The gentleman I bought the engine from puposely bought it with a 2" prop hub extension. He said that he had intended to make more room for the air to enter the cowling, so it didn't just ram into the front cylinder and spill out, or slow down.
I've heard from several people that the 3300 Jabiru engines are hard to keep cool in the Sonex cowling. So, given this info, and the fact that I already have the prop hub extension, I decided to go ahead and do the modification.
A friend of mine gave me the standard length hub, so I can revert to that if this doesn't turn out, or if I hear that this is a terrible idea for some reason.
