It down't mean ST4...and I have no idea what the 7 is after AI (for American Iron, another NASA class). I'm guessing it is the 4th gen of his ST splitter. They race STU/ST1/TTU/TT1 and AI. He sells for Corvettes, Mustangs, BMWs, and Porsches. He hired an aerodynamicist to get further a head; the guy he chose made a bunch of YouTube videos but was just starting out. One video interviewed one of his PhD advisor, another Andrew Brilliant on his Infinity Wing front splitter.

To the best of my knowledge these blog pages are the only ones publicly available with CFDs of the splitters we are talking about. By poking around there are articles how Dodge added 12 diffusers to the Vipers final front splitter, but no numbers. Pictures also show diffusers in the Camaro ZL1 1LE splitter.

This stuff is hard to come by. On one F1 forum years ago someone posted CFDs of different rear diffusers, Some were convex, some concave, etc. The concave, different from most (all?) aftermarket which are convex, had the most downforce and least drag. Then a look at Wehrlein's car on its side at Monaco reveals a concave rear diffuser. A Ferrari on its side this spring at Sebring also showed a concave rear diffuser. Amazing stuff...but not enough detail to carry through.

The rules for TTU/TT1/TT2/TT3 basically allow WTAC unlimited class aero. 6" wider on either side. 12" in front. Rear wing above the car and to the rear. AI, ST4, and ST5 are more limited. It's apparently possible to get over 1000lb of downforce at 100mph with a moderate increase in drag. Enough front downforce that the wing alone is challenged for rear downforce.

But it depends on what the driver's goals, who makes the parts, what the budget is. A lot of cars are in TT4 and TT5 for budgetary reasons. Those rules don't let cars have $2000 front splitters with multiple diffusers. But they let the owner's have lots of fun.

 

This is the underside of their C6 Corvette splitter:

 

That's all fascinating stuff but we are only concerned with TT4 rules on aerodynamics in this thread. No rear diffusers are allowed in that class either (I just got rid of mine to be TT4 legal)

Rules allow 1 front and 1 rear piece of aero. Obviously my rear wing is my one piece of rear aero.

Nothing can be added to the top, bottom or sides of the front splitter. So this study is to figure out what flat shape, size and length is the most effective (with relative trade off) for the TT4 class.

 

I kind of like the idea of adding mounting points to the front splitter to add/remove diffusers. So we can remove it for TT4, but be able to add them on and screw around sometimes.

 

There may be more downforce to be gained by tightly sealing the radiator to the inlet and the other side of the radiator to hood vents. The cooling system can be both a major source of drag and front lift. Oddly, RHR sells a hood duct:

 

I took and interpreted these as defining the airfoil elements forward and outside of the splitter element itself. This would prohibit the use of a CR lip or canards but it doesnt seem to address recesses and tunneling under the car (FWIW the OEM undertrays have functional tunnels that can be accentuated by just slotting a perfectly flat splitter, thus making the 3D element part of the BTM body shape and NOT the splitter itself).

Spats are very much allowed in TT4/5 as long as they are completely vertical and fit within size restrictions.

It seems to me like the intent is to curtail these sort of high-buck splitter investments in favor of more accessible home depot mods, but the way the rules are written it encourages more creative interpretation and obfuscated spending.

 

This page may give you some ideas: https://www.motorsport.com/f1/news/t...-prix-1058328/

 

I ran this splitter for a season and cut over a second from my lap time when I replaced it with a 2' splitter. It seemed to be drag related because the car's balance didn't seem to change much.