[Diy_efi] Fuel Pump speed controller

[Bruce]

  I'd be interested in seeing if they use rather large or small fuel rails,
and if they aren't in some fashion doing the Hot Fuel Thing of the Honda F1s
of years ago.
  The Rally cars worry about emissions?.
  It's be so much easier if *we* didn't have all this low speed stuff to
dance with.
Bruce




----- Original Message -----
From: "efi_student" <efi.student at sbcglobal.net>
To: <diy_efi at diy-efi.org>
Sent: Sunday, August 04, 2002 2:36 AM
Subject: RE: [Diy_efi] Fuel Pump speed controller


> Maybe not so dumb.  Toyota is using a returnless system on their Group A
> rally car.  From someone very close to the source:
>
> "The reasoning is, its easer to keep the fuel pressure controlled
> without all the changes in engine temp in the mix. Also the controlled
> fuel evaporative keeps the fuel not only cool but in a controlled
> condition, this also helps with tuning and better mapping across the
> board, as the fuel is not all over the scale in temperature. Another
> benefit is weight, far less plumbing in the car no return line, no
> evaporative lines and fittings, evap tank separator its all gone one
> neat compact unit in the tank looks after all including fuel pressure."
>
> Initially I would have agreed with your analysis, but there is certainly
> something to be said for stable fuel density.  Having come from vacuum
> systems and gas control devices, I have always thought the method of
> controlling fuel pressure pre-regulator a bit at odds with industry best
> practice for gas systems.
>
> Lance
>
> -----Original Message-----
> From: diy_efi-admin at diy-efi.org [mailto:diy_efi-admin at diy-efi.org] On
> Behalf Of Greg Hermann
> Sent: Saturday, August 03, 2002 11:14 PM
> To: diy_efi at diy-efi.org
> Subject: RE: [Diy_efi] Fuel Pump speed controller
>
>
> At 12:40 AM 8/4/02, Scott F. Williams wrote:
> >Please educate me as to why you'd want to control the speed/output of
> >the fuel pump. Isn't the fuel pressure regulator the proper way to
> >control the pressure to the fuel rail, etc? I'm obviously missing
> >something here...
> >--
> >Scott F. Williams
>
> If he's talking about a non-return fuel system, would be one reason, but
> that is really a dumb design for performance use.
>
> A better reason is that two controls over a variable will give a MUCH
> tighter, more accurate control over the controlled variable--in this
> case fuel rail pressure.
>
> Kind of like the way heavy trucks use a thermostat AND (sometimes)
> radiator shutters AND (occasionally) a variable pitch cooling fan to
> control coolant temp.
>
> Greg
>
>
>
>
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