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Re: Turbo autoshutoff? Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 19 Jul 2005 05:38:11
In Reply to: Turbo autoshutoff?, frefoo, Mon, 18 Jul 2005 20:15:51 Members do not see ads below this line. - Help Keep This Site Online - Signup |
As REM says, not really necessary.
The turbo has a water jacket, and that helps limit the thermal rise after you shut the car off. The water jacket and oil flow pull heat away quickly. The turbo gets very hot at high boost/rpm, but cools down quickly as the engine revs and boost drop. And the turbo impellor also spins down quickly.
What you don't want is an impellor spinning at 100,000 rpm suddenly losing oil pressure when the engine is shut down. But it doesn't usually spin that fast.
If you've been running at full boost for a bit, pumping lots of heat into the turbo, and at near full-bore and 5000 rpm, power-slide the car into a parking space and shut it down, yes, that would be bad for the turbo. It would also be bad for your license and insurance rates. The turbo would be hot and the impellor spinning fast.
However, if you've pulled off the highway after a high-speed run, and you're running the car at reasonable RPMs (2-3K) and minimal boost, by the time you get off the ramp, down a few side roads, and into your driveway/parking lot, the turbo would have cooled down and the impellor is not going very fast. You can shut the car right off. Sane and reasonable driving at 2-3K rpm cools the turbo down almost as much as idling.
I've been running Saab turbos since 1986 with no turbo-related problems. And that '86 was the non-water jacketed turbo. If I pounded on the car, I'd make sure I took it reasonable for a few minutes before I parked it. If I'd been driving reasonably, I just shut it down.
What is more important is start-up. I let the car idle for 30 seconds or so before taking off. More if the engine is cold, less if it's warm. I don't stomp on the throttle before the temp needle gets up off the peg. That's true of any engine, turbo or not. Wait for the oil to get warm and flowing, and give it a chance to reach all the bits.
posted by 192.249....
, Tue, 19 Jul 2005 05:38:11 <-- Viewing This Message
, Mon, 18 Jul 2005 20:38:32
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