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I understand that, but what I was
asking:
My field elevation is 700 feet. I set the altimeter
needle to 700 feet, the Kohlsman window reads (whatever it is that day), and
that is the manifold pressure that the EC-2 should be reading - isn't
it?
Bill Schertz
KIS Cruiser #4045
----- Original Message -----
Sent: Monday, June 04, 2007 10:22
AM
Subject: [FlyRotary] Re: EC-2/EM-2
manifold pressure
Well Bill,
if the Kolsman window is where you set your altimeter setting (mb or
inches mercury) you will never see field elevation (pressure) unless you are
at sealevel.
E.g. if you have 29.92" at sealevel (and in the window) you still have
29.92 in the window (you set it there!) when you get to 6500'. Your
actual ambient pressure is around 23.42".... (which you should be reading on
your manifold pressure gauge - engine stopped...
Unless, I got it wrong the last 15 years and 9500 hours - ohhh
my...!!
TJ
On 6/4/07, Bill
Schertz <wschertz@comcast.net> wrote:
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 -----
Sent: Sunday, June 03, 2007 11:55
AM
Subject: [FlyRotary] Re: EC-2/EM-2
manifold pressure
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 sam e 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
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