Hello all,
I'm currently building a B18a for boost and I'm contemplating on my fuel setup. I'm starting to get close to finished for the build and I need to figure out what HP numbers I can see with the stock fuel filter, fuel rail, and Fuel regulator I can handle.

I'm only looking to see 350-400HP. If the OEM fuel system (minus the pump) is adequate enough to support the HP then why change it?

 

Stock fuel system with 255 LPH pump is typically good for up to about 600 HP. Plus it all depends on what size injectors you run and other factors....

Since mostly there is not any good info on here just use these formula's I took the time to post below...

INJECTOR SIZE CALCULATION

Injector Size in lbs/hr per Injector = Expected HP X BSFC / Number of Injectors

For BSFC RICH = .60 Race Gas/Mid Range = .50 LEAN = .45

Injector sice in cc/min = [(Injector size in lbs/hr X 454) / 60] / .75


FUEL PUMP SIZE CALCULATION

Total Fuel Flow = Injector Fuel Flow in lb/hr X Number of Injectors

Fuel Flow in Gallons Per Hour = Total Fuel Flow in lb/hr / 6.25

To convert to Liters Per Hour = Fuel Flow in Gallons Per Hour X 3.8 = Fuel Flow in Liters Per Hour


If you can't understand that then you are beyond help, and go back to school for Math, Please...

 

well the injector calculation I knew about, however; I didnt know about the fuel pump calculation so I now know for 400hp I need at least 850cc injectors with a 195lph fuel pump. So I'm sure 1000cc with a 255lph walbro would cover that.

But what I was more so worried about whas the stock diameter of the fuel line and rail, the capabilities of the oem fuel regulator, and the ability to of hte oem to filter that much fuel...

 

all the oem lines/rails/filter will be fine up to the limits of the walbro pump (600ish)

 

I'm thinking I read somewhere that the fuel pressure will rise with the new walbro. I think someone said they opened the orfice to allow pressure to lower...

can anyone confirm this? I have researched it several times and I can seem to find it. I will upgrade every component with time but at the moment I'm tryign to hold 2k back for my turbo/ecu/tune...

 

no need to mess with the fpr, it might raise the pressure up, but thats why i always install them at the tuners so that way the car gets tuned and all is good

 

yeah I suppose it can be tuned to accomidate for the higher psi. I will have a Fuel Pressure Guage so the tuner will know.

 

Thank-you for the equation I also need the fuel pump one

 

You are welcome... This should be put in the FAQ's because it is useful to people that don't know these formulas and is not the typical b/s answers you see on here...