Max RPM for constant speed

My IO360 with CS prop is rated full power at 2700 rpm.

Actual RPM on takeoff is usually around 2615. Should I have the
governor adjusted, or is this appropriate margin to prevent overspeed?

First, I'd get an optical tach and see how fast it's actually turning
compared to what the mechanical tach indicates.

Jim

"Paul kgyy" wrote in message
oups.com...
My IO360 with CS prop is rated full power at 2700 rpm.

Actual RPM on takeoff is usually around 2615. Should I have the
governor adjusted, or is this appropriate margin to prevent overspeed?

Jim's advice is wise and just to compare, my plane always shows 2710 to 2730
on take-off and it is an IO360 200 HP.

Kobra


"Paul kgyy" wrote in message
oups.com...
My IO360 with CS prop is rated full power at 2700 rpm.

Actual RPM on takeoff is usually around 2615. Should I have the
governor adjusted, or is this appropriate margin to prevent overspeed?

Sorry, I should have mentioned that I have a digital tach.

Yes, have the gov adjusted. You should be able to get 2700+-25Rpm. The
extra 85 RPM translates to much higher takeoff engine power.

You can check the accuracy of your tach at 1800 rpm by doing a runup at
night with a street light in back of you. Due to the strobe effect, the
prop should appear to stop at 1800 rpm (for a two blade prop). For a 3
blade prop, it should appear to stop at 1200 and 2400 rpm. Good
inexpensive accurate double check on tach accuracy.

Paul kgyy wrote:
My IO360 with CS prop is rated full power at 2700 rpm.

Actual RPM on takeoff is usually around 2615. Should I have the
governor adjusted, or is this appropriate margin to prevent overspeed?

Its not unusual for tachs to read wrong, but assuming its a correct
reading, I would have it adjusted. In the Mooney community we often try
to get the A&Ps to adjust it to 2800 RPM max. For a normal take off we
pull the blue lever back just a bit to keep it at 2700. But for a short
field take off (especially for Mexico operations) we'll push 2800 for
short periods of time. Also, the Mooney factory tells us that climbing
out at 2600 is very hard on the engine. Much of the cooling an IO-360
receives is from fuel and having the prop turn at 2600 reduces fuel
burn, which increases climb out temps interally. My IO-360 pulls 19
gal/hr in climb out and about 10 gal/hr in cruise.
The IO-360 engine is a bit unusual because Lycoming actually certified
it to run 2000 hours at sea level at 2700 RPM. There is no reason to
pull power back.

-Robert, M20F

Paul kgyy wrote:
My IO360 with CS prop is rated full power at 2700 rpm.

Actual RPM on takeoff is usually around 2615. Should I have the
governor adjusted, or is this appropriate margin to prevent overspeed?

Max rpm on my IO-520 is 2700. Actual rpm during takeoff, which I know
because I have a Horizon digital tach, 2725-2750. I would never let the
rpm stay on the low side, you're just ****ing away HP. When I had my
182 the governor was set at about 2650 when the redline was 2600. 50
rpm here or there are irrelavant.

"Robert M. Gary" wrote:
Also, the Mooney factory tells us that climbing
out at 2600 is very hard on the engine. Much of the cooling an IO-360
receives is from fuel and having the prop turn at 2600 reduces fuel
burn, which increases climb out temps interally.

Somebody at the Mooney factory is smoking some powerful stuff.

--
Dan
C-172RG at BFM

Somebody at the Mooney factory is smoking some powerful stuff.

Not at all. There is a mountain of engineering data concluding that
reducing RPM reduces fuel flow and cooling. In fact, I just spoke with
one of the test pilot the other day who talked about flying the
instrumention for that. Its too bad Cessna doesn't do the same level of
engineering.

-Robert