simple question about fuel press. regs.

[Bruce Plecan]

From: Clare Snyder <snyder at huron.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Tuesday, March 31, 1998 11:25 PM
Subject: Re: simple question about fuel press. regs.


>Bruce Plecan wrote:
>>
>> -----Original Message-----
>> From: TWright669 <TWright669 at aol.com>
>> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>> Date: Tuesday, March 31, 1998 2:25 AM
>> Subject: simple question about fuel press. regs.
>>
>> >Does the manifold referenced regulator inject the same amount of fuel
per
>> >milisec. over the range of manifold pressures?  After all, for every 1
psi
>> >increase in manifold pressure there is 1 psi increase fuel pressure,
which
>> >cancels out. Right?
>>
>> That's been my experience
>>
>> >A person who has a constant pressure fuel reg. has to do extra calcs. to
>> >figure in the effect of manifold pressure for the rate at which the
>> injector
>> >injects fuel, where as I dont have to bother.  Right?
>>
>> I took a system that had a fixed FPR, and went to vac ref., and it
>> was easier to dial in, and much more stable for AFR
>>
>> >Thanks,
>> >Tom
>>
>> Cheers Bruce
>The compensating, or variable, fuel pressure regulator has only one
>purpose in life. To make it easier to control fuel delivery over a wide
>range of manifold pressures. A properly designed MAP controlled system
>"can" get away without this mechanical complication, as it already knows
>the manifold pressure and "can" compensate for it. I emphasise "can"
>because not all do. A mass air system cannot readily compensate, and
>therefore almost requires the compensating regulator.
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This "trick" really works well for big cammed TBI's, with big Injectors.
I just gives more range.  Use two regulators actually, one to clip
WOT.      One regulator vacuum referenced, one to atmos
No worries mate
Bruce