Rear Mounted Oil Cooler

[Locobob]

Originally Posted by Hib Halverson

BAD IDEA!

1) Not only will there be pressure drop with 20 linear feet of hose but any place the hose or line turns a corner, the pressure drop increases. A 45° bend has about a much restriction as 5-feet of hose. A 90° bend has as much restriction as 10-ft. of hose. Years ago, I installed an oil cooler and remote filter on a Big-Block C3. The hose run was only about six feet total. The oil pressure loss was so much, I had to shim the pressure relief in the oil pump and even then there was still 10-15 psi less than before I installed the cooler.

2) At engine start, it will take a long time for oil under pressure to reach the bearings.

3) As engine speed increases, there will be a lag in oil pressure increase.

4) Inertia...as you accelerate oil flow will decrease. That's the last thing you want as RPM increases. Vehicle acceleration aside, the engine oil pump is going to have to work really hard to move the amount of oil in those lines and work even harder when it has to accelerate oil flow.

5) Complexity. Running two oil lines from the front of the car to the rear is going to be a big job. Also, if you think you can run two straight hoses all the way back, think again, then re-read #1 above.

6) Weight. You will not gain anything in a practical sense. Yes, you may move the CG of the car fractionally to the rear, but the overall weight of the car will increase with all that hose, fittings and extra oil.

7) Oil capacity. Get 20-ft of AN-12 hose. Plug one end. Fill the hose full of water then drain the water in to a half-gallon jug and see how much you have. I'll bet it's a lot more than you think.

Thanks for the input Hib.


I've been doing some more research and here's a few things I discovered.


The factory oil cooler is quite large and has a total of about 15 feet of .78in OD piping.... 6 rows of horizonal pipes are bracketed by the in and out vertical pipes. I'm not sure how that stacks up pressure wise when compared to say a 15 foot straight run. I talked to tech at Derale and was told that the factory system is not a very efficient design by todays standards. It may be possible that a smaller but more efficient cooler combined with a longer hose run may not be all that different in pressure. Probably need a fluid dynamics engineer and testing to know for sure.


As far as point 2 goes my understanding of the system is that the cooler bypass line is temperature activated... therefore on start-up the cooler line is effectively bypassed thus it should have no effect on engine oil pressure at that time. If you have information to the contrary I'd like to see it. Routing a cooler off a remote oil filter line on a big block would be a whole different ball game as it sounds like oil would flow through the cooler 100% of the time.


Weight of about 20ft of line would be 3-5lbs dry depending on the size and type of line... but a smaller aluminum cooler should be lighter than the stock one. Fluid weight would depend on the capacity of the new cooler and added lines vs the stock system... I don't think its really feasible to drop overall weight, probably a wash at best. The main benefit would be moving weight rearward.