Fuel Pressure Drop On Acceleration
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From: East Central Florida
Fuel Pressure Drop On Acceleration I did some calculating.
0.73 g/cm3 * (2.54cm/in)**3 * lb/454g =
Dg= 0.0263 lb/in3 for gasoline.
If you multiply this by the length of the
fuel line from the outlet of the fuel
pressure regulator, forward to wherever
you are measuring, you will have a pressure
drop of
Dg * {length (in)} * {longitudinal g-force}
So if you managed to accelerate at 1g (which
is pretty sporty) and had 6' of fuel line,
you would see an injector-end pressure drop
of
0.0263 * 72 * 1.0 = 1.89 lb/in2
Almost 2PSI drop, for the cars that have the
pressure regulator back in the tank. If you
the regulator up front, and a return line,
this specific issue is nulled by the reg.
The other thing this says is, anything more
than 2PSI drop is due to something else, and
can be eliminated by upgrading fuel line,
wiring or pump.
If you're in second gear or above, and aren't
some kind of NHRA monster, you probably aren't
accelerating at 1g and the drop should be less
than that 2PSI.
Food for thought.
0.73 g/cm3 * (2.54cm/in)**3 * lb/454g =
Dg= 0.0263 lb/in3 for gasoline.
If you multiply this by the length of the
fuel line from the outlet of the fuel
pressure regulator, forward to wherever
you are measuring, you will have a pressure
drop of
Dg * {length (in)} * {longitudinal g-force}
So if you managed to accelerate at 1g (which
is pretty sporty) and had 6' of fuel line,
you would see an injector-end pressure drop
of
0.0263 * 72 * 1.0 = 1.89 lb/in2
Almost 2PSI drop, for the cars that have the
pressure regulator back in the tank. If you
the regulator up front, and a return line,
this specific issue is nulled by the reg.
The other thing this says is, anything more
than 2PSI drop is due to something else, and
can be eliminated by upgrading fuel line,
wiring or pump.
If you're in second gear or above, and aren't
some kind of NHRA monster, you probably aren't
accelerating at 1g and the drop should be less
than that 2PSI.
Food for thought.
