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Date: Tue, 21 Aug 2012 13:50:30 -0500
From: Dave <david.staten@gmail.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Turbo question.
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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
> --
> Homepage:  http://www.flyrotary.com/
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>