A common upgrade to aircooled VW engines is the change from a non-doghouse (or "upright") fan shroud to a doghouse fan shroud. I'll explain why. Prior to 1971, the oil cooler in an aircooled VW engine was positioned near the #3 cylinder and was housed fully inside the fan shroud. During engine operation, hot air expelled from the oil cooler was released over the #3 cylinder, making it susceptible to overheating and related failures. VW corrected this in 1971 by redesigning