From the home of Porsche, there are different transmission types, which are more or less well suitable for installing into the Volkswagen Bug. Basic precondition for the mounting is that the transmission fits into the Bug at all somehow. Somehow doesn't necessarily mean, however, that one must perform serious cuts at the floorpan.
The 901 and 914 series are the best transmissions that fit into the Bug. These transmissions have casings that are only marginally bigger than the original Bug transmissions. The 901 transmissions were in the 911 Porsche models until 1972. The 914 transmissions, quite clearly, were installed in the "Volksporsche-models". There were two basically different types. The 1.7 models had the shift mechanism at the nose cone, whilst the 2.0 transmissions had it at the main housing on the side.
The gear ratios of the old 901 transmissions differ only little from those of the 03S-transmissions. Their gear ratios are not suitable for the big, torque-strong type-4 motors although they stand the same torques as the 914-gearboxes. They are well combinable with high revving small engines upto approximately 2.000 cm³. The transmission of the series 914 runs in the wrong direction in the Bug, since originally constructed and built for a mid engine car. Here the direction of rotation must be altered by flipping the differential. These transmissions have gear ratios that suit the engine displacement of huge type-4 engines well. We recommend them in combination with motors between 2.000 and 2.900 cm³. Power up to 240 HPS and torque of up to 270 Nm don’t represent any problem with these transmissions. Depending on wheels and engine, speed of more than 220 km/h are possible.
Transmissions of the type 915 were put into action in the 911 models from 1972 until 1986. These transmissions essentially tolerate more torque than the forerunners 901 and 914. 340 Nm are no problem for these gearboxes. Therefore they are also combinable with miscellaneous turbo engines, here only the Subaru Turbo 2.0 is mentioned, which easily reaches 280 HPS and 330 - 340 Nm in the open version. Disadvantages of these transmissions are their big housing and their high price as used part. They have a much longer main housing than the 901/914 models and are heavier than the forerunners, approximately by 10 - 12 kg. After all these already weigh 43 kg. Advantages are the essentially longer gear ratios already in the small gears and the easier shiftablity of the gears 1 - 4 being in the H-Scheme. Speeds of up to 250 km/h are no problem with the 915.