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From: Bulent Aliev <atlasyts@bellsouth.net>
Subject: Re: [FlyRotary] Fuel Pressure Regulator Vacuum or Boost??
Date: Thu, 21 Sep 2006 21:34:11 -0400
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Ed, my FPR is from Aeromotive and it is MP referenced. The FP is  
lowest at idle and than starts climbing with rise of MP.
Bulent "Buly" Aliev
FXE Ft lauderdale, FL
http://tinyurl.com/s5xw8

On Sep 21, 2006, at 1:57 PM, Ed Anderson wrote:

> For the entire life of my rotary powered RV-6A, I have flown with a  
> "Boost Referenced" adjustable fuel pressure regulator from MSD.  As  
> you know, it is desirable to keep the pressure differential between  
> the injector fuel rail pressure and the manifold pressure a  
> constant for best fuel injection control.
>
> I flew for several years thinking that since my pressure regulator  
> was manifold reference that it was indeed doing this.  Then the  
> light bulb came on - my fuel pressure holds rock-steady at 43 PSI -  
> and does not vary between idle and WOT!  This certainly implies  
> that the fuel pressure IS NOT varying as a function of manifold  
> pressure.
>
> Then doing some recent research on fuel pressure regulators, I  
> noticed that some say they are "Boost Referenced" and other's say  
> "Vacuum/Boost Referenced".   My conclusion (which may be  
> incorrect)  is that while my pressure regulator is "Boost  
> Referenced" it is not "Vacuum Referenced".  The difference (If I  
> understand it correctly ) is that my regulator would increase fuel  
> pressure IF it ever encounter manifold pressure greater than  
> ambient - since I am not used forced induction that never happens -  
> which in turn appears to be the reason I never see the fuel  
> pressure changing in response to manifold "vacuum".
>
> So my question to those who realllllllyyyyyy know -  is it correct  
> that for my NA 13B I need a fuel pressure regulator that responses  
> to manifold "Vacuum" or is the difference in description between  
> "vacuum referenced and boost referenced " just semantics in  
> advertising?
>
> Thanks
>
> Ed
>
> Ed Anderson
> Rv-6A N494BW Rotary Powered
> Matthews, NC
> eanderson@carolina.rr.com
> http://members.cox.net/rogersda/rotary/configs.htm#N494BW
>