Landracing Forum
Tech Information => EFI Questions => Topic started by: n49racer on August 07, 2016, 11:39:18 PM
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Hi All
This year I will be running turbos on my AA/BFRMR. I wondering about cooling down the turbos after a run. My thought is to try and keep the engine running for some minutes after the run but I not sure how long or if it's even required. I'm running non water cooled non ball bearing turbos. What do you guys with turbos do? Thanks
Ted
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The only cooling that sort of turbo gets is from the oil flow and just a little from the air flow at idle. The problem is to cool it down enough that the oil in the bearings does not get cooked to tar or charcoal after the turbo shuts down. You are on the right track a couple minutes of low load idle to get the heat out of the scroll so it does not burn the oil, but will have to defer on a specific time recommendation since all my turbos have been water cooled.
The turbo buick guys usually say 30 seconds to a minute or two depending on how hard they were flogging the car before shut down.
Saab used to recommend a minimum 30 second cool down at idle before shut down on the Saab 9000 turbo.
With modern synthetic oils which have higher temperature limits than conventional oils used years ago it probably is less important than it used to be if you are running a premium oil.
You might put an oil temp gauge down stream from the turbo if your configuration allows, but 30 seconds to 2 minutes sounds like a good place to start.
The high power turbo diesel guys might have a better recommendation but that is what I recall on the subject.
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Thanks HOTROD, I was also thinking of an accumulator that would store pressurized oil then flow oil through the bearings for a time if the engine shut down. So far the keep the engine running theory is winning.
ted
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I am planning on an accumulator if I can find a place to mount it.
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I'm with you Sparky. I would think a gallon would be required :-o I'd need a luggage rack. :-D :-P
ted
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Just change to a Roadster Pickup.
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I have run turbochargers at Bonneville and drag racing for over 20 years and we do NO cool down at the end of any run.
First on a street car this is way more important due to the number of start and stops. But with modern oil the build up is all but gone.
We have turbochargers that have made 15-20 passes at Bonneville and 20-30 at the ECTA along with 50 plus dyno pulls on zero build up on the turbochargers.
The build up is not going to be a problem with yours. The bigger issue you have is cooking everything within 10 inches of the turbo chargers when you stop. Running them only makes that worse.
make sure you shield everything near them!
Have fun and look for us on the salt.
Car 80
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Thanks for the info Paul. I was stressing over trying to keep the engine running for such a long time after a run but maybe if I can keep it running to the return road it will be fine. Stan, I just happen to have a roadster pickup sitting in the garage :-D :-D :cheers:
ted
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. . . it's all coming back to me. How could I forget!
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Yeah like Paul says, keep it running until you get it to the return road and just listen for it to come back to idle for ten seconds or so. Listening to how it idles is my first step in analyzing engine condition.
Rob Freyvogel
#496
AA/BFS