Hey
Its is extremely important that you allow the turbo a "cool down" period after any journey.
Correct
Turbo's can spin up to 80 000RPM (If not more) when they are in use.
You missed a leading one. An average turbo speed on big truck turbos is around 160,000 rpms. On smaller car sized turbos, particularly the K03, they can run upto 240,000 rpm!
Now most turbo's share oil from the engine and are only lubricated whilst the engine is running... The constant flow of cooled oil whilst in use is what lubricates and keeps the turbo cool.
Spot on :afro:
This is where we have an issue.
When you switch the GTI off (or any other car for that matter) the oil flow stops and your turbo goes into a phase called Heatsink.
This is where most of the damage is done. Shortly after turning the car off the turbo can reach temperatures of up to 200 degrees celsius. Because there is no flow of oil this means that the oil still in the turbo also reaches those temperatures. This can (Depending on the spec of the oil in your car) lead to graphite formation and the oil solidifying inside the turbo... (I think its graphite formation - Cant remember)
Actually, you have the fundamentals correct, but most turbos can get upto around 350 to 450 degC.
And the oil turns to solid carbon, not to dis-similar to coal - which took the earth millions of years to form!
The next morning when you switch your car on the turbo breaks the solidified oil and imagine if you will; a rock scraping against Greenouses paint... Thats the effect you get.
Owch - that analogy sounds painfull - especially to Nathan!
But again, yes, fundamentally correct. The hardened solidified 'chunks' will slowly wear away your bearing shells - which will then cause a lowering of oil pressure - not good!
So ideally about a mile from home you should ease of the accelerator, use less boost by keeping the RPM down and allow the turbo time to cool down.. That way when you switch off the effects of heatsoak are not as bad.
Spot on again. Ideally, what you need to be doing is staying in 6th gear, with the least possible revs and throttle, but with a fairly decent roadspeed - so that there is a good airflow through the engine compartment, and the radiators.
Im sure TT will be through to tear apart my explanation but that is as I have been taught in the oil industry how to deal with turbo's.
No tearing apart needed