This page was last updated Friday, May 18, 2007

The obvious conversion is adapting the Type 1 alternator (or generator) to the Type 4. It's an obvious choice because the alternator, fan, pulley and hardware are easily obtainable and reasonably priced. Most VW nuts probably have these parts laying around in the garage or in storage.

These conversions also make the engine look more like a Type 1, introducing a stealth-like appeal to the engine. Only upon closer inspection does the average VW gearhead realize that your engine isn't a Type 1. Some of these conversions appeal to own a vintage car; they don't like the monster fan staring at them when they open the decklid. Others, like the DTM and the one piece shroud, give the engine a unique look.

Before you read this tech article, I would highly recommend you read the tech article on upright conversions, specifically my paragraph about internal/external oil coolers. I feel this is an important issue to be familiar with before you decide on which conversion is perfect for your car.

Let's now look at what conversions are available that utilize the stock Type 1 alternator.

Stock Type 1 fanshroud

This conversion was engineered by Joe Cali of Next Generation. Joe explains how to use the stock Type 1 and Type 4 sheetmetal and how to combine them together to make a conversion. The plus side of this conversion is the minimal cost, and use of the stock thermostat. The minus side is the labor intensive nature to assembling the conversion as not everyone has access to shears, welder, etc. that are required to assemble this conversion. If you are good at fabricating, this conversion should be top on your list. You must also have access to a large quantity of stock Type 1 and Type 4 engine sealing tin. Buying the needed tins can be expensive if purchased seperately.

There is another conversion that uses Type 1 hardware. Sharpbuilt of Australia manufactures a pair of fiberglass head tin that allows the use of a Type 1 fanshroud on a Type 4. These would make an upright conversion easy to assemble with an aftermarket 36hp style fanshroud, crankshaft pulley, and a conversion alternator/generator stand. The rest of the engine tin is also available from Sharpbuilt in a package. This tin is not needed if this engine is be used in a Baja bug or dunebuggy.

I've never used either one of these conversions, but if you have a stock, or near stock engine, this conversion may be for you. I encourage you to continue to read this article, as the DTM shroud solves some design issues that are present with using the Type 1 shroud.

Fiberglass fanshroud

If you are looking for something more than what we covered above, then this is what you want. These shrouds are specifically designed for the Type 4 engine and it's unique needs.

DTM: The late Joe Locicero of Oregon Performance Products is the creator of a great conversion called the DTM Upright Shroud. With Joe's passing away in July 2002, Raby's Aircooled Technology has acquired the tooling for the DTM and taken over production of the DTM. They have taken careful consideration to make sure that the quality of the new shrouds meets or exceeds those made by Joe himself.

The DTM shroud features many design points that make it probably the most effective upright shroud on the market for the Type 4. Let's glance at what makes it the performer; more information can be found at massivetype4.com.

If you look at a DTM from the bottom, you'll notice that the shroud curves as it meets the #3/#4 head. This offset, which is unavoidable for a horizontally opposed engine (flat), along with the directional vanes seen in this pictures have been dyno tested to deliver the cooling air to the hot spot of the engine.

The cooling that normally would hit the top of the shroud and generally go no where has been addressed with this shroud. Joe cleverly ducted the air from this point and routed to a compartement on the back of the shroud. Inside this compartment is the stock oil cooler, relocated. This way, even at idle, the oil cooler is receiving a constant flow of cooling air.

Raby's Aircooled Technology has extensively dyno tested and road tested this conversion, along with many other conversions, and they've found that the DTM provided the coolest operating temperatures, and the most even temperatures from one cylinder to the next.

I've received a lot of favorable feedback from people who've purchased this shroud. The quality is superb and it's been effective in cooling Type 4s over 2600cc. This is the best deal when it comes to upright conversion, in my opinion.

Others: A few other manufacturers offer fiberglass shroud conversions, including FAT Performance, German Auto-SACO, and a few other companies whose names I can't recall at this moment. These shrouds generally locate the alternator over the middle of the engine, and incorporate the head tin into the fanshroud, as does the DTM shroud.

Although these shrouds are inexpensive, they are not a smart purchase. Generally these shrouds lack the performance and features of the DTM shroud.

My first point is the placement of the fan in the center of the shroud. This does not, I repeat, does not help with the cooling performance of this shroud. Due to the design of the Type 1 fan, the air coming from the fan is traveling in a radial path. This path is a natural straight shot to the #1 and #2 cylinders and head, but the air meant to cool #3 and #4 just hit the shroud and increase the air pressure on that side.

Another problem is how the shroud covers the cylinders. Generally these shrouds allow an open shot to the #1/#2 cylinders and head, but because of the increase offset of the Type 4 engine, the cooling air on the #3/#4 only reaches one cylinder and only one side of the cylinder head.

These conversions also require that the oil cooler be relocated and they generally do not come with provisions for sheetmetal to seal the engine in a fully enclosed engine bay. These engine conversions were created for the off road crowd, like the desert racers and the sand crowd. They are simple and inexpensive compared to DTM's kit, be careful, as you usually get what you pay for.

I've had reports from builders that these conversions lack directional vanes in the shroud to help direct the cooling air to the hot spots of the engine. The quality of these conversions vary greatly, so it's buyer beware. Make sure that the company you buy from is willing to stand behind what they sell.

The bottom line

If you couldn't tell, my favorite conversion with the Type 1 alternator is the Raby's Aircooled Technology's DTM conversion. It's a well engineered kit, and is very complete. The company stands behind what they sell and they only sell what they use on their own engines. The optional cooling tin make it perfect for the street Type 4, whether mild or wild.

If you can't afford this conversion and your needs are modest, I'd consider either The Next Generation conversion or a pair of the fiberglass head tin from Sharpbuilt. Both are economical for converting a stock Type 4 to upright cooling.

Thanks to Rolf Christensen and Jake Raby for their sharing of information. Thanks guys!