Re: Turbo cool down

Posted by RodInNS on March 23, 2006 at 15:04:37 from (142.177.102.2):

In Reply to: Re: Turbo cool down posted by NC Wayne on March 22, 2006 at 22:45:41:

As far as I'm concerned, whether you call it spool down time or cooling time doesn't really matter. If you let an engine idle at 800-1200 RPM you will get the benifit of considerable reduction in EGT, along with allowing the turbo to slow. Call it what you like. 2 minutes at 1250 RPM will cool much more than 2 minutes at 650, at no load. The fuel input between the 2 is negligible while the air movement is roughly twice at 1250. Naturally, twice the air movement will carry away a good deal more heat.
I'm sure there are turbo's that spin for minutes after shutdown too. However, the ones I deal with generally do not. I suppose if I pulled the intake I could tell you exactly. What I do know is that for the most part, they drop below the audable range withing a few seconds. One can assume that they don't spin for minutes when you can only hear them for a few seconds.
Beyond that, the EGT's I cited are certainly extreme examples. I haven't lost a turbo with those temperatures either. The one that was lost was on that engine, before it was turned. There was about 3000 hours service, and most starts were straight into use, and most shutdowns were park and pull the shutoff. The oil changes were all done well ahead of schedule, with the best oils available at the time. So there wasn't much else to blame it on other than misuse.
As I recall, your original statement was that EGT reduction played no bearing in the life of a turbo. However your own advice in allowing a turbo to spool down would easily allow the cooling that is necessary. I guess we could argue this all day.

Rod

Replies:

• Re: Turbo cool down NC Wayne 19:20:38 03/23/06 (1)
  • Re: Turbo cool down RodInNS 20:04:54 03/23/06 (0)

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