OAT and turbo

[Ulysse]

Can OAT affect maximum MAP during takeoff on a turbo engine?

[Shadrach]

5 hours ago, Ulysse said:

Can OAT affect maximum MAP during takeoff on a turbo engine?

Yes. DA input will affect MP output. Critical altitude is always given on a standard day for this reason. That being said, while theoretically you should still be able to make maximum power at any DA below critical altitude, the turbo will need to work harder as the DA increases.

 

[Will.iam]

13 hours ago, Ulysse said:

Can OAT affect maximum MAP during takeoff on a turbo engine?

What airplane are you referencing? A 231 you will need to use more throttle on a hot day than a cold day. A 252 or later mooney with a wastegate controller will compensate for the hotter or colder temps. I. E. I see 36” MP whether freezing or 100 degrees at sea level or at any airport above sea level. If I don’t see 36” MP pressure on T/O i abort the takeoff to find out why. 

[Ulysse]

In my aircraft, MP is 39" at takeoff. During 2 hot days (around 42 degC), MP was limited to 38". It went back to 39" on cooler days. 

[Will.iam]

interesting that you have a variable controlled turbo and it could not maintain 39" on very hot day.  I have to admit I have not flown at 42 deg C yet as the hottest I have flown so far has been 39 deg C but I had 36" at takeoff that day.

 

[Pinecone]

Critical altitude should be a density altitude thing.  But the critical altitude of an Encore should be 21,000  The 252 is 24,000.

If you cannot get full manifold pressure on takeoff, unless departing from the top of Mount Everest, something is wrong.   Probably an induction leak.

[kortopates]

You didn’t say what engine model you have. A hydraulically controlled wastegate such as in a 252 and Encore will see variation in max Map based on oil temp - not air temp. It will under boost with hot oil (above normal) and over boost with cold oil. You’re probably seeing normal effect from hot oil.


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[LANCECASPER]

1 hour ago, kortopates said:

You didn’t say what engine model you have. A hydraulically controlled wastegate such as in a 252 and Encore will see variation in max Map based on oil temp - not oil temp. It will under boost with hot oil (above normal) and over boost with cold oil. You’re probably seeing normal effect from hot oil.


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He has an Encore which is a TSIO-360-SB

[kortopates]

He has an Encore which is a TSIO-360-SB

Yep, perfectly normal.


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