with that. Seems like during takeoff and initial climb my RPMs are about the same as static RPM. John