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#1 Which fuel pump to use ?
Posted: Thu Aug 06, 2015 10:09 pm
by dal2.0litrefrogeye
Hi , thinking ahead a little here , but what fuel pump are people runnng ,with tripple webers , and around 300 hp mark ? cheers for any ideas
#2
Posted: Fri Aug 07, 2015 5:38 am
by JEP41
Hi,
I have 330 hp at the flywheel and use a facet red top. I have two red top pumps wired in but with a selector switch. One pump is sufficient, I just like the reliability factor of having a backup pump available. Its the gas turbine engineer in me 8)
#3
Posted: Fri Aug 07, 2015 6:28 am
by dal2.0litrefrogeye
Hi thanks for reply , are the pumps plumbed in, in parallel ?
#4
Posted: Fri Aug 07, 2015 9:28 am
by markc555
Webers hate high fuel pressure, it'll cause havoc with the float chambers (and leaks), so ensure you fit a fuel pressure regulator.
They only need 2.5-3psi of constant fuel pressure but the pump needs to be capable of providing sufficient fuel volume to keep the float chambers full while the engine devours the fuel exiting the carbs.
Cheers
Mark
#5
Posted: Fri Aug 07, 2015 10:20 am
by Heuer
The SU AUF 300 range of high pressure pumps are designed to provide approximately 140 pints of fuel per hour at a point about 3 foot above the level of the tank. It is thus capable of supplying fuel at this rate when ascending the most severe gradients likely to be encountered. The fuel pressure is about 3.8psi. On the other hand the SU carburetors are designed for a fuel pressure of 2psi and pressures in excess can result in leaks, increased fuel consumption and overly rich running at idle. Now I know much of the fuel going into a Weber is used to fill the cabin with fumes and give the driver a headache
but even they can't consume more than 17.5 gallons/hour or 3.5 mpg at a steady 60mph
Suggest you fit a Filter King:
viewtopic.php?t=164 CMC recommend fitting them on every car they have in for service.
#6
Posted: Fri Aug 07, 2015 6:29 pm
by David Oslo
JEP41 wrote:Hi,
I just like the reliability factor of having a backup pump available. Its the gas turbine engineer in me 8)
Do you run seperate fuel lines from the twin pumps, one down each side of the car? :D And what about the reliability of the switch ? The more parts you add the more parts you have to fail :D Interesting SIL calculations to be done!
#7
Posted: Sat Aug 08, 2015 5:42 am
by JEP41
Hi,
I have both Facets mounted in the boot and tubed into a 3/8" supply line to the webers via two non return valves in the pump discharge lines to prevent back feed. In the engine bay I use a pressure regulator set at 2.5 psig from memory.
#8
Posted: Sat Aug 08, 2015 10:18 am
by dal2.0litrefrogeye
Hi much food for thouht , as I said , a little way off yet , but if you dont ask you never know
#9
Posted: Sat Aug 08, 2015 4:33 pm
by D COUPE
JEP41 wrote:Hi,
I have both Facets mounted in the boot and tubed into a 3/8" supply line to the webers via two non return valves in the pump discharge lines to prevent back feed. In the engine bay I use a pressure regulator set at 2.5 psig from memory.
Top planning....just when I thought I had thought of every eventuality
Dave C