Crossflow EFI stock fuel pump performance.

[Crazy2287 1,886]

Details of the stock fuel pump.

I have had it providing 220RWHP with the stock injectors at 100% duty cycle.
I just carried out a crude flow test and it flowed 2L at 43.5psi (stock pressure) in 1min 14sec at 11.5v. = 160lb/H (19.2Gp/H) or 100Lp/H This works out to maximum injector size of 21lb/h if driving to 80% duty. So.. now you know.

 

I'm running 42lb/h injectors that peak at 60% duty which equals about 25lb/h, Using a digital pressure gauge i have not seen a drop in rail pressure but this test reveals i am on the very edge of the peak for the stock pump. The extra few lb/H is likely due to the 12.4-13.4V operating voltage vs the 11.5v test voltage. (more volts = more pump)

 

I might carry out a second test at 13.0ish volts and update this thread with the result.

 

but at any rate if you start hitting 200rwhp you should think about a new pump and once you hit 220 it's definitely time for a fuel system upgrade before you go further.

[n00bus m@x1mus 465]

Good work bud... You reckon you could do similar tests with other factory pumps, like the E series and AU?? cos swapping the pumps out is fairly straight forward, and if you can score one cheap then its worth the upgrade by the sounds of it.

[Crazy2287 1,886]

Sure. All you gotta do is bypass the return line into a measured container and time how long it takes to fill and the voltage at the pump. Thats how much fuel you have available. Use any more than what is bypassed and the regulator will shut and stop regulating then your pressure will drop.

Piss easy to do if i had the units. Nil stock of either pump though...

[Crazy2287 1,886]

Ran another test. This time the batteries been on the charger all night, Pulled the boot apart to get acess to the pump and measured on the pump terminals. Averaged 12v during. i think my wiring must be a bit sub par to the pump, my own fault from when i wired it up 8 years ago. But anyway, with the better supply i got 2 liters in 1min6seconds so that 1818.2 ccm. 440cc injectors @ 80% will consume 2112cc.

Currently im demanding 1584cc at WOT peak.

Plugged it into a spreadsheet calculator i made up and i get:

With a 50% mix of ethanol in unleaded 98ron=

103.3 ron

11.85:1 stoich

1965cc fuel required.

74.4% injector duty cycle.

 

Just thought i'd put that there for interested people. Anyone wants the calculator if you plan on running ethanol pm me and i'll email it.

 

Probably going one of these pumps:

http://www.diyautotune.com/catalog/walbro-gsl392-255lph-fuel-pump-p-312.html

 

which should offer a capacity of 3467cc @ 40-45psi and 12v

 

Which will have enough headroom for 100% ethanol. 100% ethanol looks like this:

108.6ron

9:1 stoich

2587cc req fuel

98% injector duty cycle

[n00bus m@x1mus 465]

Are you doing these tests after the reg Q?? so the pump has 43lbs against it while measuring the flow rate?

[Crazy2287 1,886]

Yep.

[n00bus m@x1mus 465]

Goodo..... carry on.