The Type 4 engine comes stock as a minimum of 1700cc when the Type I engine comes stock with a maximum of 1600cc. It is only natural that the Type IV engine would end up in place of some Type I engines.
The type IV has evolved from the Type I. The errors made when creating the Type I engine where solved when the Type 4 was developed.
There is a sort of rivalry between the Type I fans and the Type IV fans. The Type I engine is the most common engine found on air-cooled world and therefore has many fans. The type IV is less often found as it was many used in VW Type IVs, 1972 and after Type II and Porsche 914. It has a bad reputation because the Type IV and the Type I, though both air-cooled engines are tuned differently. Yet both engines have advantages and disadvantages depending on the application they are used in.
There are several experts on the Type IV engine and it's conversion:
- Joe Cali is the author of the first guide to the conversion: The Type IV Upright Conversion Manual. This guide is a must have for anyone considering the conversion. It is a DIY guide in Black and White which explains everything about the conversion. This website is nextgen-usa.com.
- Jake Raby is the person who knows everything about the Type IV engine in and out. He not only sells all you need to do the conversion. His contribution to the Type IV engine is enormous, in part thanks to the time and energy he spends in research and development on this engine. The is also the person who took over the DTM (Down The Middle) cooling system. This website is aircooledtechnolgy.com.
Type IV VW Conversion Webring: