Jaco Swanepoel wrote: >> I came across a link of a guy in South Africa that built a high >> performance engine for drag strip purposes out of a VW type 4. I know we >> dont get close to those kinds of rpm, but I was wandering if the valve >> setup might be a good idea. "Use Nissan valves (big and cheap), 2.8 Skyline inlet and 2.4 Tracker exhaust. This does wonders for the breathing. Use 2L hydraulic valve springs, they can take the punch. "<<
I doubt it. I don't know the exact sizes of the valves that are mentioned, but I'd think that at the kinds of RPMs that airplane guys are running (maybe 3400 rpm direct drive), there would be little if any gain to be had. There may even be disadvantages. For instance, slapping a big-valve 140hp head on a 110 engine does no good at all from a power standpoint, but adds the DISadvantage of more likely seat failure due to inadequate material between the valve seats. I would think VW sized their stock valves for exactly the RPM range that we are flying in, so personally, I wouldn't disturb the stockers, other than replacing them with Manley or some other high quality stock sized stainless valves. On the other hand, Type 4s are more prone to seat failure than the Type 1, so upgrading one valve size would make sense if the seats show any sign of looseness or need replacement due to wear anyway, but I wouldn't put any huge valves in there hoping for a power increase. There are some more details at http://home.hiwaay.net/~langford/kvw.html , but you've probably already seen it... Mark Langford, Harvest, AL see homebuilt airplane at http://www.N56ML.com email to N56ML "at" hiwaay.net
