idrive

I know I could research this but...

My kid lets his Subaru idle for a few minutes before he turns it off. He says he is cooling the turbo down. He says I should do the same thing because of the super charger. ???? What's best for a supercharged engine before shutting it down, let it idle for a few minutes or shut her right down??

vraa

You don't have to do that for your supercharger because it spins off the belt, turbos spin off the exhaust gases.

I can't remember why they do that for turbos though.

Kanji

yes, turbo spins on the hot exhaust and the cool air from the inter-cooler, plus turbo's has a thin oil that lubricates the bearing that spins the fins. cooling the turbo after a hard drive is a good idea using a turbo timer, so you don't have to sit in the car and let it idle. Super charger is another thing, since its not using hot exhaust to spin the fins, and it spins by belt driven...i don't think you have to let the turbo cool off, but would let your engine cool down. like drive easy for the next couple miles till you get to your destination if that helps.
Turbo get its lubrication by pumping oil in the bearings. if the engine is shut off before cool down, there's no oil being pump in to help transfer the heat away..so the turbo cooks while trying to cool off, without the oil to help the heat disipate.

ToboC32

In addition, thanks to the clutch the supercharger isn't spinning at idle anyway.