Pressure Difference when changing Fuel Pumps

[DUF42LParticipant NewcastleVS Exec - 4.2L Vortech 21psi 6spd View build HERE Member since: March 16, 2015 Posts: 9]

Hi Guys,

I’m wanting to change my fuel pump setup. Currently i am running a standard in-tank pump which feeds a Bosch 044 then off to a Regulator.

I would like to swap out the in-tank pump with a new 460 LPH walbro, and possibly take off the bosch.

What i am worried about is the operating pressures as the bosch flows at 72psi and walbro flows at 44psi.

would i have to muck around with my regulator or could it be just a flat out swap. is there a certain operating pressure for the injectors (or is that different for every set up)

[ImmortalityParticipant 97 HSV Senator 185i 02 VX L67 Calais View build HERE Member since: August 31, 2015 Posts: 535]

The regulator sets the system pressure (unless something down stream of the regulator is restricting flow).

Maybe what you are looking at is the rated flow at X pressure?

Fuel injectors do have an ideal operating pressure and this would normally be the pressure at which it is rated, this is why it is important to have a 1:1  ratio manifold referenced FPR (so that the injector is working at the same constant pressure regardless of how much boost is put into the engine).

Increasing the fuel pressure is one way of compensating for injectors that are to small and don’t flow enough, this works but only to a point as flow does not increase proportionately to pressure and if the pressures across the injector is to great then instead of getting a nice atomised stream of fuel it will just start to hose.  The newer style of injectors suffer much less and can handle much greater pressures but the original style EV1 injectors used in the VS era engines certainly don’t like to much pressure.

[DUF42LParticipant NewcastleVS Exec - 4.2L Vortech 21psi 6spd View build HERE Member since: March 16, 2015 Posts: 9]

Immortality wrote:

The regulator sets the system pressure (unless something down stream of the regulator is restricting flow).

OK looks like i would be ok to swap out the pump as there is no other restrictions downstream. I also just found out that the walbro 460 pump flows 390lpm at 73psi which is pretty much the same operating pressure as the bosch 044 but with 90 more LPM i should be fine.

FYI my engine is running seimens 60lb injectors and i might be upgrading them soon as well.

Can’t wait to say goodbye to my noisy 044!!!

[ImmortalityParticipant 97 HSV Senator 185i 02 VX L67 Calais View build HERE Member since: August 31, 2015 Posts: 535]

Do you know what the max duty cycle your injectors are running at?

Those Deka 60lbs injectors are rated at 3 bar/43.5 psi.

[DUF42LParticipant NewcastleVS Exec - 4.2L Vortech 21psi 6spd View build HERE Member since: March 16, 2015 Posts: 9]

they are running at 100% or close to it

 

[cava454Moderator 93 VR BT1 View build HERE Member since: February 20, 2015 Posts: 2 390]

I’d be changing inj before pump.

• This reply was modified 8 years, 7 months ago by  cava454.

[DUF42LParticipant NewcastleVS Exec - 4.2L Vortech 21psi 6spd View build HERE Member since: March 16, 2015 Posts: 9]

i was only going to change pump because my intank pump has shit itself. i am eyeing off a new set of injectors though.

[MarzellaParticipant MarzellaVS SS View build HERE Member since: March 2, 2015 Posts: 59]

Yes walbro will be fine, might want to run new bigger wiring to it.. Forget listed operating pressures, compare at your specific op pressures.

FYI 044s are not noisy… It’s just how people mount them.

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