Turbochargers would work based off engine RPM and fuel consumption at said RPM (to simulate exhaust-driven turbines). Superchargers would work based off engine RPM and a gear ratio set in the JSON (belt-driven screws). Both would boost torque (and maybe horsepower a bit), but also cause the engine to over-rev easier and to accumulate hours faster, and maybe to use fuel a bit faster. They would have a max boost pressure also set in the JSON to prevent runaway, and turbos would have the number of them set in the JSON as well (maybe). Could be difficult, but worth it in my opinion. Let me know what you think.

You mean slapping a giant turbo on your engine and then blowing it up isn't arcade-y? Anyway, I fail to see how it would require a new part system. Just a few engine JSON variables. As to the tweaking, I'm the master of tweaking things until they work right.

While I see a use for this, #67 with Nitro is my preferred solution to getting more power out of engines. Turbo/Super chargers would require a new part system and would have to be tweaked significantly to get them to work right. Nitro is simpler to implement and is a hair more arcade-y which I feel will work better with more people's ideas of how the cars should control.