Quote:
Originally Posted by e46e92love
My1st has finally made a great point. See A418 what you fail to factor into your line of thinking is that the turbos are spooling down with no oil pressure, and even mild boost can induce 100,000 rpms from our little guys. Spooling down with no oil pressure can lead to earlier turbo bearing fairlure. Remember, they only warranty our cars to 50K, so for me (I own mine) I am doing the little things to make sure they make it 100k and maybe further
|
What you fail to factor in is that I have been playing with, and rebuilding turbos for years. I know more than you what kind of rpm the turbos turn and when they do it. I'm also here to tell you that unless you went full throttle and shut your car down, you AREN'T hearing your turbos "spooling down." The wastegating system on the N54 shunts ALL exhaust away from the turbine when the wastegate is open, which is all the time you don't have your foot decently into the gas. Even with this occuring there is still a bit of rpm in the turbo when you shut it down, but not nearly enough for you to hear anything. In a conventional turbo with a pressure actuated WG, it does not hurt the bearings with decreased oil pressure for the turbo decelerate to a stop once you shut down your engine (turbos spin at a fairly fast rate at idle as well, no amount of idling will slow them down any more.) ...And I own my car outright as well.
Cyruz, the S4 k03s are oil and water cooled exactly like the mitsus on the 335 are. The problem with the K03 was the amount of heat they and their support oiling and coolant lines were subjected to, as well as the insane shaft speeds needed for those absolutely tiny compressors to make any amount of appreciable boost.