Fuel Pump for 500+rwhp?

[Derek1224]

Seeing as I'm done all BPU mods for my car, next up is the fuel system before moving on to a larger turbo. I know about injector sizing but I've been hearing that the Walbro 255's start running out of steam as you get over the 500rwhp range. If thats the case, which pump would be recommended? Probably looking at around the 600 mark. I know MTR has a dual Walbro hanger for our cars now but if I can stick with a single pump I'd rather do that. Thanks for the help.

 

[NewWestSupras]

Try a search for an A1000. I've seen a few hipo members on here recommend it. Or perhaps ask Duane (UpgradedSupra)...

 

[csnow]

Buy a dual hanger.

 

[QWIKSTRIKE]

A1000 or the Bosch is known to be more reliable than the A1000. 2 walbros can be used, and you can use the stock hanger. I wrote a little about it recently. Try to locate it in search!

 

[hottscennessey]

Where did you guys doing dual walbro pick up the anti-magnetic foam?

 

[QWIKSTRIKE]

I will find that info and post on it. I found a place and I cant remember where I found it, because blackdevilsupra had an extra one laying around I bought it! I will call him to see if he has the source listed somewhere.

 

[hottscennessey]

Awesome, I'd really appreciate that.

 

[QWIKSTRIKE]

past post
http://www.supramania.com/forums/showthread.php?t=44137

 

[Supracentral]

I know about injector sizing but I've been hearing that the Walbro 255's start running out of steam as you get over the 500rwhp range. If thats the case, which pump would be recommended?

This is all easy to figure out if you are willing to do a little basic math.

First, we start with a Brake Specific Fuel Consumption (B.S.F.C.) rating of .60 lbs/hr for a turbocharged car. This is a measure of an engine's volumetric efficiency. We'd use a lower number (.50) for an N/A car. They just aren't as efficient.

You say you are looking for 600 at the wheels.

So we take your target HP (600) and multiply by a B.S.F.C of .60 lbs per hour for a boosted car = 360

Take 6 injectors running a max duty cycle of 80% = 4.8

Divide 360 by 4.8 = 75 lb/hr injectors

CC/MIN = LBS/HR X 9.71

So 75 x 9.71 = 728.25 cc/min

And that works out just about right. 720 cc/min injectors is enough fuel to put down 600 at the wheels anyday.

Multiply injector flow rate by 6 = 450 lbs/hr fuel total needed to get there. Use the same calc above to get to cc/min (450 X 9.71) and you get 4369.5 cc/min of fuel.

To convert cc/min to lt/hour take 4369.7 and multiply by .06 = 262 lt/hr

That's just a hair more than you can get out of your 255 lt/hr pump.

So use two. And just for shits and giggles, let's see how much power that will support.

Convert lt/hr to cc/min by multiplying by 16.6666667

So two walbros at 255 lt/hr = 510 lt/hr

510 lt/hr = 8500 cc/min

Divide that by 6 and we'll see it will support 1416.5 cc/min injectors

Divide by 10.5 to get lbs/hr, so 134.9 lbs/hr

From here it's easy to calculate what these theoretical injectors would support.

Horsepower = Inj Size (lbs/hr) x (duty cycle) / B.S.F.C.

So 134.9 x .80 / .60 = 179.86 BHP per injector

179.86 x 6 injectors = 1079 horse

So your single walbro is just a hair off from being enough. You might get away with it, might not. I wouldn't push it. And your dual walbros (theoretically) can produce enough fuel for 1079 horsepower.

Just plug in the flow rates for any other pump you are looking and you'll see if it will work.

 

[QWIKSTRIKE]

This is all easy to figure out if you are willing to do a little basic math.

Now this tidbit of infomation personally should be placed as a saved FAQ Supra Central if it isnt there since you took the time to make this formula just copy and past it forreference sakes.

thanks
Anthony

 

[Derek1224]

Supracentral,

Thanks for that awesome post! Thats exactly the sort of thing I was hoping to get as a response. That post should be a sticky somewhere if it isn't already!

Derek