Oil Cooler choice revisited

[tmoretta]

I am in the process of rebuilding my 2.0 engine (with the help of Larry's in Groton, Ct.) I had decided on ditching the oil/water separator in favor of a side vent mounted cooler. But, Gary at Larry's says that he had one customer with a high horsepower subie that after doing the same, experienced very high coolant water temps. Only after replacing the external oil cooler with the original piece was he able to lower the temps. to normal. Could it be that the original "separator" is, in fact, an oil cooler and not just an emissions compliant oil warmer? Decisions decisions!

[STiPWRD]

Others probably have a better explanation but here is my simple understanding:

The factory "oil cooler" is an oil-to-water heat exchanger that is meant to maintain proper oil temp. It has nothing to do with emissions, the water is there to heat the oil to the proper temperature under idle and in cold weather. The right oil temperature is important because it affects oil viscosity and other parameters that determine bearing lubrication, wear, etc. Under performance driving when the engine is very hot and the oil heats up, the water cools the oil back to where it needs to be. So it can be both a cooler and a heater. If you plan to track the car, the stock "oil cooler" may, or may not, be adequate for cooling. You could datalog oil temp and figure out if you really need an aftermarket oil cooler.

[Scargo]

Ha ha... Here I go again. That oil warmer is in HELL (fire and brimstones down there)! So is the filter.
Mine has been a 395 WHP/393 FPT engine with a forty row, 12 X 12 X2 Setrab cooler in front of my driver's wheel with no direct airflow or fan. I have a big Ron Davis radiator. I do have a closed-vane SUB 21111AA026 water pump. I have a remote filter and a nine quart system. I have never had any overheating issues or oil-related failures.
I have my engine work done by Larry's if I don't do it myself. I trust them, but their's is just anecdotal information and it's one person. They could have had air in the system at one point. If an elephant had been walking by when they unknowingly fixed the problem they would have then credited the elephant. That's my take.
My racing buddy is Steve Hanford, a long time Connecticut instructor and track day guy, who drives his Subies hard and keeps up with much more powerful cars. He ditched his cooler/exchanger long ago. He gets great life from his 370 WHP range motors and no cooling problems. He has a simpler system than mine.
Larry's does his motors, too. I just helped Steve build up a new SB that Larry's did. Larry's did my 2.3 L destroker machine work not long ago. I know Kenny Carlson is a great Subaru engine builder and machinist but I don't believe he or Larry's are involved in any racing programs.

[lance corsi]

Its a heat exchanger. Sometimes it heats and sometimes it cools. The FSM calls it an oil cooler.

[tmoretta]

Thanks for the clarification guys. Hey - I am thinking of mounting my oil cooler in the engine compartment - above the level of the engine. It will be in the upper part of the box I made to isolate the air intake (behind right side vent opening). Any problem with the oil pump pushing the motor oil above the engine?

[Scargo]

Any problem with the oil pump pushing the motor oil above the engine? I doubt it unless you have a wimpy stock 10mm pump...
It would help me (to give you better than a flip answer) if you would regurgitate what your engine and oiling system consists of. There are so many factors.

[tmoretta]

It is a slightly massaged engine (no tumbler valves, 272 degree cams, VF 39 turbo, tuned to about 260 HP. Currently being rebuilt - and, I will go to the 11mm oil pump, and AWIC. I have a 13 row Setrab oil cooler - AN 10 hoses added later.

[Lumpyguy]

I would like to know what everyone is doing about the stock heat exchanger between the block and the fillter. what is needed to romove this to install the sandwich plate for the coler lines? what caps for the old coolent lines? what about the mounting stud that hold the sandwich plate on? do you need a new one or remove the old heat exchanger and put on the sandwich plate?

a good write up on how to remove and install the plate would be great.

[Scargo]

Lumpyguy, Can't do research on the posts and links just this moment but I have covered it here on the 818 forum.

To tmoretta, I suspect you would be well served by adding one more shim (for a total of two) if you have normal to race-loose clearances. I don't think you will have any issues with slight elevations.

[Bob_n_Cincy]

I would like to know what everyone is doing about the stock heat exchanger between the block and the fillter. what is needed to romove this to install the sandwich plate for the coler lines? what caps for the old coolent lines? what about the mounting stud that hold the sandwich plate on? do you need a new one or remove the old heat exchanger and put on the sandwich plate?

a good write up on how to remove and install the plate would be great.

Lumpyguy,
I went with an external liquid/liquid heat exchanger. You can see what I did here.
http://thefactoryfiveforum.com/showthread.php?12534-MRG-MotorSports-818S-Build&p=248598&viewfull=1#post248598
Bob

[tmoretta]

Excuse my ignorance. What shim are you commenting on? Something in the oil pump?

[Scargo]

Excuse my ignorance. What shim are you commenting on? Something in the oil pump?
Yes. All Subaru pumps appear to come with one shim inside, where the pressure relief valve resides. Most performance oriented people upgrade to an 11mm pump if they don't have one already. Most Sti's come with an 11mm pump rather than a 10mm pump. I am trying a 12mm pump on my new race motor with an external pressure relief valve. I cannot recommend a 12mm pump! I can recommend upgrading to an 11mm pump.
On top of that they generally add a second shim. Shims are 1mm thick. This raises the maximum oil pressure. Some who build racing motors may add a third one. You can increase the pressure by thinning the crush washer or by changing the spring, among other things. Shimming is fairly straightforward and washers can be found that are thinner than 1mm. It is about a .5" OD washer.

The problem with all this is the oil pump's pressure relief valve is hard to get to. You have to pull the radiator, belts, timing covers, crankshaft pulley and timing belt just to get at the plug in the oil pump that holds the spring, shims and piston in place. Then you guess at how much you want to shim it. It is just a guess as to how much thickness change does what. I have never seen anyone say what X thickness change does for you. Usually they talk in terms of adding one or two shims.
Another method to affect the oil pressure to some degree would be to change oil weights.

[tmoretta]

Thanks for the info. Since I am in the midst of an engine rebuild and changing the oil pump it will be easy. I will change to the 11mm and see a about adding one additional shim. I also will see what Larry's Machine shop says.