Car appreciation... the aesthetics, the engineering, etc

Could you share some info about how the drive train is setup on your cars?

Sure, it's pretty straightforward. The engines are rotated by 90 degrees compared to how they'd be in the bike, so they're longditudinal with the exhaust sticking out on the LHS. This is the R1 lump in my racer in place:

You then replace the cog on the output shaft of the bike gearbox with an adaptor flange which you can bolt a propshaft to, shown in the picture below. It has a large gear fitted to it as part of the electric reverse system - bike engines don't have reverse of course (except in a few very rare cases) and racecars have to have a reverse system.

The two are then connected by a custom-made propshaft. Because there's no gearbox running down the transmission tunnel as there would be on a conventional car engine/box combo the propshaft is long, and so includes a centre bearing to help ensure it doesn't flail around too much.

That's it, basically.