diffusers

[JONKATHY]

I can't find in the SCCA rule book the rules relating to diffusers on fc cars.
The drawing on page fcs 30 seems to be missing some dimensions.
Can someone help?
Thank you, Jon

[Mike B]

Under section C (in my 2000 GCR) it states:
"Deviation of the undertray may not exceed 2.54cm (1") in the area between the rearmost point of the front tire to the frontmost point of the rear tire. Diffuser undertrays are permitted."

Hope that helps!

[JONKATHY]

WHAT I REALLY WOULD LIKE TO KNOW IS WHAT THE SIZE LIMITS ARE IN PLAN VIEW.
THANKS FOR THE REPLY.

[Mike B]

The way we interpret the rule is that it is the maximum body width behind front wheels, dimension J in the GCR, which is 95cm or 37.4" (we round down to 37-3/8".) This makes an almost seamless transition between the sidepod/floor and the diffuser, at least on the newer Van Diemens. It also lines up with the width of the wing.

There really isn't an explicit definition of the diffuser width in the book, so we go by that rule. If I saw one wider, I feel it would be protestable. Besides, if you go much wider, you get very close to the rear tires and all the turbulent wake they cause.

[JONKATHY]

THAT IS WHAT I NEEDED TO KNOW.
THANK YOU MIKE.
JON STAUDACHER