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.

[32valvZ]

What about plumbing hard lines, and not rubber hose? Might help with pressure loss because its rigid, and maybe smaller I.D. Also, less chance of damage. I realize this could be harder to accomplish... just thinking out loud...

[XfireZ51]

Hib is saying that the “lag” in such a system could be like “turbo” lag only detrimental to the motor. Takes too long for oil pressure to respond to requirements of the moment, ie WOT. Dry sump for the LT-5 would have been very interesting.

[Jagdpanzer]

Bear in mind the LT5 oil cooler circuit is has a thermostat control valve that begins opening when the oil temperature reaches control range. It directs just enough oil through the oil cooler to maintain proper temps. During normal street driving probably not much oil flow is sent through the cooler as the engine heat loads are not very high. Instead most of the flow goes directly to the engine mixed together with low volume of cooled oil coming from the cooler. The oil heat load increases when more power is produced like at the track. The oil cooler thermostat valve reacts by directing more oil through the cooler while at the same time reducing the volume of uncooled oil going directly to the engine. The engine sees the same over all flow however, more of it has passed through the oil cooler.

[Locobob]

Originally Posted by Jagdpanzer

Bear in mind the LT5 oil cooler circuit is has a thermostat control valve that begins opening when the oil temperature reaches control range. It directs just enough oil through the oil cooler to maintain proper temps. During normal street driving probably not much oil flow is sent through the cooler as the engine heat loads are not very high. Instead most of the flow goes directly to the engine mixed together with low volume of cooled oil coming from the cooler. The oil heat load increases when more power is produced like at the track. The oil cooler thermostat valve reacts by directing more oil through the cooler while at the same time reducing the volume of uncooled oil going directly to the engine. The engine sees the same over all flow however, more of it has passed through the oil cooler.

Yeah this was my understanding of the system. If I remember correctly it is never the case that 100% of the oil goes through the cooler

[Locobob]

So I may have come up with a better solution to lightening up the front of the car:
https://beta.rondavisradiators.com/p...ne-oil-cooler/
I just got off the phone with Ron and he says this radiator with the built in oil cooler is only about 2-3lbs heavier dry than their normal C4 radiator. Now the oil cooler displaces a little coolant so its probably about the same weight wet as the standard RD radiator.... which means I could save a full 11.5lbs by ditching the stock oil cooler. I currently have an old RD radiator in my car so it would pretty much be a drop in save for routing the oil cooler lines. Now the oil cooler capacity on this is quite a bit less than the big stock unit but water cooling is inherently more effective than air cooling so that could offset the reduced capacity. I'm thinking it would probably be fine given that my oil temps normally barely move off the needle. The only time I've seen oil temps come up a bit is on track days and I haven't done one of those in years.

[A26B]

Robert,
If you decide to go this way, here is some info for you to consider.

Edelbrock-Russell ProClassic II hose is much lighter than the typical braided SS of the same size. Using crimped fittings is less bulky & looks cleaner.

I only use -10 (5/8") hose for the Oil Cooler Hoses we make in house. If you can make the RD radiator connection -10AN male, I can help you with the custom hoses. Get an approximate length & I can send you a piece of hose to use for obtaining the actual overall length of each hose. Send it back with the overall lengths. I stock 90 deg swivel & straight crimp fittings. Look on my website to see the hose & fittings.

Might be able to trade in your OE Oil Cooler on the new hoses if you are interested.

[Locobob]

Originally Posted by A26B

Robert,
If you decide to go this way, here is some info for you to consider.

Edelbrock-Russell ProClassic II hose is much lighter than the typical braided SS of the same size. Using crimped fittings is less bulky & looks cleaner.

I only use -10 (5/8") hose for the Oil Cooler Hoses we make in house. If you can make the RD radiator connection -10AN male, I can help you with the custom hoses. Get an approximate length & I can send you a piece of hose to use for obtaining the actual overall length of each hose. Send it back with the overall lengths. I stock 90 deg swivel & straight crimp fittings. Look on my website to see the hose & fittings.

Might be able to trade in your OE Oil Cooler on the new hoses if you are interested.

Sounds like a plan Jerry, my radiator and everything around it is about 15 years old now so wouldn't hurt to freshen things up. I'll probably do some of your red silicon hoses as well. Probably going to be a winter project as I don't want my car down with the weather being nice here.