am i right that the more boost the more fuel pressure? and is there a calculation to what pressure should be at what boost?

 

On electronic injected cars, Fuel pressure does change with manifold pressure.

Fuel pressure changes in exact proportion to boost/vacuum.
(This applies to a normal fuel pressure regulator )
(FSE power boost valves raise the pressure more than boost.... crap IMO)

For example, on a cossie.... (and most electronic injected systems)

At 0 pressure (atmosphere) the fuel pressure should be around 3.5 bar / 52 ish psi.
This is called the base fuel pressure.

So on boost of 1 bar/ 15 ish psi, the fuel pressure should be 4.5 bar / 67 ish psi

Therfore also, under vacuum, the fuel pressure will go down.

The idea is that a constant pressure differential is applied across the injector
so the flow rate/spray pattern can be predicted/fixed.


As for mechanical injection (KE JET) S1/S1 escort,
usually the fuel pressure is constant and the flow rate is adjusted
by the airflow meter flap.

 

i think simon sums that up nicely

 

 

one point tho for simon, most FSEs are still a 1:1 rising rate... tis just they respond 1.7 times quicker (theyre not 1.7:1 rising rate)

some have different rising rates

 

i have a fse valve on me cossie

maybe that explains the loverly flames i get on over run

 

FSEs are 1:1 still, but Stu tested one once and it didnt stay at 1:1, so they a bit wank i think, or at least that one was.

SECS also mentions "on electronic injected cars", well it does on all factory carb turbo motas ive seen too, id guess most turbo engines really, i had no idea on mech inj RSTs it didnt change, in fact i thought it did!

Not like eithers relevant to the first question, but thought id mention it...

 

stsve, mechanical injection works well different to EFi...

you'd be surprised!

 

yes jim, shocked to the core, changed my life

carb turbos (well all ive ever seen) have rising rate regs tho.