On my race car (it's a NA, but has the turbo oil filter console and external cooler) I wanted to remove the oil thermostat and fix it so the cooler loop is always open - for maximum oil cooling.

I thought I'd share how I did it, in case if helps anyone else.

-First picture: you undo that large cap behind the oil filter if a 17mm allen socket (the same one as the tranny drain plugs). In side is a spring, the steel "valve" - which is a sort of plunger thing - and the thermostat. Similar to the coolant thermostat, the system is designed that when one "loop" is open the other loop is closed. In the case of the oil system, Chris White helped me figure out that the oil come from the block, goes into the middle of this oil thermostat area, than flows threw the "windows" directly to the oil filter when the plunger/valve is down, or, once the thermostat warms up, the plunger/valve moves up, and the oil flows through the windows to the oil cooler, back from the oil cooler and to the filter.

I ended up making a little aluminum cylinder with a step to hold the the windows in the position for just the oil cooler.

-Second picture: my aluminum cylinder in the plunger/valve (you can see the windows here), and the stock oil thermostat.

-Third picture: in case anyone else wants to make one, the bottom face of the cylinder should be 35mm from the bottom of the window.

-Fourth picture: now, when my plunger/valve is in place, looking through the oil cooler fitting with a bore scope shows the window is in the center of the passageway - allowing full oil flow to the cooler.

 

Pretty slick.

Do you have any concerns about getting your oil up to temp before you hit the track on a cool/cold morning, or are you thinking that warm-up laps will be enough to get things where they should be?

I ask because I've been warned before by Dave Lindsey to wait until the oil is up to temp (140°F anyway) before going to full boost to preserve the turbo bearing life. On my street car, my oil rarely even exceeds 140°F during normal driving and it takes at least 10-15 minutes to reach that point on cold mornings with a new oil T-stat in place.

 

Good question... and I suppose I'll find out soon enough. My plan is to just let it come up to temp before pushing hard. (And my car's an NA.)

For what it's worth, I was on-track in november - there was ice on the car in the morning - and was seeing 240 degree oil temps half way into a 20 minute.

 

Are you running a stock cooler? 140 is pretty cool. My car usually runs between 150 (idle) and 170 (driving) under regular driving.

What cooler are you running?

 

Were you thinking the oil therm was sticking closed or only partially opening? Depending on which therm version you had (old or new), the therm will be wide open between about 205-220F.

If the therm is working properly (fully open at designed temp), there will be no change to max oil temps by forcing it open, it will just increase how long it takes for the oil to warm up (which wont take long on track, but will take a long time when idling in the paddock on a cold morning). Oil temp rise above the thermostat rating can only be controlled/reduced by increasing cooling capacity. What am I missing?

 

You're not missing anything. I'm putting on a larger oil cooler. And, while I was at it, I figured that I'd make sure I had full oil flow and not have to ever worry about a failing thermostat.

 

Stock oil cooler, and the 140 temp is in the pan measured with a sensor drilled into the oil drain plug.

I've also got a low-temp coolant thermostat (180), so that is probably helping to keep my oil cool too. The only time I see warmer oil temps is if I've been driving for a while then stop at a few lights... the oil temp will go up to 180-190. I haven't had the car on the track for more than 8-10 laps (short TT sessions) yet, so I don't know what my oil pan temps will be for an extended track session.

 

Good point. I saw that, but I've always got turbos on the brain! Disregard.

 

I very seldom ever heard of a failure with the oil thermostat staying shut, unless I'm just not tuned in with that.
If you're running a larger cooler, I would think it would be even more of a reason to have a working thermostat in place.

At what oil temperature does the stock system let oil through the cooler?

Slightly OT, but I also remember finding out at one time that once the set temperature has been reached, and the oil starts flowing through the cooler, the oil temperature has to drop quite a bit below that "set temperature" in order for the thermostat to close again. Unlike the coolant thermostat, where it is constantly moving between closed and open to modulate the temperature.
Is this true?

 

Déjà vu... post 19
https://rennlist.com/forums/944-turb...hermostat.html

 

The thermostat I took out was 105C.

 

So, here's my new oil cooler. Hopefully I'll have happy engine oil.

 

Did you use AN12 size lines/fittings?

 

Yep. -12AN.

 

I will do this to my spec 944 my Oil pressure starts to drop after about 10 mins on track and the only thing that could be causeing it is high oil temp.