V8 S/charged motor jet size?

[stevebez]

OK so planning a HFS-6 system for this motor.

8 injectors rated at 39lb/h (~409cc/min) at 3 bar, but fuel line pressure runs at ~ 70PSI -80 (so ~5bar), so flow perhaps well above 500cc I would expect, but difficult to know exactly - anyone know how to extrapolate this?

So if I am running (lets assume 500ccx8=>) 4 litres / min and running water only I should target an injector of 10% fuel flow giving me 400cc flow rate required.

Boost is at 29PSI (incl atmospheric), so net +ve boost of ~15psi (~1bar).

160psi less the call it ~30psi gives me 130psi net line pressure to feed 400cc flow so I need effectively one 0.8mm jet?

Am I on track or way off base?

Raising the FP from 3 bar to 5 bar should raise the rate from 409cc to 531cc. So 4228cc x 10% = 425cc Using the HFS-6 considering pumping losses and such, this is probably a .8mm or .9mm jet.

In you calc you only subtract the head pressure in the manifold, so 15psi, in reality it's not much difference.

[stevebez]

Many Thanks !!! And would you recommend two jets of 0.5 or just one of 0.8/0.9 ?

It depends on the piping and how you can fit the jets in the manifold. One bigger jet is less likely to clog.