Techno Duck

If you dont know the history, i recommend checking the condition of the smaller turbo thermostat. I have seen on two occasions it being seized closed, one being on my car. I ended up leaving it out totally and now just give it a few extra minutes before getting on boost.

With that said i agree that water cooled will probably further increase turbo life. Even with the functioning turbo waterpump, I also let the car idle for about 10 minutes after coming off the track just to let the cooling system play catchup a little. I also leave the hood popped so heat soak isnt too bad and the turbo waterpump wont constantly cycle on and off.. on one occasion the pump stayed on for like 10-15 minutes after coming off the track on a really hot summer day at NJMP, i was scared it would kill my (lightweight) battery! What i really like to do is drive around the paddock a little before parking the car to keep air flowing over everything.

mtnman82

Does Clark's talk about the smaller turbo thermostat? Is it located in/near the water pump?

Techno Duck

To access it you need to take off the plastic front fitting on the waterpump.

mtnman82

Thanks - I think I remember putting this in when I resealed the front end (years ago now).

So if this small thermostat fails, after shutting down water gets sent to the (possibly very hot) turbo?

Can you guys recommend a good diagram of the cooling system?

Edit: found one on Clark's

hp18racer

I had a turbo cooling pump crack on the track. Lost coolant and overheated, blew the head gasket. How many more failure points does the water cooling add? Count the hoses and connections. My street and track cars are both oil only.

Droops83

My '86 has 146K miles now, original turbo, engine has never been apart. It is my daily driver and at least 10K of those miles are track miles. I like the water-cooled turbo/auxiliary coolant pump for the street driving, as one does not always have to opportunity to idle for several minutes after every single drive. This is definitely conducive to the life of the turbocharger. I have always heard of the notion of eliminating the water cooling for track cars as the coolant gets superheated by the turbo. I would not disagree with this notion. I used to have the coolant temps climb on 90 degree+ track days about 5 mins into the session, but I added a second stock oil cooler inline with the original and that has been cured. Lower oil temps beget lower coolant temps, especially with water cooled turbos. I am running stock boost levels, however.

No matter how the turbo is cooled, the engine should be idled for several minutes after a track session, not only to circulate oil through the turbo, but to circulate coolant through the engine. Even an NA 944 can have the coolant boil over if the engine is shut off immediately after pulling into the paddock.