[JakeG]

Do you really need a booster? It's just an extra reservoir to keep some
pressurised fuel, so that at a full flick of the throttle, the fuel
pressure doesn't drop much (sort of like a capacitor for a electric
circuit).

You can do the same with your own reservoir. Just include a small 100cc
tank into the pressurised circuit and fill it 1/4 full with fuel. (must be
pointed upwards so the air bubble is trapped.

[Phibes]

Ok sounds interesting.. and would like to know more.. about this and your
other DIY idea's, but I don't have a fuel delivery/supply problem.. what I
have is a lean condition created by unmetered air entering the intake. This
is because of some air injector products I am trying out. Also I have an
agressive timing advance mapped that I would like to sustain without the
use of octane boosters.. so I am looking to "wet" this a bit.

Been doing allot of research in the area of fuel injectors and realise the
simplest method to overcome the side effects of some of the things I do is
to have an adjustable fuel pressure regulator, or to have a box with a
range of FPR's at 3, 3.5, 4, 4.5, 5, etc.. but after spraying fuel over
everything and almost cracking the fuel rail in removing and replacing the
valve,... I think an adjustable one with a meter will be much more
practical. What do you think?

The injector is a very high precision device.. yet it is still pretty
elementary in its design, the amount of fuel that goes through it when the
needle lifts is determined only by the amount of pressure on the fuel..
there are other factors to consider and in actual fact instead of changing
the FPR, it would be best to change the injector and FPR to sustain the
optimal spray pattern while increasing the flow rate .. but thats not in my
budget for testing/trial and error.

Consider that Bosch makes over 1100 different injectors.. of which at least
100 would fit your car.

So who could recommend the best/ affordable brands of Japanese or other
Booster or Adjustable FPR's? Does anyone make an Adjustable Booster type?

[drexchan]

Hi guys,

which mod do you think is more practical?

1. replacing the stock FPR with an adjustable after-market unit -
basically playing around with the valve opening by restricting the return
fuel.
2. use back the stock unit but play around with the FPR vacuum hose to
get a higher manifold pressure reading than actual.

your opinion? thanks in advance.

[JakeG]

Hi Chappies..

Phibes, I only know that Alex of everauto do the installations, but not so
sure about the source/brand. Have you tried one of the japanese suppliers
for Honda/ Mitsubishi engines?

Drex,

1) An adjustable one is definitely better if you have a straighforward
vehicle and you want to play around with richer mixtures. However in on
Bosch closed loop systems, when you increase the pressure the ECU will re-
compensate by decrease the injection timing to arrive at the correct
stoichiometric..so you're back to square one.. unless you can fool the ECU
with a piggyback or augment the oxygen sensor voltage.



2) You can't really play around with the vacuum tube/diaphgm as the range
is only -0.4bar to 0 bar trim on the main fuel pressure... that's a too
tiny range to play with. You can try putting PRESSURE instead of
connecting to vacuum but a way to vary the pressure to reflect the
manufold vacuum must be found.. lots of trouble. Bear in mind that this is
to trim the differential pressure between fuel line and injector tip.. and
if you remove the trim, your metering will suffer.

Please do note that some injector pistons and needle will NOT open under
too high pressure... There are loads of injectors out there with different
spray patterns and flow rates..

[drexchan]

JakeG,
Thanks for pointing out the technical issue. Will take time to digest.


Actually i have regreted to invest RM100 in that stuff under my bonnet. [:
(]

[JettaMk3]

Also... can we swap in Japanese injectors into our cars? I just wann afind
out the original flow rates and get somethign a bit bigger...

[Phibes]

Ya man.. I was at the half cut shops yesterday.. with the same question in
mind - all the Denso ones I seen don't have the Bar Pressure stated.. only
the part numbers.. I seen older Toyota engines with Scew ajustable FPR's
but again no indication of ratings.. I did find an insert type from an
unknown engine.. but it was a 3 Bar .. as far as getting one of these
Japanese types to work.. I am pretty sure it should work as they all do the
same thing the same way and can be cable tied in place. I am considering an
After market fuel rail in the future to eliminate the push in cradle we
have. Can you find a Denso FPR reference chart?.. I havn't been able to so
far.. but will keep looking.


Phibes

[JakeG]

Phibes... you're talking about the air bleeding mods under your hood
(RM100)? Jeeze.. my friend did the same mod with some aquarium tubing, one
way check valve & adjustable valves, although I'm doubtful whether leaning
out the mixture works.. Check out the car modifications thread for more
info on DIY air bleeding.

Jetta.. you need to know some injectors must have an inline resistor to
reduce the current. I'm not so sure what Bosch system setup is, but
assuming you can get the right match both on the coil winding rating, the
nozzle sizes, then yes you can use japanese ones ( I tend to believe the
jap injectors are quieter).

[Phibes]

Jatta, sorry dude in my last post thought you were talking about FPR's..
see now you were talking about injectors... in this catagory I am not
sure.. but it can all be referenced easily once you have the Part numbers
for yours.. I have a good list Injectors and their specs.

Jake will read more on "Air Bleeding" thanks.. actually I am lean, but I
don't want to be so lean.. the Air Injectors I am using are good and they
serve a good purpose for me.. that is I have eliminated the stock air
intake tube with a nice 3" aluminum tube with no holes or tubes in it.. and
they are adjustable.. and atomize the mixture better.


now I need to enrichen the mixture on a full time basis equal to compensate
for the air.. the reason I know that I can do this with a FPR is because my
Last FPR went Kaput.. and raised to 6 Bar .. this made my Plugs black and
fuzzy and I was super rich for about 4 days.. the ECU never did compensate.
. as I guess it had no way to Logically do so and still keep the car
running.. so I am back to the plan.. uprate the FPR to compensate for the
lean condition caused by the unmetered air (air that is not being sensed by
the MAF)


Peace

[JakeG]

Phibes.. is there a way to connect a tube nipple to your push in adapter
under the FPR? Doing so, you can forget the push in type, connect a hose,
and connect to a FPR mounted neatly on the firewall.

For those who are thinking of this... FORGET it coz I've tried it..
putting two FPR's with same pressure bleed in series WILL not increase the
fuel line pressure, as the FPR will both bleed at the same pressure. But
if you put one 3bar and a 4bar one, the fuel line pressure will only reach
to 4 bar.