Date:         Tue, 7 Aug 2001 15:43:38 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      New Milestone in the Turbo 3A Project
Content-Type: text/plain; charset="US-ASCII"

Ah, the arrival of a new day (several hours ago), sweet with the satisfaction
of a long standing struggle resolved. Victory. The essence of the unscheduled
breakthrough.

No, I'm not talking about losing 20 pounds, or even achieving the delicious
image of a set of under 40 nubile maidens running their hands through my
unimpressive silvery locks rapturously following my every word on my
soliloquy on the rate limiting step of carbon compound solid state oxidation
in the absence of water on Mars. This milestone relates to the three
dimensional understanding of the oil pickup tube location in the vanagon
diesel (in-line 4) configuration.

Let me begin again. Many years ago, when I first took apart the Vanagon
diesel engine and the 8V GTi RV engine for essential parts swapping, I
noticed the unique design of the Vanagon D oil pickup. Sort of resembled (to
me) the classic image of the discus thrower on ancient Greek pottery after
the throw. Upon cleaning them both, I noticed the plebeian nature of the gas
engine (RV) unit as compared to the diesel pickup. Frankly, several things
bothered me about the elegant diesel unit, but I couldn't quite focus my
thoughts. Later, following years of frustration with low oil pressure and
blinking oil lights following vigorous charges across the SoCal speedway
system, I resolved to go to larger gears and a stronger pump.

Mind you, the original diesel oil pump had shorter gears than the RV engine
equivalent, so I thought I was already moving more juice using the RV oil
pump body with the CS diesel oil pickup. Well, as all the initiated acolytes
on this list are well aware, the best (read highest volume flow) oil pump VW
has provided for their 2.0 liter engines is the 36 mm gear pump originally
brought out for the Audi 3A series, then later added to the 2.0L ABA 8V gas
block. Further, in the tradition of VW's better approaches to the engineering
art, the pump is retrofittable to all 1.8L blocks. Indeed, VW in-line 4
affectionados worldwide have been switching in droves to this pump to solve
their oil pressure woes.

OK, so I lay in wait at my friendly VW heavily used parts place and,
following the entry of a still smoldering A3 Jetta, I had pump and pickup in
my slimy hands, $25 poorer. Well, later that evening (after SWMBO had retired
peacefully), I had the three pumps on the bench for a touchey-feely. There
were a couple of interesting differences between the 36 mm pump and the
others:

First, the oil pressure relief system was significantly larger in piston
diameter and stroke.

Second, the internal diameter of the oil pickup tube was also much larger
(for the 36 mm gear pump).

Finally, the trapped oil level (volume) in the end of the oil pickup was
nearly twice the size of the diesel.

For many hours (days actually), I tried to come up with a way to modify the
36 mm pickup for use in the vanagon configuration. Nothing. Gave up and
bolted the diesel oil pickup to the 36 mm pump body. But now, under
irreproducible conditions, I find the pump losing prime before startup.
Uncomfortable 2 to 5 seconds results before all is well.

In the course of my 3A turbo project, I resolved to get the oil pickup
situation under control. Then, last night, Eureka! Breakthrough. Its done!

I set up a 3D jig to follow the tortuous path to the pickup face of the
diesel unit. Then bolted up the 3A 36 mm gear pump pickup. Turns out that a
Moroso Chevy small block oil pump pickup (looks like a small rectilinear
jewel box (25 x 25 x 75 mm approximate dimensions)) silver soldered or welded
to a 90 degree reducing union will bring the two components into harmonious
union. The current oil pickup (diesel) sits in the dead center of the cast
aluminum oil pan. It is mounted so that the base cover is mounted about 10 mm
up from the floor of the oil pan. This is surprising in that the generally
agreed upon optimal position of the oil pickup surface is 6 mm above pan for
most racing (high stress) applications.

The oil capture volume in the Chevy pickup is 2 or 3 times the VW standard
and at least 4 times the volume for the diesel pickup. Further, the pickup is
about 3 times longer than wide. In American circle track stock car
applications the long axis is mounted perpendicular to the long axis of the
car so centripetal sloshing will have the least effect on the oil pickup
volume.

Of course, this means that the original tube must be cut off. The cut is
simple and flat at the beginning of the curve. The interface between the
Moroso pickup and the VW/Audi one is a 90 degree reducer. I went to stainless
and will weld the final fitted components, but a common copper one will work
nicely, and could be silver soldered to the steel tubes.

Interestingly, the Moroso feed line is 3/8 inch tube, while the VW pickup
tube is 1/2 inch. The Moroso system uses constant diameter tubing, while VW
uses a crush tube bend approach which reduces the flow cross-section to
something comparable to the Moroso part. The new (modified) pickup will have
one additional 90 degree turn in the line as compared to the original, so the
pressure drop across the pickup tube should be somewhat greater. I'm assured
by several engine building acquaintances that the Chevy oil pump is flowing
more than twice the volume of the VW pump ("on a bad ass Sunday" they said
... ?..) so I'm not concerned about capacity.

The new arrangement will properly match the oil pressure relief system to the
oil pump (using the correct base now) and will have a much higher buffer
volume (minimizes air pickup st the head) and should retain prime much better
(more oil has to go out of the oil pickup column than before to break prime
at the gear inlet).

So that's my story for today. Think I'll have some soy sauce for lunch to
work on the uncontrolled girth growth factor.

Frank Grunthaner

PS. Remember, you could have deleted. Oh, yes, for the politically correct,
the starting paragraph was purely an ethereal image. No nubile under 40 year
olds were exposed to Mars oxidation pathway lectures this week.