Manifold Pressure at 10k

[Grum.Man]

Just curious what others are seeing out of their naturally aspirated singles at 10k. I'm getting about 21" MAP at 10k MSL WOT.

 

[Fearless Tower]

Just curious what others are seeing out of their naturally aspirated singles at 10k. I'm getting about 21" MAP at 10k MSL WOT.

21" sounds pretty good. I get around 20" in the IO-470s of my Baron at 10k which is what the book says I should see.

 

[Pilawt]

Yep, 20" at 9,500', WOT, O-360-A4M (fixed pitch).

 

[James331]

Think you loose a inch per 1k

 

[Grum.Man]

That's what I've heard too. I always read the venture intake design gets slight pressurization so was just curious if it was true. Pretty minuscule regardless.

 

[SkyDog58]

The PHAK states:

A standard pressure lapse rate is one in which pressure decreases at a rate of approximately 1 "Hg per 1,000 feet of altitude gain to 10,000 feet. [Figure 3-2] The International Civil Aviation Organization (ICAO) has established this as a worldwide standard, and it is often referred to as International Standard Atmosphere (ISA) or ICAO Standard Atmosphere. Any temperature or pressure that differs from the standard lapse rates is considered nonstandard temperature and pressure.

And it has this nice chart.

 

[Hank S]

I'm just over 20" usually. But I also reduce throttle to shut off the WOT enrichment circuit; I therefore fly at 20" rather that WOT. It can be a third of throttle travel before the MP needle moves, indicating that the circuit is disengaged. The turbulence from the cocked throttle plate helps with atomization of the fuel, evening distribution and enabling me to run slightly LOP (not common for carbed engines).

 

[Clark1961]

I get 30" (or more) at 10k....not naturally aspirated though...

 

[coloradobluesky]

It does depend on temperature and pressure. So it will differ a bit from day to day. Turbo is a different story altogether.

 

[denverpilot]

1" / 1000' is close enough for government work. Yours doesn't sound out of whack at all.

In the turbos if they're fixed waste gate types, you climb a thousand, add back the inch you lost, climb another thousand, add another inch...

My Dodge Cummins turbodiesel will also do 32" but I limit it to 30" in the computer with an alarm to get my foot out of it. Also have to limit EGT to 1300 or so. Heh.