Like the above says.
Other than the carbon graphite wear surface on these housings, and the spark plug water cooling chambers,
what other differences are there?

 

Intake port is bigger on the FD. Check out that RE video floating around. They show shots of a FC, FD, and 20B housing.

 

anyone got a link to this?

 

hmm, there are no "intake ports" on "rotor housings" but nice try the "exhaust ports" are bigger though

 

Maybe some of us have a PP motor....
But yeah, I was aware of the bigger intake ports in the REW front, intermediate, and rear housing, and the various other signifcant diffs, like the dowel pin area.
I was just curious to see the video.
Sean Cathcart