RE return to fuel tank

[Greg Hermann]

>Hi all
>
>If you just want power then forget returnless fuel systems, you have
>nothing to gain except unwanted complications.  The automotive industry
>is having to use RFI systems as one way to comply with future
>legislation regarding Emissions.
>
>The original system works and has two major advantages
>
>1)  You get no pulsating pressure waves in the fuel rail, these cause
>the A/R ratio to
>      weaken.
>
> 2)  No aeration problems, air cannot get trapped in the fuel rail.
>
>  These problems have been experienced on engines running RFI during
>dyno testing.
>
>
>                            best wishes Roy

I agree completely with what you say, Roy, BUT:

I still maintain that combining a pwm control of voltage to pump (which
follows an engine load/speed matrix) with a conventional regulator and
return line would work better still. More complicated, yes, but better pump
life and better pressure control would both result. Next step one should
consider is the idea of putting float vents on the (tops) of the fuel rails
so as to make absolutely sure that no vapor ever collects in them or gets
fed into an injector. If one chooses to go with a two (pressure) stage fuel
system (best of all), a positve displacement, gear type mechanical pump is
well worth considering (the  volume of fuel available from one of these
will track engine speed with no further ado, plus you lose a large chunk of
electrical overhead by going this way. Drives for such pumps are
commercially available, as are gear type pumps which are hard anodized and
coated with appropriate polymers on the inside parts.

How much of this stuff you do all depends upon the sincerity of your need
for speed, and upon how much you have invested in your engine, as well as
upon how much you are willing to spend to protect your investment--sorta
like buying insurance, only more fun.

Regards, Greg