QUOTE(9146986 @ Oct 19 2004, 06:23 AM)
I call the line that connects to the bottom of the tank (in the bottom of the fender well) and goes to the tube on the bottom of the oil cooler the suction side. And the side that comes out of the side of the crankcase the pressure side.
aha.
i think we'd all agree on your use of the term 'suction side.' - that's the inlet to the pressure side of the oil pump and not a good place to plumb any kind of restriction.
what you've called 'the pressure side' tho is what most of us call the 'scavenge circuit' -- that's the output of the scavenge pump, and is the line most-often used to feed a thermostat/cooler (since it is hottest, and the scavenge circuit is less critical.)
scavenge oil, tho, is pretty foamy, which makes it less efficient to cool.
the factory on-engine cooler is in what's conventionally called 'the pressure circuit' - that's the circuit that runs from the inlet (the suction line) from the tank through the pressure (smaller) side of the oil pump, to the stock thermostat, and possibly through the on-engine cooler before going to the bearings.
since this oil has been de-aerated by its trip through the oil tank, cooling is much more efficient.
the factory race cars (and 993) put another filter there instead of an on-engine cooler. there are port plates available that bolt up in place of the stock cooler and let you run whatever additional pressure-side filtration and cooling you require. all 993 and factory race cars have BIG front mounted oil coolers, and the 993's incorporates at least one fan to cool the oil in traffic.