fuel pressure

What HP are you expecting out of your motor?
Electric pump will give you you more flow than mechanical but only if the fuel line size allows it. I beleive the stock size fuel line will feed up to 450 bhp.
Will

425 hp

great.....thanks
rodman

Yes 7 psi for a carb, but it's not so much presuure as the regulator will maintain that once set, it's lbs/hr the fuel pump is rated for.

Based on rule of thumb where Brake Specific Fuel Consumption (BSFC) is about 0.4 for a naturally aspirated engine, your 425HP will require about 170 lbs/hr fuel. A pump manufacturer should provide a pump curve, so just select a pump that can deliver min 170 lbs/hr @ 7 psi. Oversizing to some degree is not an issue as the excess will return to the fuel tank via the regulator return.

Electric pumps are a) not good suction pumps and b) don't tolerate running dry, so should be fed from the bottom of the tank (or in tank) to remain permanently 'primed'.

Julian

...BS!!! 7 psi will blow Holley Needles Off their seats! 6 psi is 'WEP' Maximum! I run 5.0 PSI and That feeds Dual Quads(450 CFM), and I don't have any Problems. Not all Regulators have a 'return to tank', but My Mallory Regulator, Does! I have said this Before! Concerning Carbs; You Don't Need High PRESSURE!! You Need High FLOW!! (Accepting 'Fuel Injection', Ofcorse!)...

quote:

7 psi will blow Holley Needles Off their seats!

The following is from the Holley website:

appreciate all the help gentlemen. like i said i'm not familiar w/ an electric fuel pump. not only was i told to get the pump but the regulator and relay also. is all this stuff overkill for just 425+ hp? guess i should have went w/ a mehanical pump but was trying to look at accessiblety issues in the future. wasn't quite sure what changes the windsor would have. please keep the comments coming. might just do away with the electric fuel pump idea. by the way, don't know if this makes much of a difference or not but i'm running a demon 750 king carb. don't hold that against me now..........please feel free to call (337)-515-0208
thanks,
rodman

PUMP MOUNTING AND INSTALLATION:
The best location for mounting any electric fuel pump is the rear of the vehicle. The inlet and outlet of the pump must be
mounted below the lowest point of the tank. This is necessary to allow for an adequate fuel supply. The pump is designed to
push fuel and not designed to suck fuel out of the tank. It needs to be gravity-fed or if it’s pulling from the top of the tank, it
needs to develop a siphon feed to the pump. The pump should be mounted on the chassis, in a vertical position with the pump
motor on top. Avoid exposure of the pump and fuel lines to moving parts and to any hot areas, such as the exhaust manifold.
The pump should not be mounted in a closed area, such as the vehicle’s trunk.

From the King Demon Manual:

Fuel Pressure
Most gasoline powered race engines usually
require between 6 and 7 1/2 PSI fuel pressure.
Gasoline carburetors can be run either at idle or
wide open throttle at these pressures. Alcohol
carburetors usually run best with idle pressures
between 4 and 6 PSI, with full throttle pressures
between 9 and 11 PSI. Be sure your fuel
delivery system is properly adjusted and able to
maintain volume flow at these pressures. Improperly
adjusted or inadequate fuel delivery
will result in poor performance and possible
engine damage.

perfect, thanks a lot mark.......
rodman