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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
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