I'm thinking of going full width to the edge of the car by doing it in 3 pieces, plus small end plates. Has anyone tried this?

 

I've got the same idea, slightly different approach in that I'm going to make extensions for a 3-piece duckbill spoiler.

I've only made it as far as making templates.

 

Not 3 piece, but have seen this done on CSP builds

 

Yeah, that's what I have in mind, except the first section would turn the negative slope of the trunk, sides and rear end to be flat, and then the extension would be adjustable. I was also thinking little tabs that could connect the side extension pieces to the trunk extension piece for track mode.

 

I like that, thanks

 

Full width (or nearly) will be the most effective for making downforce at the obvious expense of complexity since it needs to be either multi-piece or detachable on the sides to allow the trunk to open. I would recommend against endplates as they'll worsen the L : D ratio for an already drag-heavy approach to making downforce.

 

I'd be interested in seeing how this works out. I've got the same duckbill (but only have the center section installed - because of laziness), and I'd like to see if there is any advantage to extending it.

 

Sliding/adjustable extensions is the approach that the NASCAR Xfinity cars have been running for quite some time now.

 

CSP Miatas is the way to go for inspiration on this. This is on our car. It's a blown up crop of the original so sorry for the quality. Angle aluminum (90*) was cut and shaped to the rearmost part of the trunk lid and riveted on. Ended at about 75* AOA. Then riv nuts inserted to the angled aluminum which serves as a bracket for the spoiler foil. We have another trunk lid getting painted that has had a stainless flat piece welded to it replacing the aluminum bracket. Should make for a cleaner look.

Spoiler is .060" aluminum sheet. Once it takes the shape/contour of the trunk it is fairly stiff. SP rules say spoiler should be at rearmost part of trunk but no part of the spoiler may go past the original bodywork as viewed from above and may extend a max of 10" from bodywork. So the spoiler ends at the sides as far as it can go without breaking the rules.

Struts secure the spoiler at the high ends where we thought it would do the most good. The struts were made adjustable at first but have since been replaced with aluminum stock and quick remove pins. The ends of the spoiler where it meets the bodywork on the sides has an angle bracket and the body has a riv nut. A butterfly fastener makes for quick disassembly.

All of this comes off for street driving or towing of course.

For more inspiration, google the "got cone?" pictures of the solo nationals and check out the csp cars. Lots of good pics of our homemade aero.

 

Is there much to be gained from the spoiler extending all the way to the side of the car past the edge of the trunk, like a BBFW spoiler? Just debating if I should buy the BBFW spoiler and be done, or build my own because I already have a sheet of lexan sitting around. My NB is used for autocross (not nationally competitively), some HPDE, and driven on nice weather days.