Turbo Diesel Vanagon

VW Autoist, March/April 1987, page 24-25.
The Oil Burner (column by Roland Walkenhorst)

Henry F. Dunlap of Wimberley, Texas, is another guy who was dreaming last year of owning a turbo-diesel Vanagon. Henry had an advantage, though. He already had a naturally aspirated 1982 diesel Vanagon camper when he got the idea that a blown oil burner might haul a van around quite nicely. "The camper is great," he wrote, "but the diesel engine doesn't give it enough power to accelerate safely in some situations, such as getting onto freeways or in critical passing situations."

Henry explored several possibilities, including adapting the VW parts from a late-model factory-turbocharger diesel. He eventually settled on a turbo kit from Arkay Engineering (15828 South Broadway, Gardena, Calif. 90248). This is the same company from which I once bought a turbo kit for my 1978 Rabbit diesel.

The kit cost $2,100, not including installation, compared with less than $1,000 for my Rabbit kit in 1979. I was a little surprised at the big increase in cost until Henry sent me the details of what the new Vanagon kit includes that mine didn't.

The most important addition is an air-to-air intercooler, a small heat exchanger that cools air from the turbocharger before it enters the combustion chambers. Intercoolers, mostly the water-to-air type, have been used for ages on truck engines but have just recently become popular for cars. A turbocharger's compressing of the intake charge makes the air going into the engine very hot. Cooling the compressed air by routing it through the intercooler results in a denser charge and increased efficiency.

Also included in the new kit is a trap that catches oil from the cam cover breather and lets it drain back into the oil pan. The oil would otherwise collect inside the air cleaner where the oil-laden air from the breather ren-enters the engine. My Rabbit kit just routed this breather hose into the intake pipe connected to the turbo. Oil blown out the breather would run down and leak out where the pipe connected to the compressor housing, resulting in a little oil puddle everywhere I parked. It look like Arkay has found a good fix for this problem.

The Vanagon kit also includes a new muffler and mounting hardware. Instrumentation is more complete than it was in my Rabbit kit. Henry's kit includes both a boost gauge and a pyrometer, an instrument that measures the temperature of exhaust gases coming out of the engine. Mine had just a boost gauge. Since high exhaust temperature indicates that the engine is being pushed so hard that fuel is continuiing to burn after it leaves the cylinder -- an inefficient and possibly damaging situation -- the pyrometer can help the driver refine his driving style to get better efficiency and engine longevity. Pyrometers are used extensively in trucks for that reason.

Henry is well pleased with the workmanship and performance of the kit so far, although he had some trouble with delivery. It took two months for the kit to arrive and when it did, three heat-resistant silicone hoses for the intake plumbing were missing. After numerous phone calls to Arkay resulted in unfulfilled promises to ship the missing parts by UPS air, Cal Triesch of Crestwood Motors in San Marcos, Texas, the mechanic who installed the kit for Henry, gave up hope of getting the parts. He made do by using the silicone hoses that did come with the kit for the hotter parts of the installation and conventional radiator hose for the rest.

Next time we'll get into some of the details of installing the turbo kit on the Vanagon.

VW Autoist, May/June 1987 page 22-23.
The Oil Burner (column by Roland Walkenhorst)
Amateurs, Get Help

Installing the Arkay turbocharger kit on a diesel Vanagon is, in theory at least, a fairly simple job. Even so, I wouldn't recommend that an amateur mechanic go it alone if his mechanical experience has included only simple maintenance tasks.

Henry F. Dunlap, whose Vanagon we featured in the last issue, enlisted the services of professional mechanic Cal Triesch for his installation. When I put an Arkay turbo kit on my Rabbit a few years back, I also had a lot of help from professionals, including the use of their hoist for easy access to the underside of the car.

The Vanagon installation includes drilling some holes in the vehicle, including one 7/8-inch hole in the oil pan. A screw-up here could prove expensive. Problems might also arise when disassembling the exhaust system, an operation often made difficult by rusted fasteners. In short, think twice before tackling this job by yourself unless you're an experienced mechanic with the proper tools. And in any case, be sure to allow plenty of time for the job.

The first step is to take inventory of your parts to make sure none are missing from the kit. The first parts to come off the Vanagon are the bottom engine shield, exhaust system (not including the manifold) and the air filter container. The line that feeds the boost gauge is then connected to an existing hose at the intake manifold by cutting the hose and inserting a special fitting.

Next comes the job of cutting that 7/8-inch hole in the oil pan. This is where the oil that lubricates the turbocharger bearing will run back into the pan. Once the oil is drained and the pan removed from the engine, the hole is drilled in the spot pinpointed in a drawing that comes with the instructions. Fortunately, the pan on the Vanagon is cast aluminum and is easy to cut. Care must be taken, however, to get the hole perfectly round and remove any burrs caused by the drilling.

The fitting that goes in the hole will be sealed with an o-ring and if the hole is egg-shaped or has jagged edges, an oil leak is likely. If you don't have the tools to make a clean, round hole, it might be best to let a machinist to it. With the hole finished, the drain fitting is installed in the hole and the pan put back on the engine.

Now you're ready to bolt on the expensive part, the turbocharger itself. The turbo comes from Arkay with a "J"-shaped pipe already attached to it. The "J" pipe is bolted to the existing exhaust manifold. A tubular support brace is then fastened between the turbo and the transmission. This brace helps support the unit and takes some of the strain off the exhaust manifold studs.

The oil drain plumbing is next. The Arkay oil drain box is bolted to the side of the cylinder block and hooked up to the turbo and oil pan drain fitting installed earlier. The new muffler is mounted next. Then it's connected to the turbocharger using the turbine exit pipe supplied with the kit.

A new air inlet box is then fitted to the stock inlet manifold. A flexible hose connects the turbo inlet to the air filter box. The oil supply line for the turbocharger is installed next by removing the oil pressure gauge sender from the cylinder head and replacing it with a "T" fitting that comes with the kit.

The instructions don't mention it, but it seems this would be a good time to squirt a little clean motor oil into the turbocharger bearing so it won't be completely dry when the engine is fired up for the first time. The turbo oil line is attached to the turbo bearing on one end and the "T" on the other. The gauge sender is then reinstalled in the remaining hole in the "T".

Mounting the intercooler requires drilling a hole in the Vanagon's left chassis frame rail. A drawing shows you where. Once the unit is bolted in place, several pieces of hose are used to connect it to the turbo's compressor outlet and to the intake manifold by way of an adapter box.

The pyrometer (exhaust temperature gauge) sending unit is installed in the exhaust "J" pipe next. Now both the pyrometer and the boost gauge can be installed on the dashboard and wired for light.

Next, the cam cover breather is connected to the breather can, the oil drain box, the air filter box and the engine block with a complex- looking array of hose. The purpose of all this plumbing is to let oil that blows out of the breather drain back into the crankcase instead of accumulating in the air cleaner.

The installation is completed by replacing the air filter element and filling the engine with CD-rated oil. CD oil is formulated for severe diesel service and should always be used in a turbocharged diesel instead of the CC oil recommended for naturally aspirated diesels.

Arkay recommends resetting the injection pump's fuel delivery to match the increased amount of air the turbocharger pumps into the cylinders. This is a simple but touchy adjustment that, if overdone, can result in a smokey, inefficient operation. Keeping an eye on the pyrometer and exhaust smoke will help determine the correct setting. The more fuel you pump into the cylinders, the hotter the engine runs. Arkay recommends a fuel delivery setting that produces a puff of black smoke at each gear change and "just a wisp" at cruising speed.

Henry has promised to keep in touch, so we'll give you an update once he's had a chance to thoroughly evaluate his boosted Vanagon's performance.

< picture captions >

"The turbocharger is bolted in place on the Vanagon engine. The "J" pipe with the pyrometer unit installed is beneath the turbo. The right part of the turbo is the exhaust turbine and the left part the compressor. The oil supply and drain pipes are attached to the center of the unit."

"A rear view of the Vanagon showing the exhaust pipe leading from the turbo to the new muffler. Also visible are the black oil drain box and the oil pan with the turbo oil drain line installed."

VW Autoist, July/August 1988, page 25-26.
The Oil Burner (column by Roland Walkenhorst)
Vanagon Turbo Revisited

It's been more than a year since we last checked in with Henry Dunlap, the proud owner of an aftermarket turbo diesel Vanagon in Wimberly, Texas (March/April and May/June 1987 Autoist). As he promised, he's kept in touch with occasional reports of the boosted van's performance. He's also added an air conditioner to cope with the long Texas summers. I'll let Henry do the talking:

"We sneaked away for three days and took a trip in the van to Rockport-Port Arkansas area of the Gulf Coast. The van performed very well, I thought, both in the hill country and in the flat coastal plain. You have to drive with more of an eye on the pyrometer than the speedometer, as the temperature can quickly exceed the 1,200-degree limit while going up a hill if you don't. Letting up on the accelerator or downshifting drops the temperature quickly. The 'feel' of the van is definitely improved by the turbo. It's certainly not a hot rod now, but it's not a turtle either. Fuel economy was good -- 26 mpg driving at around 55 mph on the 460-mile round trip. I couldn't detect any oil usage.

Cal Treisch (the mechanic who assisted in the turbocharger installation) worked out the air conditioning installation. It cools the van nicely, and there is no sign of engine overheating when the air conditioner is used. He used a compressor from a VW Jetta, and the heat exchanger was taken from a gasoline-powered VW van. Cal moved the battery about eight or ten inches to the right to make room for the compressor. He had to weld up a custom mount for it, which is visible in the photos. The heat exchanger is in a compartment above the back seat. An on/off switch is installed on the dash for the driver's use.

Overall, I am very pleased with this air-conditioned, tubro diesel Vanagon. I have never seen another one like it, and it may be unique in the U.S. Volkswagen should consider offering this package on their Vanagons. I believe they would be good sellers."

Apparently, Volkswagen disagrees. Instead of expanding the number of models available with a turbocharged diesel, they've dropped the engine entirely and now offer just the naturally aspirated diesel.

And you can only get that in the Golf. In my travels, I've seen only two other factory turbo diesels on the road, one a Quantum and the other an '84 Jetta. I think I'll hold onto my '83 Jettaq with the factory-installed turbo; it may be a collector's item some day.

< picture captions >
"View of the engine compartment, showing compressor and relocated battery."

"Rear view, showing air inlet to the air conditioner heat exchanger. You have to be careful not to load up the storage shelf just in front of the air inlet and thus block the air flow."

"Interior view of the AC's cold-air outlets, situated in a storage compartment above the rear seat. This now contains the heat exchanger, fan, etc. The temperature control (normally set to maximum cool) is to the left of the air outlets. The large round items on each side of the AC unit are radio speakers. The drain for condensed water from the heat exchanger is through flexible plastic tubing through the storage compartment on the right.

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Tom Carrington