----- Original Message -----

From: Ed Anderson

To: Rotary motors in aircraft

Sent: Monday, June 04, 2007 7:20 AM

Subject: [FlyRotary] Re: EC-2/EM-2 manifold pressure

If you set your field altimeter so the needles point to field elevation then the manifold pressure of your (engine not running) should ideally read the same.  But throw in transducers and calibration and instrument error and well - you know = differences!!

 

Ed

----- Original Message -----

From: Bill Schertz

To: Rotary motors in aircraft

Sent: Monday, June 04, 2007 8:02 AM

Subject: [FlyRotary] Re: EC-2/EM-2 manifold pressure

Al, thanks for the clarification on what sensor the EM2 is reading.

 

When I set an 'old fashioned' altimeter to field elevation, the engine is not running, isn't the Kolsman window reading the local pressure -- ie the 'manifold' pressure?

Bill Schertz
KIS Cruiser #4045

----- Original Message -----

From: Al Gietzen

To: Rotary motors in aircraft

Sent: Sunday, June 03, 2007 11:55 AM

Subject: [FlyRotary] Re: EC-2/EM-2 manifold pressure

 

Ed,

When I have my EM-2 on, EC-2 off, the Manifold pressure reads the barometric pressure (29.7 today).

 

When I then turn on the EC-2, the manifold pressure increases to 32.9.  This seems peculiar, have you noticed anything like this?

 

Bill Schertz
KIS Cruiser #4045

When the EC2 is off, it is using the reading from the sensor in the EM2.  When it is on, it is reading the sensor in the EC2. I have also found considerable disagreement on these sensors.  I also found that I had to change the calibration on the MAP pressure channel on the EM2 to get the correct reading (with EC2 on, we don’t care what the sensor in the EM2 is reading).  I have no idea why the calibration should be different on different units that use the same sensor; but there it is.  You can get a vacuum gage (actually a pressure gage, so you have to subtract from atmospheric) at a reasonable price from McMaster-Carr, or I could loan you mine. 

 

Also, it should not necessarily read the barometric pressure; you have to adjust for altitude.  Barometric is equivalent sea level (or something like that).

 

Al