Date:         Mon, 6 Aug 2001 14:24:22 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Expert Comment on the Turbo Oil Drain Delimma
Content-Type: text/plain; charset="US-ASCII"

At the gleeful risk of boring the great majority of list members out there, I
am moved to share some of my recent correspondence on the issue. As those of
you with a modicum of interest will recall, I'm grappling with the issue of
how to connect the turbocharger return line to the oil sump in my Audi 3A
project. Lacking extended responses from the list or several VW forums I
follow, I sent the following email to Corky Bell, author of the excellent
book on turbocharging "Maximum Boost":

I'm building a turbocharged Audi 3A 2.0L engine using the Bosch LH-Jetronic
fuel system, and the Garrett T3 with the complete SAAB APC knock sensor boost
control system (all taken from a '88 900 turbo. I plan to run the stock
10.5:1 compression ratio, limit boost to 7 psi max and will use an Audi 5000
intercooler. I am using the original Audi 3A high flow intake manifold, and
an exhaust manifold from a VW Quantum 1.6L TurboDiesel. I have fabricated a
stainless steel flange adapter to mount the T3 on the VW TD manifold. I'm
looking for a reliable 160 to 175 hp. All seems to be going well except for
one key flaw. I will be mounting the engine in my VW Vanagon (formerly diesel
powered) camper. The engine mount angle is 50 degrees from vertical as
compared to the typical VW mount angle of 15 degrees. Therefore, the problem.
The turbo oil return drain port gasket is at the same level as the top of the
static oil level in the pan. According to your book, this situation calls for
a scavenger pump to pull the aerated oil from the turbo drain and dump it
back into the crankcase above the oil level. I have contacted the suppliers
listed in the book for oil pumps and received the equivalent of audio shrugs
over the phone. Tilton Engineering makes a 12 volt pump, but claims mods must
be made to use it, but no details. I can find no trace of the oil pressure
driven scavenging pump you mention. I could sure use some leads here.

BTW, VW has mounted several different inline 4 turbocharged diesels in their
european models. I have the factory cross-sectional drawings. For the 1.6L
and 1.7L versions, the turbo is at the same level as my approach, and the oil
return line enters the oil pan about 22 mm. below the static oil level. The
line is long and nearly horizontal, and the internal diameter is right around
15 mm. For the 1.9L engine (later design), the turbo mount is about 1 cm.
higher, but the oil line makes an immediate 90 degree bend coming from the
outlet flange, goes up and away from the oil level in the pan, then takes an
other 90 degree jog down to the side of the block, where the oil enters above
the static oil level. Clearly this line must be full of oil. The oil head
level is at least 50 mm. So, all the factory versions violate your oil return
basic rules. Open to suggestions. Oh yes, when hot, the idle oil pressure
drops to 5 psi and runs roughly 10 psi per 1K rpm up to about 4500, were it
rests.

Enjoyed the book!

Frank Grunthaner

Corky just replied with the following:

Hi Frank,

You have found one of the overly conservative flaws in the book. I think your
drain will work okay. It is entirely possible to put the oil back into the
sump below the oil level. Somewhere in there is a judgment call, but I\'d say
your layout is worth a try and will, 9 out of 10, be okay. The difference, if
any, will show up down the road after 10\'s of thousands of miles, when a
slightly worn rear turbo seal may leak a little that would not otherwise if
it had 20 inches to drop to the oil level. Pumps are available, but lets work
that out if your system doesn't prove workable.

Corky

Other data:

I have now found 12 volt electrically driven scavenger pumps rated to handle
oil, high temperatures and continuous duty. Surprisingly, this problem must
be addressed by every turbo kit manufacturer for motorcycles and most of the
kit manufacturers supporting American V6 and V8 installs. Prices range from
$85 to $275. Information on request.

Frank Grunthaner