Date: Thu, 30 Jun 94 17:57:10 CDT
From: William Kennedy
Reply to: vanagon@lenti
To: Multiple recipients of list < vanagon@lenti >
Subject: 6 cylinder Vanagon
This is a summary of how to put a carbureted Porsche six into an
aircooled Vanagon. It is presented as an aid to those who want
an idea of how difficult such a project is.
Buy a *complete* Porsche engine. The only parts you won't use
are the flywheel and clutch, and the muffler. You also need an
oil tank and two Porsche engine mounts. Get one that matches
your engine. Early ones had threaded hose connectors, later
ones push-on hoses, for the line from oil cooler to tank.
Flywheel and Transmission Mounting
You need a flywheel that takes the 228mm (9-inch) VW clutch disk
and pressure plate, but with a Porsche center to mate to the
Porsche crank. This one is easy, since you are unlikely to do
anything about it alone. Send your money to Kennedy Engineered
Products. FAT Performance resells the same part at the same
price if you prefer to deal with them.
Since the Porsche and VW transmissions have the same pattern of
mounting holes, the flywheel is the primary part needed for
mating. A minor problem is that the upper mounting bolts on the
VW are through-bolts that take a nut at the engine side but on
the Porsche engine the bolts screw right into the case. The
driver's side VW bolt is fine; it's even the right size. The
passenger side bolt needs to be replaced with a socket headed
bolt to clear the starter.
A slightly tougher problem is interference between the flywheel
and a mounting boss of one of the case sealing bolts on the
north side of the crankcase. KEP's flywheel is meatier than the
stock Porsche. You can request that KEP turn yours a little
narrower (the flywheels are not shelf stock -- they make them to
order) and/or you can grind away a little of the bolt boss. Use
a cylindrical grinding point, use a straightedge to make sure
you are grinding evenly, and don't go too far. Stop often,
mount the flywheel with 2 or 3 bolts, and see if it still binds.
The engine support for the Porsche engine requires that two
engine mounts be firmly supported south of the engine, in a spot
where the Vanagon doesn't have anywhere to hang them. Placement
is fairly critical, since the position of the engine mounts will
locate the engine both side to side and up and down. The third
point that locates the engine/transmission combination is the
front transmission mount, which is quite flexible and would
allow the engine to be mounted "wrong" by many inches each way.
I put a strong box-member (3-inch width, 1/4 inch wall,
aluminum) across from one frame rail to the other, and mounted
the engine mounts to it. The box member needs a long mail slot
cut in the bottom to clear the Porsche engine brace. Big
U-bolts hold the bar in place on the frame rails once you have
it located perfectly. This is the only "no-welding" solution I
could figure out.
Note that the engine/transmission combination is in line with
the car but offset over a half-inch to the passenger side, so
don't try to get the two sides even.
The Porsche six is a dry-sump engine; oil is stored not in the
crankcase but in a separate tank. The quantity of oil is not
3-4 quarts like the Vanagon 4, but 10-12 quarts. The good news
is that there is a natural space for the oil tank next to the
engine, very close to where it is located in a Porsche. The bad
news is that quite a large hole needs to be cut for the tank, in
the metal that makes up the south wall of the wheelwell and the
floor of the engine compartment, below where the FI box hangs.
This area gets spray from the passenger side rear wheel, so it
is not an area where you want your engine to be getting air.
Cut as close to the oil tank dimensions as you can, and seal
open areas with weatherseal when the tank is in. I made a
cardboard model of the area, and trimmed till it fit the tank
perfectly, then tore the model apart and used it as a template.
The stock VW accelerator cable is roughly correct for length,
but it reaches the engine on the wrong side of the car: The
Porsche engine expects the accelerator about 10 inches west of
the centerline, rather than east. To allow it to slant across
the bottom of the car, and up past the clutch cylinder, holes of
1/2inch or more diameter must be drilled in the front and back
walls of the cross-member that the transmission front mount
attaches to. Be sure not to nick the brake line in the course
of drilling either hole.
Once the cable reaches the west side of the engine, thread it
through the north engine sheet metal, and cobble it to the
carburetor linkage. I stole the appropriate part from an old VW
fuel injection and bolted it to the carburetor linkage. A less
neat but still effective hookup could be made by clamping the
cable to the carb linkage with hose clamps. While you're in the
area, get some WD40 or other lubricant, maybe with some
graphite, down the cable so it runs smoothly, since it now has
two new curves in it.
VW flapper valves are a tolerable, not perfect, fit on the
Porsche heat exchangers, and are located such that the stock
heater cables still work unless you break them getting the VW
Nothing tricky. Wire from Porsche alternator to VW starter and
red-dash-light wire. I am using stock Porsche distributor,
stock VW coil, and cheap J.C. Whitney capacitive discharge
Buy aftermarket oil pressure and oil temperature gauges, making
sure that they are correct for the Porsche senders. Put the oil
pressure sender on a tee so you can retain the VW oil pressure
light sender. You may want to get an oil level gauge and
connect it to the sender, but I've never had an oil level sender
that worked, so I ignored it. Check your oil with the dipstick.
Buy an aftermarket tach that works with your ignition. There
is nowhere on the VW dash to put the gauges so they look good.
Put them where they fit. Rich people put in a complete Porsche
dash cluster, but I wouldn't know about that.
Vacuum for Brakes
Probably you could get away with teeing together the vacuum from
the bases of two carbs. I have a fabricated vacuum box with
ports for seven hoses, so I take vacuum equally from all six
The air above and below your air-cooled engine (VW or Porsche)
should not mix. The air below is warmed by the exhaust and by
passing through the engine. The air below also has road dirt
and exhaust gases in it. The air above the engine is what cools
the engine, and what the engine takes into its carburetors. The
air above the engine is also what you breathe when the heat is
on. Again using cardboard templates, design additions to the
Porsche sheet metal, to reach within 3/4 inch of the walls of
the engine compartment. Then the stock VW airseal will work
fine. Tricky parts are at NW and NE corners, where the trim has
to turn a horizontal and a vertical corner in one smooth curve.
Look at the stock VW tin for ideas.
The stock Porsche muffler won't fit. It interferes with the
southernmost chassis crossmember. A Sebring muffler from
Performance Products will fit, but is very loud. I'm using the
headers from the Sebring, and a medium-sized muffler that slants
northwest from behind the engine. Still a little too loud, but
it's all I can fit in the space.
Replace the high-pressure FI fuel pump with a 2-4 psi Facet pump
appropriate to the carburetors. Drill one new hole so you can
use the same rubber mountings as the stock pump, or the noise
will drive you crazy.
Headroom for Carbs and Fanhousing
The MSDS kit recommends that you use the 3.2 and later engine,
which with some minor trimming will fit under the stock engine
lid. Less expensive Porsche sixes have taller induction systems
(2.4 to 3.0 liter CIS FI systems are tallest of all). Luckily
the area where extra height is needed is within the area defined
by the removeable decklid, so you'll just need to make your
decklid taller by six or eight inches, without affecting how the
decklid seals to the luggage floor around its perimeter. This
can be done with sheetmetal and pop-rivets, or by welding a box
on top. Either way, for good sound and smell insulation the box
should seal real well. If you want to be able to get back to
stock, get another decklid from a wreck and save your original
You have to decide whether it's worth it. I'd do it again in a
minute, and was pleasantly surprised that I and my ill-equipped
garage were up to it. I was prepared for the possibility that
I would have to put the VW back in and punt. But the problems
are all solvable and the big cost is right up front where you
can see it: a Porsche engine that in my case is worth as much as
the Vanagon itself.
Good luck to all those who take on this type of project.
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