CIS fuel pumps, how much HP?

[Jim Green]

--- JShadzi at aol.com wrote:
> BTDT many times on Audi applications with 2 pumps,
> never any problem you describe, though I could see
> how it can happen.
>
> Javad
>
> >I would add one caveat. You can get too much fuel
> volume for your fuel
> >pressure regulator to handle at idle. Since the
> engine does not use much
> >fuel at idle most of what your pumps will be doing
> is recirculation the fuel
> >through the system and back to the tank. We ran
> into this on a 911 turbo
> >project car (428 hp on an engine dyno). MoTec
> fuel/ignition running 2 fuel
> >pumps to insure enough fuel under full load at high
> rpm. The fuel pressure
> >would creep up at idle causing and overly rich
> condition. We had to add a
> >second pressure regulator and return line to
> control it. Maybe we went a
> >little over board on fuel pump sizes but we never
> had a lack of fuel.
> >Jim
> >1984 4kq
> >1985 4kq
> >
> >-----Original Message-----
> >From: JShadzi at aol.com [mailto:JShadzi at aol.com]
> >Sent: Tuesday, November 26, 2002 11:28 AM
> >To: jeg1976 at yahoo.com; quattro at audifans.com
> >Subject: Re: CIS fuel pumps, how much HP?
> >
> >
> >IME, the CIS3 pump is good to 400hp safely, I just
> replaced my 15 year old
> >CIS3 pump recently because I was getting some fuel
> cut out at 20psi and race
> >gas (350+hp I'd say no problem, considering I have
> about 300 at 15psi),
> >swapping in a S. African CIS truck (Eurovan) pump
> seemed to do the trick,
> >its the same diameter as the CIS3 pump, but 1"
> longer, a real hog, got it at
> >Eurospec a way back, no more cutting out.
> >
> >Anyway, you can't go wrong with 2 pumps, maybe a
> little overkill for 350hp,
> >just keep an eye on your fuel pressure, if it drops
> at max power, you know
> >you need more pump.


Yea, it shouldn't be a problem, I have an SX
adjustable regulator that should be up to the job.

Thanks,

=====
Jim Green
'89 90tq 034EFI, Haltech IG5
http://www.geocities.com/jeg1976/car_home.html

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