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Subject:Progress on the fuel injector mod on Audi 3A Project
From:Frank Grunthaner
Date:Wed, 27 Jun 2001 21:00:45 EDT

To any who are interested,

In my switch to the SAAB Turbo engine management system for this engine, I
decided to use the 3A intake manifold as it looks to flow better than the
Digifant 8V head and manifold. This intake manifold has its CIS injectors in
the intake manifold right near the intake port, not in the head as per the VW
8Valve engines. I determined that the injector spacer distance was the same
as for the Digifant fuel rail, so I studied the possibility of making a
modified injector holder to convert from the CIS injectors to the
Digifant/Jetronic style injectors. The Audi manifold mount through a Bakelite
plastic O-ring sealed adapter necessarily gives cooler injectors and injected
fuel than the VW approach.

Success. I can email the interested a drawing of the cross-section of the
injector holder. The outer black outline is the external projection of the
Audi plastic injection holder. The blue dashed inner surface of the stock
holder. The red curve is the new cut which must be made. It is convenient to
drill the center hole to a depth of 0.650 inches with a width of 41/64 th's
(0.640 inches). This clears the main body of the injector. The 60 degree
chamfer can be done with a 1 inch 60 degree countersink. This lets the
injector sink down into the plastic holder. I will use an additional O-ring
on the base of the injector as a secondary seal for the system. Works
perfectly. Good seal. As noted on the PICT diagram, I cut off the injector
lower shroud to clear the spray pattern from the injector. Should increase
the port flow. Should take about 30 minutes to an hour on the lathe to
duplicate.

I am now looking at the Digifant fuel rail mount to hold the injectors down.
I have an adjustable fuel pressure regulator and adapter to interface to the
rail. I will also mount the sender for the digital fuel pressure gauge here.

Looks clean so far.

Frank Grunthaner

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