drsimon

Heat is one of the factors responsible for the deterioration of engine parts especially those made of rubber like belts and hoses. I'd like to share a piece of advice, which sounds very reasonable to me, given by my mechanic. He once advised me to raise the engine hood to increase the rate of cooling when the engine is switched off on reaching home from a drive. I know it makes sense because I always get a blast of hot air in my face when I do it! Imagine this hot air circulating under the closed hood in the notoriously cramped engine bay of the 951 when the fan is still blowing after the engine is turned off. Even when the fan finally stops, hot air rises, as we all know from elementary physics.
Except that when the hood is closed, there is nowhere for it to rise. So it hangs around longer than what is good for engine parts, delaying cooling. I have no direct evidence, nor read of any, that raising the hood on reaching home indeed increases the lifespan of my 951S engine parts. But the advice certainly makes sense, especially if you live in a hot tropical climate like I do.

Miles

What you say makes good sense, after all if you've ever been to an autocross check out how many hoods (or tails) are up between runs.

Danno

The only problem I see is that you have to raise the hood every time you stop the car. Even at stoplights in traffic because the heat does build up with fans running. Then every stop you make on your shopping trip you need to raise your hood as well.

I think that may be more trouble than it's worth. And there are a lot of rubber and plastic parts that get brittle with age, regardless of the heat. That's due to the outgassing of solvents and oils in the rubber & plastics due to their vapor pressure. Eventually, the rubber/plastic dries out enough that the next application of force breaks them. Take for example, the visor clips, dash-panels, cassette-tray hinge, Nordica ski-boots and other plastics parts that eventually break without any assistance from heat whatsoever.