Love This

[Greg Hermann]

>-----Original Message-----
>From: James Weiler <james at brc.ubc.ca>
>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>Date: Friday, January 29, 1999 1:07 AM
>Subject: RE: Love This
>
>For me it's not the plumbing that is the "news".  It's being able to
>manipulate
>fuel line pressure without needing a mechanical device.  As things sit now
>for TPI the fuel pressure is referenced to engine vac/boost.  With this
>device
>a closed loop electrically controlled Fuel pressure trimmer is possible,
>meaning
>big injectors, lower pressure at idle, to help get reasonable pulse widths.
>Bruce

Hey--if you wanna do it right--use a rising rate regulator IN COMBINATION
with a pwm voltage control to the fuel pump AND a calculated fuel pressure
correction to the injector pw calc. It would hafta be a primary--secondary
fuel pressure control loop to be stable--program what the fuel pump is
supposed to do according to load/rpm ()with a look-up table), let the
rising rate regulator fine tune the rail pressure (it would be A LOT more
accurate cuzza bypass flow rate being nearly constant), AND also use your
rail pressure input to apply a calculated correction to the injector pw on
the fly. Doing these things in combo would prolly improve the accuracy of
the fuel quantity delivered to the engine by at least 2 or 3%, particularly
under transient conditions!!

Also, you will NOT lose the DISTINCT ADVANTAGE of having some fuel
recirculating through the rails--to keep them cooler--this way. Methinks
that the GM comments about less emissions have only to do with keeping the
fuel TANK cooler and keeping the evaporative problem smaller by doing so.
If you get vapor in the rails--it has to either go through the injectors or
back to the tank--no where else it COULD go. And--IMHO--if it goes thru the
injectors, it will give you a lean episode, and a stumble at best, or, more
likely, a detonation episode. Fact is--I believe in putting a float vent at
the high point of the fuel rail plumbing, so as to be SURE that all vapor
goes back to the tank, and NOT into the injectors.

Regards, Greg
>
>
>>Sorry to get in this late but so what?  I mean whats the advantage of >a
>one line EFI vs. 2 fuel line set-up?  Besides less plumbing.
>>thanks
>>jw
>>