BBFW Lexan spoiler aero balance: How much splitter?
 

Getting ready to install a BlackBird Fabworx lexan spoiler, on my NA track car. I'm running a TT class that has no aero restrictions. Currently at ~15.5 lb/hp on 225 Toyo RRs.

Front will be an S1/S2 style poly airdam with birch ply splitter. I'm trying to determine how much splitter the lexan spoiler will be able to balance without being a parachute... Keep it flush (S2 rules)? 1-2"?

I'd prefer to be a little conservative than have to cut the splitter twice, but hoping someone can help out with a good starting point?

One thing you could try is to build a flush under tray (like S2 cars). Then make a few splitter "extensions" of various (or one with variable length) to determine what works best for your setup.

I can't give you an exact answer for what gives a perfect balance, but I can confirm that the 4" splitter I had on my NB was too big to aero balance out properly when I had my BBFW lexan wing. I upgraded to the NLR setup and my oversteer issues went away.

I'd stay at around a 2" splitter and see how that goes. You can always trim it down.

Thanks! I figured someone here would have some experience with this setup.

I also spoke with Moti yesterday, and he confirmed that 2-3" was probably the max. I'm going to start with 2" and evaluate from there.

I would work the other way. Start with 3 and bring an electric saw to the track, you can easily trim it down trackside.

I also have the BB Lexan which is not yet mounted. I have not built the front splitter yet and was hoping to lean on your trials. Please report back.

Not a bad idea. And an excuse to buy a battery powered saw... :p

Moti did suggest not trying to max things out to avoid an extreme angle on the spoiler. With only n/a power, I'm trying to keep the drag down. If I were doing AutoX, it would be a little different.

We run a 3" splitter, found the lexan with a 35° AOA worked best for us after racing at ORP with all its horrible off camber corners. Our chord length is a couple inches short of the S2 max length as well (not on purpose though)

With no aero restrictions in your TT class why not go with a real wing?