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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