Why is it that the fan cooled sleds have way less power than the same sized liquid cooled sleds??

Its all about the cooling. *A liquid cooling system can cool a lot better then a fan system and thus can handle more heat. *

Lets use the 500 rotax for example. *They have a Fan and Liquid of this engine. *

The liquid will have tighter tolorences more compression, Maybe a advanced timing. *All this stuff builds up heat. *Heat that only a liquid cooling system can cool. *

The fan version doesnt have the higher compression and will create a lot less heat and the fan will be able to cool it. *

One advantage of the fan is that when you have a lower compression engine you normally see a lot more life out of them. *Look at the 380 fan. *These things run forever.