Guess the race part

mopar head said
Looks home made, I was thinking crankcase vent, but I doubt any track would allow any vent to atmosphere. I lose.

Yup, it’s home made. And several years later I fixed the one issue it has, but it allows the engine to do something that it can’t do without it.

And it does have one flaw. That and it’s a PITA to set up. But once it’s on, no one would even know it’s there.