Increasing fuel pressure

[Steve Spiers]

Hi

Yeah I understand that, but I do not have full control. I want to run higher
pressure for extra boost pressure etc. The function is apparently not linear,
The whole sales point of these things is that it is rising rate and adjustable,
but there is no info on how adjustable or how what the rate is. Ive emailed some
people that have them and they have just fitted them without setting them up
etc! They just though that more fuel pressure would be obtained and that was
good! heh

If the fuel pressure at idle is a bit more, it would be ok as the AFM is
adjustable. I also have a larger AFM that I could use.

Im trying to do this by spending the least money. Ive tried bigger injectors,
but there is not enough scope to bring the mixture down at idle, I tried some
slightly larger injectors and this worked better, but the idle mixture is all
over the place. If I set it to about 1%CO it may end up as high as 7% after I
drive the car.

Thanks, Steve


Axel Rietschin wrote:

> What you want is maintain a constant relative pressure between the fuel and
> the manifold. Say your base fuel pressure is 300KPa. The regulator thus give
> you 300Kpa fuel pressure at 100KPa manifold pressure. At 200KPa in the
> manifold the fuel pressure will be 400KPa etc, in order to maintain the
> 200KPa differential pressure the injectors like to see. In this example if
> you have 50KPa manifold pressure at idle, the fuel pressure should be
> 250KPa, in short the regulator should follow the manifold pressure 1:1, that
> gives you one less thing (flow vs. MAP nonlinearity) to worry about when
> setting up your fuelling, assuming you have full control over it.
>
> HTH,
> Axel
>
> ----- Original Message -----
> From: "Steve Spiers" <s.spiers at xtra.co.nz>
> To: <diy_efi at diy-efi.org>
> Sent: Sunday, October 28, 2001 00:48
> Subject: Increasing fuel pressure
>
> >
> > Hi
> >
> > I want to install an adjustable rising rate fuel pressure regulator. There
> are a
> > few different brands, Malpassi, FSE etc. They all look the same and I
> think they
> > are just branded differently. I have access to a Malpassi.
> >
> > Anyway, I have not been able to find any information of how adjustable or
> how
> > much of an incresing rate they have. Ive calculated (guessed) that I need
> around
> > 5 bar fuel pressure at 30psi absolute manifold pressure. If it was set up
> like
> > this (if at can be) what does this give me at idle (20in/hg) and say 1 bar
> > absolute? I would assume the pressure at idle has to be increased
> somewhat, lets
> > say 10psi? At +10psi, there should be enough adjustment to achieve a
> correct
> > idle mixture, but if the fuel pressure has too much higher than that I
> think I
> > will run out of adjustment. Im not really a fan of adjusting the AFM
> spring
> > tention. Thoughts?
> >
> > Steve
> >
> >
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