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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1413791@logan.com>
Subject: Re: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost??
Date: Thu, 21 Sep 2006 16:23:06 -0400
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Thanks, Paul

Sounds like you have a pressure regulator that is referenced to the manifold 
for both "vacuum" and boost.

Ed
----- Original Message ----- 
From: <fpbjr2001@yahoo.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, September 21, 2006 3:01 PM
Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost??


> ed
>   this is what i understand. first you set your
> regulator at static pressure no lines to it. lets say
> 38 lbs. connect the manifold hose to it. the pressure
> should be lower than 38 because of the vacumm. if you
> go positive pressure or boost it should go 1 lb per 1"
> of positive pressure above the 38lbs fuel pressure.
>   this is what the pressure on our 20b does. at idole
> it is about 32lbs and at 8lbs boost it 46lbs fuel
> pressure. we are using an aeromotive regulator.
>   i don't know about the referance you are talking
> about.
>   hope this helps.
>
>             paul brannon  N117ES
>
>
> --- Ed Anderson <eanderson@carolina.rr.com> 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
>
>
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