oil cooler adaptors, 3/8 vs. 1/2 inch sandwhich style Options

[realred914]

looking for a good sandwhich adaptor to add an oil cooler. want one with a thermostat built in, I see several brands for sale, there are some big price differances too.

at any rate there are some ones that have 3/8 inch NPT inlet/outlet threads, and others that have 1/2 inch NPT threads inlet and outlet. the price differenace is considerable (nearly 3X)

seeing as the oil passages upto the filter are not all that fat anyway I figure, how much benifit would one get out of a 3/8 NPT fitting verses the 1/2 NPT? I still plan to use AN10 hose and fittings and have 1/2 inch NPT on the oil cooler itself, so the biggest restriction in the new system would be the 3/8 NPT fittings on the sandwhich adaptor. will this be a significant flow restriction or not verses the larger adaptor? the engine will be a daily driver motor, not a high rpm race motor.

[charliew]

I was always under the impression that any oil line should be as large on the id as any oil gallery that the pump feeds or bigger if the lines are long to prevent the oil from being restricted. When the oil is restricted it gives a false oil pressure reading at the bearings but that is only on a full flow oil cooler system not a bypass oil cooler system. On the bypass oil cooler I would still want at least 1/2 id oil lines. 10an is 10/16 or 5/8 id.

My shade tree math is as follows: 1/2 is 4/8 therefore 3/8 is 25% less volume than 1/2 not counting the wall restriction.