Johnv

Ok just wondering if there would be any difference in fuel pump demand (reserve pump capacity) between running static 58 psi and 60# injectors (bosch 044 pump)
or boost ref, 58 psi base pressure running 12psi boost.

what i'm really asking is will either setup max out pump sooner
or will they be the same seeing as the amount of fuel passing through the injector should be the same even though at different pressures

assuming injector flow rate tables are set up appropriatly and VE dialed in

jstacy

As pressure increases flow decreases in the pump.

onfire

iTrader: (17)

Injectors flow more with more pressure (up to a point)

Pumps flow less with more pressure demands.

IF...big IF...the injectors will handle your above example running boost reference will max the pump out sooner.

But, by not boost referencing the pump, the injector will only see 46psi at max boost...really limiting the injector.

Bosch 044's are stout. I would boost reference it as it is less likely to run out of steam as quickly as the injectors will.

Johnv

Thanks,
Was pretty much what I was thinking.

At least boost ref will lower FP at idle and decell makes it easier to controll the #60s at low flow.

What if instead of running a base pressure of 58psi, it was dropped to 43.5 (3 bar) with boost ref, pump would only have to increase pressure to 55.5 psi at 12psi boost instead of 70psi with 58psi base FP so pump flow would not be reduced ?

Again I realise VE would need to be dialed in for the lower pressure.

Cheers
John

jstacy

No matter what you set the base at pump flow will be reduced when you boost reference and raise the pressure.

Johnv

Yes but if base pressure is lowered so max pressure pump will have to flow under boost, is the same as running an un referenced regulator at 58 psi, wouldn't pump requirement be similar at WOT !

onfire

iTrader: (17)

Pressure is pressure. If the pump is not referenced and set at 58psi the injectors will see 46psi at max boost.(pump holds at 58)

If the pump is set at 46psi and is boost referenced, the injectors will see 46psi at max boost.(pump ramps to 58)

I like boost only reference myself....no vac...Mototrons are great...set the pump to 58psi....boost only reference...and you have the best of what you have.

BlkHwk

iTrader: (8)

How does vac. affect the FPR? I was under the impression under normal vac. fuel pressure would stay @ whatever you set it @ static. And then raise @ a 1 to 1 ratio under boost. Is this wrong? I am completing installation of my new fuel system and haven't had a chance to play with it yet. Where are you getting boost only reference? Using a check valve or somethin.

Thanks

onfire

iTrader: (17)

Vac will pull your fuel pressure down under the setpoint. Say you want 58psi base and 1:1 under boost. If you have the FPR hose connected to the inlet pipe before the throttle blade it is boost ref only. Car will idle at 58psi and the fp wil rise 1:1 with boost. If you connect the hose after the throttle blade...say to an manifold tap...you will get a vac signal also...so you romove the hose , set the FPR to 58psi at idle...hook the hose back up and your fuel pressure will drop 1:1 based on the vac your motor is pulling... say 20"vac...fp will drop to 38psi......either install a one way check valve to keep vac off the fpr or install the tap before the throttle blade to get boost only.

BlkHwk

iTrader: (8)

Gotcha

I should have known better about setting the pressure without vac., as that's how all of the stockers I've dealt with work. This is the first aftermarket FPR I've dealt with tho. Thanks