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RV-6A max rpm

pylotttt

Active Member
I just bought an RV-6A with an o320 160hp Lycoming and a Sensenich 70CM7S9-0 (79) PITCH PROP.
What should the max rpm be in cruise?
POH says run at 2200 to 2500 rpm and do not exceed 2600 rpm. What are most people seeing at full throttle in cruise?

Thanks
 
I just bought an RV-6A with an o320 160hp Lycoming and a Sensenich 70CM7S9-0 (79) PITCH PROP.
What should the max rpm be in cruise?
POH says run at 2200 to 2500 rpm and do not exceed 2600 rpm. What are most people seeing at full throttle in cruise?

Thanks

Full throttle rpm will depend on altitude but please be advised the 2600 rpm limit for the prop is very real. There are blade harmonics above 2600 that Sensenich wasn't able to eliminate that could be destructive. I suspect your plane is capable of exceeding 2600 with the 79" pitch prop. But don't do it.

Running close to 2600 in cruise can be a problem in thermals if on autopilot or trying to maintain an altitude. As you fly down the backside of a thermal rpm can increase very quickly. Good practice is to leave a little margin so you won't exceed redline.

For background, I fly a 1999 RV-6 with O-320 and ~80" metal Sensenich. Enjoy your new ride!
 
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One more note...the Sensenich is a good prop. 79" is the correct pitch for your -6A and yields a good combination of climb and cruise.

I've never been tempted to flirt with the 2600 limit because fuel burn goes up with little increase in cruise speed when pushed that hard. I find 2400 (below 6000' DA) to be an excellent compromise of speed and fuel burn...about 155kts true with 7.5 gal/hr. Flying five knots faster costs over a gal/hr more.
 
No manifold gauge. I am only seeing 2500 rpm max. I'm not sure if it is a reading error. I need to get an optical tach to test it.
My cruise speed is good, at 4500' doing a 2 way test I got 207mph and 178mph, but If it really isn't making 2600 I want to adjust it for better takeoff/ high density altitude performance.
 
Your takeoff power will be limited by the RPM it can do. Mine was in the 2200 range on the takeoff roll. It could be re-pitched for more TO power, but you'd be pushing the 2600 RPM limit more of the time in cruise and right now when you lower the nose. I would usually cruise climb. 140kt groundspeed would get me ~700 or 800 fpm with better cooling and forward visibility.

Ed Holyoke
 
The full answer to your simple question could get quite complex. If you can only rev to 2500rpm at full throttle at say 6000' then there is something wrong somewhere. I had the same set up as you and could over-rev the prop - I was never brave/daft enough to find out by how much. I would not change the prop pitch, at least to start with. Ensure your instruments are reading correctly, the check the engine mag timing, plug gaps, air & fuel filter cleanliness and so on. Do you have good wheel pants & gear leg fairings? Many more potential problems! Go fly and enjoy the airplane, then figure out how to get more speed.
Pete
 
No manifold gauge. I am only seeing 2500 rpm max. I'm not sure if it is a reading error. I need to get an optical tach to test it.
My cruise speed is good, at 4500' doing a 2 way test I got 207mph and 178mph, but If it really isn't making 2600 I want to adjust it for better takeoff/ high density altitude performance.

If you have a mechanical tach they can easily be 25 to 50 RPM out. Sensenich wants to be sure to have your tach calibrated as the 2600RPM limit is real for safety as others have mentioned.
I used to fly with this prop, and always got around 2550 at 5000 ft Pressure Altitude. That is what Sensenich intended. Expect 2200 to 2300 on takeoff.
 
I just bought an RV-6A with an o320 160hp Lycoming and a Sensenich 70CM7S9-0 (79) PITCH PROP.
What should the max rpm be in cruise?
POH says run at 2200 to 2500 rpm and do not exceed 2600 rpm. What are most people seeing at full throttle in cruise?

Thanks
Rob,
Don't know if this helps but I thought I'd comment because I have one of these props. Also like to point out that I have a Vans tachometer and given the previously mentioned calibration range I stick to 2500RPM and below. I can exceed 2600RPM but I usually have to be a bit high to do it. The prop is pitched to 79 and my static RPM it typically 2150. Please keep in mind that I fly out of a 4500MSL airport with hot summers and DA between 8K and 9K so the numbers vary year round.
Yesterday while it was cool outside with myself and 15 gallons of fuel (1049 empty) at 7000MSL I was showing 202 MPH true at 2500 RPM and 26 inches MP. My Vernier throttle position was about an inch short of full to stay away from the 2600 RPM limit. I don't know if it matters but I have 9.4 compression pistons and an E mag. I have a buddy with the same prop but pitched slightly less and he does throttle back substantially more (At altitude) to avoid the 2600 limit.
Kirk
Kirk
 
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