Originally posted by Eric:
<STRONG>I haven't done any testing to confirm this, but I doubt the lack of water cooling is what made that single equipped car run cooler at the racetrack than a comparable BPU car. My guess would be that the reduced restriction on the exhaust side is what helps. Somebody on the mkiv list (Lance I think) said that the stock turbos have a terrible pressure ratio, with pressure in the exhaust manifold being 3 times that of the intake manifold. With a single, and much better exhaust flow from a header and bigger exhaust housing, less heat gets retained in the head area, and there is less load on the cooling system. I'm pretty sure the heat removed from the turbo by water cooling isn't very significant compared to the load on the cooling system as a whole since the amount of coolant that flows through the turbo just isn't that much(look at the size of the hoses and pipes).</STRONG>