Subaru Turbo Cool Down Procedure

Originally posted in 2011. Re-posting here for easier member searching.

 

 

It is not necessary to perform a “cool down/idling” procedure on Subaru WRX/STi/LGT/OBXT/Forester/Baja turbo models, as was recommended with past turbo models. The current 2.0/2.5 liter turbo engine has a far greater cooling capacity and, coupled with technology advances, makes this practice no longer necessary. This explains why information about a cool down is not included in the Owner’s Manuals. The heat contained in the turbocharger begins to vaporize the coolant at the turbocharger after the engine is stopped. This hot vapor then enters the coolant reservoir tank, which is the highest point of the coolant system. At the same time the vapor exits the turbocharger, coolant supplied from the right bank cylinder head flows into the turbo. This action reduces the turbocharger temperature. This process will continue until the vaporizing action in the turbocharger has stopped or cooled down.

So anyone with a turbo timer on a 2.5 has wasted their money.

If using a liquid cooled turbo, generally yes. It would take a custom set up with no reservoir and or real track time. If track time requires more cool down a turbo timer would not normally be the method used.

 

A turbo timer is for a daily driven oil cooled turbo car.

If I’m driving hard if I’m about a mile away from my destination I ease way up off the throttle