I'm looking to build a new diffuser on my car for next season and would appreciate any assistance from the clever people here! I've sketched the space I have available in Google Sketchup, which is bounded by the chassis, tyres and wishbones. I can extend beyond the rear wheels for 1500mm, according to the rules, but my trailer isn't big enough, so I've limited the length to 1050mm.
The static ride height is 60mm, but I don't have the tools to measure ride height on the track. Apex speeds vary from ~25mph at the slowest corners on the slowest tracks to ~80mph. Average apex speeds are ~60mph. Top speed is under 130mph. There's also the potential to reduce the height of the rear wing to interact with the diffuser more effectively.
Here's a side view of the car as it stands today.
The area shows the space around the chassis/wheels that's available. The floor ahead is flat (aside from rivets) and 1680mm wide. The small plate above the plan area shows the maximum height at this point, thanks to the wishbones. Both views are from the left rear of the car.
I've cribbed a basic diffuser setup within those boundaries and I'd be interested in your thoughts. The first section of the outer diffuser is ~4.2 degrees ramp angle, but widens at the same time, increasing expansion ratio. The second section of the outer diffuser and the central section are ~10 degrees ramp angle.