Fuel system limits...
Thread Starter
|
Senior Member
Joined: Mar 2000
Posts: 4,297
Likes: 0
From: Clifton, NJ, USA
Fuel system limits...
Since telling a friend of mine about the KB blower pushing 500+hp without an upgrade to the fuel system and him not believing me, we ran out and found some calculations.
HP = ((IFR * # of injectors * .8) / BSFC)
IFR = Injector Flow Rate (lbs/hr)
BSFC = Brake Specific Fuel Consumption
(determined from engine dyno measurements
.4-.6 is the range for gasoline engines,
Formula 1 Extrude Honed motors make BSFC of .44,
so we use .5)
BSFC = pounds of fuel per hour/brake horsepower
.8 = 80% injector duty cycle.
537.6 = ((42 * 8 * .8) / .5)
So looks like out theorectical max at ~540hp. Sound right? I don't know when the 42# Ford injectors nessecarily go static with the stock fuel pumps, but bumping up the fuel pressure with something like Sal's bigger pumps would push this number up some too.
Daniel
PS - Cool little resource for math forumla for cars:
http://www.pro-flow.com/mustmath.htm
http://www.smokemup.com/utilities/ca...l_injector.cfm
http://www.dsm-performance.com/catal..._injectors.php
HP = ((IFR * # of injectors * .8) / BSFC)
IFR = Injector Flow Rate (lbs/hr)
BSFC = Brake Specific Fuel Consumption
(determined from engine dyno measurements
.4-.6 is the range for gasoline engines,
Formula 1 Extrude Honed motors make BSFC of .44,
so we use .5)
BSFC = pounds of fuel per hour/brake horsepower
.8 = 80% injector duty cycle.
537.6 = ((42 * 8 * .8) / .5)
So looks like out theorectical max at ~540hp. Sound right? I don't know when the 42# Ford injectors nessecarily go static with the stock fuel pumps, but bumping up the fuel pressure with something like Sal's bigger pumps would push this number up some too.
Daniel
PS - Cool little resource for math forumla for cars:
http://www.pro-flow.com/mustmath.htm
http://www.smokemup.com/utilities/ca...l_injector.cfm
http://www.dsm-performance.com/catal..._injectors.php
Senior Member
Joined: Oct 2001
Posts: 4,815
Likes: 0
From: Richmond,VA
That figure is for HP @ the Flywheel though right? I dont know what JL has dont to his fuel system but he is over that at the rear wheels...
And Sal is WAY over that at the rear wheels so his fuel upgrade must work!!!
And Sal is WAY over that at the rear wheels so his fuel upgrade must work!!!
Senior Member
Joined: Nov 2000
Posts: 6,713
Likes: 0
From: Orland Park, IL just south of chicago
yeah but you have to remember sal is running a wet kit that can push extra fuel through the nozzle and make up for the injectors if he wants too. not that much, but enough.
The new fuel pumps are sweet and if anything a little bit of insurance to keep me happy.
I do think by the end of this year the tuners are going to be running 50lb+ injectors on there trucks.
The new fuel pumps are sweet and if anything a little bit of insurance to keep me happy.
I do think by the end of this year the tuners are going to be running 50lb+ injectors on there trucks.
Member
Joined: Jan 2002
Posts: 90
Likes: 0
From: Fairfax, VA
FYI, most supercharged apps figure .55 BSFC, you need more fuel to deal with the boost. Following your equation, you get somewhere in the neighborhood of 488 horsepower.
Now the thing is, I usually figure 90% duty cycle instead of 80%, so if you take that into account:
549 BHP. Note that every engine's different, etc., but that gives you some idea. This kind of figuring was spot on for my Mustang, BTW. Now does anyone know the max theoretical for the fuel pump(s) in the tank? I don't even know what kind of fuel pump we have in a Lightning...
Now the thing is, I usually figure 90% duty cycle instead of 80%, so if you take that into account:
549 BHP. Note that every engine's different, etc., but that gives you some idea. This kind of figuring was spot on for my Mustang, BTW. Now does anyone know the max theoretical for the fuel pump(s) in the tank? I don't even know what kind of fuel pump we have in a Lightning...
