RajDatta

Just curious. I finally got the car running and after fixing a few oil leaks realize that when I shut the car off (its still on stands and I normally only idle it), I can hear the turbo spin for atleast 30-45 secs. Is this typical of any turbo or is it cause its a GT30 with dual ball bearings.
TIA.
Raj

Ahmet

Spool up? No, and yours doesn't either. Spin, yes. If it's making audible noise after shutting the car off, there may be something wrong with it.
Ahmet

RajDatta

Trust me, its just a spinning sound. It can't be anything wrong as the turbo is brand new.

westcoastprshe

Of course it will spin a little, there is some exhaust coming through to turn it. It won't make any pressure at all, of course. Spinning for 30-45 seconds after the car is shut off is pretty impressive though! Even with ball bearings, that's a long time for something to spin that has very very little weight to it.

Mike Murcia

Do you have a turbo water pump? They usually run for ~30 seconds after you shut the car off. It's not a spinning sound, and I don't even know if that turbo is water cooled, but it's just a thought.

BoostGuy951

I'd be pretty happy if my turbo spun for 30 seconds after shutoff. Thats like a .00000001 coefficient of friction.

Ahmet

A spinning sound? What do you hear, air being moved around? My K26 will spin for 5 maybe 6 seconds after shutdown from idle, with no audible noises.
Ahmet

gstreev

You must be referring to the Turbo Water Pump.

cpt_koolbeenz

And the difference is? I knew what you meant...

I have played with turbo's with engines running whilst the cold side of the turbo is not connected. Did that with my 924 BAE kit. Had the hot side plumbed, and the cold side open (with a filter). Also did it with my 951 without the charge piping attached. (MAP will let me do that) The turbo at idle is the best hairdryer I have ever felt! At 2k RPM it blows crazy hot air... You can feel it from about 5 feet away or more. It DOES spin at idle... but it doesn't sound like that is your problem... 30 seconds would be a VERY long time for the turbo to spin after shut off.

Sam Lin

With good ball bearing turbos, it's common for the turbo to stay spinning a long time after shutdown. Kinda makes you wonder why people even use sleeve bearings any more, the difference in lag is so obvious!

Sam

nick_968

A friend of mine from the Cosworth world of tuning where mega Garett ball bearing turbos are used said this is quite possible, and depends on your setup and how hard you have been working the turbo.

Ahmet

From idle?
Ahmet

Sam Lin

Yes, from idle, the turbos are spinning plenty quick at idle.

Sam

RajDatta

I don't have a waterpump for turbo cooling. I am running water cooling but its without the pump. They are direct runs from the coolant pipe.
The sound is definitely coming from the turbo and its atleast 30 secs from when I shut the car off. It takes approx that much time to just shut a car, get out and walk up to the front and then hear it for the next so many secs.
Just spoke to Chris Cervelli and he confirmed that its normal for the GT series ball bearing turbo's to do that and it threw him off the 1st time as well.
Not sure I would classify this as a problem .
Regards.
Raj

Mike Murcia

Hmmmm.... Sounds pretty messed up. Better take it off and give it to me. I'll even give you a K26 just because I feel sorry for you.