[s-cars] FPRs & squirts

[Robert Pastore]

I had this argument with John Petersen, called up both RC and Marren to
confirm, then had to humbly admit defeat.   I had thought the increase FP
would result in an increase in fuel delivery.   It turns out that the
increase in opposing ( Manifold) pressure exactly offsets the increase in
fuel pressure.   While at first this might not seem intuitive,  i.e., the
compressible nature of the gas versus the non-compressible nature of the
pressurized fuel, if you
can accept the notion that the injector would flow more into a vacuum, then
it's not hard to see why it would flow less in an increasing pressure
environment.

So in the AAN setup, the pressure Delta between fuel and manifold is held at
a constant(= to FPR rating) , and the net fuel delivery remains the same for
a given injector pulse duration.

Bob




-----Original Message-----
From: Frank Amoroso [mailto:FAmoroso at svbank.com]
Sent: Wednesday, May 15, 2002 12:42 PM
To: 'Robert Pastore'
Subject: RE: [s-cars] FPRs & squirts


Can you explain how the increase in fuel pressure under boost is offset by
the increase in manifold pressure?

Seems to me that the line going to the FPR is adding boost pressure to the
top chamber of the FPR?

Frank--

 -----Original Message-----
From: 	Robert Pastore [mailto:rpastore at animalfeeds.com]
Sent:	Wednesday, May 15, 2002 10:37 AM
To:	'Frank Amoroso'; 'kirby.a.smith at verizon.net'
Cc:	's-car-list at audifans.com'
Subject:	RE: [s-cars] FPRs & squirts

Frank:

Per my Audi Motronic Training Manual under "Engine Changes - 20 Valve Turbo
AAN Engine", among other things is states "New Fuel Pressure Regulator, fuel
pressure increased from 3.5 bar to 4.0 bar" and "Four-hole injectors for
increased fuel flow".   Does this mean that the 3B was 3.5 bar and not 3.0
bar, or is the manual wrong? Can anyone confirm?

Also,  as Tom Black suggested, the increase in fuel pressure under boost is
offset by the increase in manifold pressure, resulting in no incremental
change in fuel delivery.

regards,
Bob





-----Original Message-----
From: Frank Amoroso [mailto:FAmoroso at svbank.com]
Sent: Wednesday, May 15, 2002 11:27 AM
To: 'kirby.a.smith at verizon.net'
Cc: 's-car-list at audifans.com'
Subject: RE: [s-cars] FPRs & squirts


My understanding is that patterns are stable down to 2.0 Bar. That being
said though, there is something about running higher pressures (rather than
lower) and better fuel atomization that will better serve my needs. That
being said, the RS2 injectors will be far too large for my purposes, think
of what they will be flowing when you add manifold pressure on top of the
FPR's rating!!

Anyone know for a fact how many spray holes the 3B injector has? My records
show 3 (like the AAN?), but I have never physically inspected one.

Frank--

 -----Original Message-----
From: 	Kirby Smith [mailto:kirby.a.smith at verizon.net]
Sent:	Tuesday, May 14, 2002 9:42 PM
To:	Frank Amoroso
Cc:	's-car-list at audifans.com'
Subject:	Re: [s-cars] FPRs & squirts

Is the spray pattern the same for an ADU at 3 bar vs. an AAN at 5 bar?
Looks like the ADU would provide the best headroom, but maybe idle
control would be difficult.

kirby



****************************************************************************
*******
This message contains information from Silicon Valley Bank which may be
confidential and privileged.  If you are not an intended recipient, please
refrain from any disclosure, copying, distribution or use of this
information and note that such actions are prohibited.  If you have received
this transmission in error, please notify the sender immediately by
telephone or by replying to this transmission.
****************************************************************************
*******


_______________________________________________
S-CAR-List mailing list
S-CAR-List at audifans.com
http://www.audifans.com/mailman/listinfo/s-car-list