The stock parts
The flywheels used on Type 4 engines can be classified into two different categories: VW and Porsche. The Porsche 914/912E used a different flywheel than the VW cars (411, 412, and Bus). The Volkswagens used four different flywheels, each having a different diameter clutch disc and pressure plate. The very early 411 used a 200mm clutch, thus it is compatible with the popular aftermarket Type 1 clutch discs and pressure plates. Next came the 210 mm, 215 mm, and the 228 mm flywheels.
The 914/912E flywheel had a 215 mm diameter face and used a unique pressure plate and disc to mate it to the Porsche transaxle. This flywheel differs from the VW flywheel in that the starter ring gear is offset differently and will cause a VW starter not to engage properly. This flywheel will be necessary only if the car you will be installing the Type 4 into uses a Porsche transaxle, such as the 901 or 915. The rest of this tech article will cover using a Type 4 engine with a Type 1 transaxle, as you can use the stock Porsche starter to finish the Porsche setup.
The Type 4 200mm flywheel was only available on the 1969 VW 411. This car was only available in Europe in limited numbers, so finding this flywheel is quite difficult. Due to this scarcity of the 200mm flywheel, Kennedy Engineering, the makers of the famed KEP pressure plates and adaptors, offers a 200mm flywheel for the Type 4s. By using this flywheel, or the original 200mm, a Type 4 engine will slide right into a standard 12V Type 1-3 transmission. These flywheels also give the engine builder a large variety of proven pressure plates and clutch discs. A standard 12-volt Type 1 starter meshes up perfectly, with the self-supporting Bosch SR17X being my favorite.
The Type 4 200mm, the 210mm, and the 215mm are all the same outside diameter and are basically identical with the exception of the clutch face diameter. The starter ring tooth count is the same as a 12V/200mm Type 1 (130 teeth). The 228mm flywheel has the same starter ring, but the raised portion on the outer edge of the flywheel makes it larger overall and requires the use of a self supporting starter.
As the diameter of the pressure plate increases, the issue of pressure plate height becomes an issue. The larger pressure plates are more likely to have clearance issues in the bellhousing where the housing slopes from the input shaft to the outer lip. It is here that you will run into problems with the 228mm flywheel. It is possible to clearance safely for the 215mm, but the 228mm leaves the bellhousing quite thin.
Now let's take a look at the issues of flywheel selections and the best options.