Injectors and Boxes vs. Fuel Pressure

[Diesel Freak]

I have been doing some thinking..... Follow my logic if you can.



Installing larger fuel injectors will not lower fuel pressure at the VP44 inlet.



Why?



The VP44 is a positive displacement pump, and pumps a specific ammount of fuel to each injector regardless of the flow rate of the injector.



Larger injectors have a lower pop off pressure and larger holes in the nozzle, therefore they flow more, and less fuel is diverted back through the injector galley to the fuel tank.



VP44 flow rate is the same regardless of injector size. The only difference is unused fuel. Smaller injectors divert more fuel back to the tank than larger injectors.



Here is the kicker... once the flow rate of the VP44 is changed (with a fueling box) then fuel pressure will drop.



The bottom line



Injectors will not change VP44 fuel flow rate and will not lower fuel pressure from stock pressure levels



Fueling boxes will change VP44 fuel flow rate and will lower fuel pressure from stock pressure levels.

 

[Todd T]

its called

Duty Cycle

 

[Diesel Freak]

Duty Cycle of the Solenoid?

 

[HeberRam]

Fuel pressure

SPOCK. . I find your logic perhaps valid. . However, in my expierence the opposite is truly what happens. Increasing injector sizes, fueling boxes, yes and even larger turbo's have reduced fuel pressure to my VP44 pump. So much so I have installed a pusher-pump. The problem is not the VP44 pump, it is the ability of the lift pump to keep up with the demand.

 

[Diesel Freak]

hehe