how big a fuel pump"



how big a fuel pump"

Postby grumpyvette » June 2nd, 2011, 7:51 pm

HEY GRUMPYVETTE??

I've been reading a little about gph vs horsepower and not sure I understand it exactly. The Free-flow number is always what they advertise and the actual needed is much less. I'm trying to support a 600hp engine, but don't know if 110 gph will suffice or if I'll need to step up to 130 gph.



fuel pumps are usually rated at no resistance flow and they flow significantly less pushing fuel to a fuel pressure regulator and carb of any style
The average advertised weight of a gallon of premium fuel is 6.34 lb/gallon.
Brake Specific Fuel Consumption or B.S.F.C.
Brake Specific Fuel Consumption or B.S.F.C. is the amount of fuel required to produce 1 HP for 1 hour. This means that an engine with a B.S.F.C of .5 will burn 1/2 or .5 lbs of fuel to produce 1 HP for one hour. Determining exact B.S.F.C for a specific engine is complicated and requires an engine dyno.
Based on industry standards the B.S.F.C for:
Normal Aspirated Engines is .45 - .55
Supercharged Engines is .55 - .60
Turbocharged Engines is .6 - .65


need to calculate fuel required:
Target Hp * B.S.F.C. = Fuel required in lbs/hr
600 *.56 = 330 lbs/hr
Most fuel pumps flow rate is advertised in gallons per hour:
Lbs/hr / fuel weight per gallon = gal/hr
330 / 6.34 = 52 gal/hr
but remember pump losses, and a fuel pressure regulator and a return line fuel feed system designs flow requirements ?
ID select the 130gph pump an AN8 fuel lines

http://www.centuryperformance.com/fuel.asp

READ THRU THIS AND SUB LINKS
viewtopic.php?f=55&t=1939

viewtopic.php?f=55&t=211

viewtopic.php?f=55&t=635

Image
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: how big a fuel pump"

Postby grumpyvette » July 3rd, 2011, 9:46 am

btw occasionally you'll find applications where the new electric fuel pump or even a manual fuel pump works great in cool weather but under hot temps the fuel pressure at the carburetor slowly increases, even when the fuel pressure regulator works perfectly when tested, its frequently the result of a pressurized non-vented fuel tank and not maintaining the empty tanks open air space at outside atmospheric pressure, many fuel tanks have a one way vent they are designed to let air in as fuels used but not to let vapors out.

the quick fix is a larger vent in the fuel tank, but usually you'll want it to be vented with a long 1/4" inside diam vent line tube,that routes vapors out to a line that ends in the air filter housing for the carburetor, not just a hole drilled in the tank cap, your problems common and it has little or nothing to do with the pump style, used.

think about it a bit, your fuel pump can only pump whats in the tank in a circle from pump to carburetor and back to the tank thru the return line, theres no way the fuel circulating adds volume, but if the tanks not vented as the fuel heats it expands, and increased pressure in the tanks return line effects the carburetor and return regulator pressure, the return line needs to be at zero for the regulator to function correctly and accurately.

btw if you mount an electric fuel pump in the fuel cell or fuel tank its cooled by sloshing fuel, if the tank gets lower than about 1/4 full this tends to reduce the cooling capacity and reduce the fuel pumps expected life expectancy , so try to keep the tank above the 1/4 full level to maintain fuel pump durability if its mounted IN THE TANK



" If your having that as an issue, the quick fix is a larger vent in the fuel tank, but usually you'll want it to be vented with a long 1/4" inside diam vent line tube,that routes vapors out to a line that ends in the air filter housing for the carburetor"
personally ID add a small disposable fuel filter on the vacuum line to act as a safety flash suppressor in case of a back fire

a bit of creative fabrication a hole dilled, a fitting and maybe some J&B epoxy and you can do this
Image



Image

Image
plastic fiittings break under stress or with age and should be avoided
viewtopic.php?f=52&t=2005&p=5328#p5328

viewtopic.php?f=55&t=211


Image
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida


Return to Engine: Repairs , Modifications ,trouble shooting and tunning

Who is online

Users browsing this forum: No registered users and 4 guests

cron