We have written quite a lot about oiling for an RB26, but realized we really haven't discussed oil coolers.
On a stock RB26 there is an oil/water heat exchanger on the right side of the engine. The oil filter attaches to part of the asembly. If you have an R32 with Hicas, you know how fun it is to get to the oil filter.
|RB factory oil cooler. Coolant lines are green.|
We bolded and underlined that last line, because it is very important. If you look at any modern car, or look at any kind of race car, ducting in and out of the core of a cooler is managed. Air is lazy. It takes the path of least resistance. Since you bought the cooler, you want the air packed at the front of it to pass though the core, not pass around it. By adding proper ducting, the air will pass though the core, raising efficiency tremendously.
|R34 N1 with C-West bumper, ARC oil cooler|
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|This picture shows an example of air that is able to flow though a core. In the front, and vented out the back side|
|RB26DETT bottom end|
|RB oil squirters|
There are advantages to this, but most aftermarket pistons don't use this technology. Some guys with big power engines, also eliminate the squirters. They aerate the oil a bit. This is also why the RB has a tendency to move a bit of oil though the PCV system. Oil is all whipped up in the bottom end between the crank, pistons, rods, and squirters.
The next big factor to add heat to the oil are the turbos. Each gets hot. Each adds oil temperature to the mix.
|Exhaust cam cover off|
Then we have two long camshafts in the head. Both also adding some heat to the mix. So if you have been following along, you see the need for an oil cooler. The factory setup works, but by cooling the oil you are also heating up the water. At a point you overrun that system. Over the years we have tried add on water coolers, aftermarket oil/water heat exchangers, and air/oil coolers. We favor the air/oil coolers.
We have eliminated the factory oil/water cooler on one car we had. Cruising at highway speeds, the oil temperatures got a lot hotter than we like. For this reason, we recommend at least a small air/oil cooler if you eliminate the factory setup.