With the modern water-cooled turbocharger we've certainly reduced - but not completely removed - the need for turbo timing.

The advent of turbo timers was early in the piece with cars like Nissan Pulsar ETs, which used just an air-cooled or oil-cooled turbo. Nowadays the development has been to put a full 360-degree encasement of water around the core. So, really, all you've got now is one end that gets red hot if you've been charging along quite hard, and - hopefully - the other end is nice and cool if you've been picking up cool air.

A gasoline engine at an idle isn't going to drop an enormous amount of temperature. If you let it idle for 15 minutes it'll drop, but it'll still stay hot due to the combustion of the gasoline. Some people might want to let it idle for a short length of time - but if you've just been chugging around town or locally, you only need to idle into the car park and switch it off.


The other thing we want to do is make sure the turbo is spinning slowly before you shut it down. Many times I've seen people come into a car park quite quickly, turn the key off, pull the handbrake on and the turbo is still spinning down even when the engine's stopped rotating and there's no oil pressure. This continued spinning is particularly noticeable if you're in an off-road race vehicle and you have a spin and stall the engine. You can still hear the turbo - especially if it's a ball bearing unit - spinning some minute or so later.