TSIO-360 How much manifold pressure ?

[hubcap]

For those experienced with the TSIO-360, how many inches of manifold pressure can you generate when you get up in the flight levels?

[geoffb]

Depends on the model and modifications, if any.  The -MB will make 36 inches higher than I've flown it (FL210)

[Will.iam]

Isn’t that the definition of critical altitude— the altitude at which you can still make full  MP? In that case a look at the POH for 252 shows 24,000ft and IIRC the 231 is 16,000ft unless you put on the merlin wastegate controller then is it 22,000ft? Don’t have that version. 

[carusoam]

+1 for defining critical altitude… and fancy waste gates… and how you know your waste gate may be mis-behaving…

If you are not familiar with mouse milk, and how to lubricate your waste gate… you might ask… “what MP do you guys see?” 

NA PP thoughts only, not a TC’d PP…

Best regards,

-a-

[A64Pilot]

2 hours ago, Will.iam said:

Isn’t that the definition of critical altitude— the altitude at which you can still make full  MP? In that case a look at the POH for 252 shows 24,000ft and IIRC the 231 is 16,000ft unless you put on the merlin wastegate controller then is it 22,000ft? Don’t have that version. 

I had to look it up as I thought it was max continuous power, but this is the FAA definition

Critical altitude means the maximum altitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed, a specified power or a specified  manifold pressure. Unless otherwise stated, the  critical altitude is the maximum altitude at which it is possible to maintain, at the maximum continuous rotational speed, one of the following: 

(1) The maximum continuous power, in the case of engines for which this power rating is the same at sea level and at the rated altitude. 

(2) The maximum continuous rated manifold pressure, in the case of engines, the maximum continuous power of which is governed by a constant  manifold pressure.

Edited April 28, 2022 by A64Pilot

[Will.iam]

22 minutes ago, A64Pilot said:

I had to look it up as I thought it was max continuous power, but this is the FAA definition

Critical altitude means the maximum altitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed, a specified power or a specified  manifold pressure. Unless otherwise stated, the  critical altitude is the maximum altitude at which it is possible to maintain, at the maximum continuous rotational speed, one of the following: 

(1) The maximum continuous power, in the case of engines for which this power rating is the same at sea level and at the rated altitude. 

(2) The maximum continuous rated manifold pressure, in the case of engines, the maximum continuous power of which is governed by a constant  manifold pressure.

Well apparently mooney didn’t read the Faa’s definition either as here is a quote straight out of my POH:

Critical Altitude Flight CheckAt an altitude above 10,000 ft. pressure altitude (altimeter set to 29.92" Hg) establish a 96 KIAS climb and full throttle operation not to exceed 36.0" Hg MP and 2700 RPM. Record the altitude, outside air temperature, and fuel ·flow at the point the MP can no Longer maintain 36.0". Refer to SERVICE AND MAINTENANCE MANUAL for specific actions.

[A64Pilot]

I don’t see where they didn’t? They specify 36 as the target MP, so you establish 36 and hold it until it can’t maintain it, record the test numbers. The altitude where you couldn’t quite get 36 is the critical altitude. Apparently 36 is max continuous power, but many engines are allowed to operate at a higher power but are time limited, for instance an IO-520 in a 210 can be operated at 300 HP but only for 5 min, 285 is max continuous, RPM as opposed to manifold pressure limits

That is exactly how we “topped” helicopter engines, climbed at 100% torque until rotor drooped in RPM, record numbers and chart them out, determine engines specification torque ratio.

Edited April 29, 2022 by A64Pilot