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Dave,
I get 29-30.5 inches consistently. My elevation is 55 feet. MP is a factor
of baro plus I get a ram of about an inch.
Bill B
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Dave
Sent: Tuesday, August 21, 2012 2:51 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Turbo question.
If you havent changed prop settings for any of those readings, then the turbo and plumbing appears to be a restriction, not a boost. I'd consider further instrumentation to find the source of the restriction, such as a boost gauge just beyond the turbo to read MP before it goes through the intercooler. Another boost gauge should go between the intercooler and the throttle body. The "regular" MP gauge should be tapped onto the manifold after the throttle body, and the readings reflect that it probably is. Your intercooler may be the source of the restriction, or the turbo itself may be the problem.
But clearly your engine is breathing and making better power without the turbo in line.
I will also say I've NEVER EVER seen a normally aspirated engine getting 29 inches MP while running.. usually 27 is the best I've seen. I'd consider checking calibration somehow.
Dave
On 8/20/2012 8:17 PM, Chris Barber wrote:
As I have mentioned I have had what I think are incongruent readings
regarding my manifold pressure (mp)and engine rpm. It seems I am getting
quite low mp as I add power to higher rpm.
I am not well versed in this area but my thought is that as I add power,
even with slight boost (currently using a 3 lb spring in my wastegate)
eventually my mp should raise a bit more.
Today I did some static test. I recorded engine RPM with the turbo hooked
up and recorded the mp at 1000 rpm increments. Then I removed the turbo
plumbing from my intake and recorded the same info My results currently
confuse me.
With the turbo hooked up I am getting
RPM. MP inches
2000 - 14.0
3000 - 15.5
4000 - 19.3
5000 - 21.6
5700 - 24.5 (topped out)
With the turbo removed.
2000 - 15.8
3000 - 15.3
4000 - 19.7
5000 - 24.8
5833 - 29.8
Is this indicative of restriction in my plumbing? Perhaps in the inter
cooler? A dirty air filter? A bad pop off valve or a leak not allowing the
air pressure getting to the intake. Or????
I am uncertain what other permitters I need to check and provide. I am
just starting my diagnosis in my Phase One testing. I only have 1.6 hours in
the air so far. I value ya'll's direction and input.
Heck, perhaps this is working properly but it just doesn't seem
right/comfortable.
Thanks folks.
Chris Barber
Houston
Velocity SE
Rotary 13b turbo (?) :-)
Sent from my iPhone 4
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