Rear Mounted Oil Cooler

[Locobob]

Originally Posted by spork2367

I'm not sure that moving a couple pounds from the front to the rear, only to add 3-4 lbs total to the car will be worth it.

I haven't had a chance to weigh the stock cooler yet but my plan would be to utilize a smaller lighter cooler in the rear as the extra run of the hose would allow for some cooling as well. Yeah it's not a ton of weight but there's not many options to eliminate or move a lot of weight at any one time on these cars. Mostly its a few pounds here and there that add up.


I'm guessing I'd end up with a slight net gain in oil capacity with a smaller cooler and a longer hose run.


My main concern at this point is finding a viable safe route for the hoses.

[Locobob]

Also I should note that I already have a larger aftermarket radiator, I feel like that coupled with the additional air flow gained by moving the oil cooler out of the radiators path should mitigate a loss in efficiency of the oil cooler itself... which is likely given that the new location would not see as much air flow as the stock location.

[RussMcB]

It sounds like you've already convinced yourself to move forward with this mod, but I'm scratching my head as to why. Seems like there are plenty of reasons not to do it, and no real (noticeable) benefits.

But, I understand it's a hobby and considering mods can be fun.

If it were me I could think of lots of other things (not necessarily ZR-1 related) that would be higher on the list of things to do.

I hope I'm not out of line by giving this idea a public thumbs down. Heaven knows I've done plenty mods I've regretted later. I could give a tour around my garage and point them out. :-)

[Locobob]

Originally Posted by RussMcB

It sounds like you've already convinced yourself to move forward with this mod, but I'm scratching my head as to why. Seems like there are plenty of reasons not to do it, and no real (noticeable) benefits.

But, I understand it's a hobby and considering mods can be fun.

If it were me I could think of lots of other things (not necessarily ZR-1 related) that would be higher on the list of things to do.

I hope I'm not out of line by giving this idea a public thumbs down. Heaven knows I've done plenty mods I've regretted later. I could give a tour around my garage and point them out. :-)

Well I'm not quite there yet. My main goal here is to move weight off the front of the car to the rear which is beneficial to all aspects of performance. But I still have misgivings as this seems to be somewhat uncharted territory. My main concern would be pressure drop in the system, although some cursory poking around seems to indicate that pressure drop through added hose length is somewhat minimal. I'd feel a lot better about it with some expert engineering opinions. I know Graham Behan lurks in here occasionally, if he or some other Lotus/GM/Merc engineers would chime in I'd feel a lot more confident about whether or not to proceed with this. One thing I could do is simply undo the existing plumbing and connect it to about 20' of hose in a circle and see what that does to oil pressure, but to do so would be difficult as I'd have to run the motor hard enough to activate the oil cooler switch.

[RussMcB]

I agree taking weight off the front could/should theoretically help, and Graham (and other smart people here) will have good advice and opinions.

I often forget that many here's main focus is straight line performance, while mine is road racing, and you’d need to be Lewis Hamilton to notice a change like this on a road race track.

[Locobob]

So the oil cooler pretty much full of oil is 11.5lbs FYI... I'm not going to pursue this at this time as its summer and I don't want the car down... but I might look at it again when its time for a radiator or other "while I'm here" service. At some point I'll probably splice in a 20' loop of hose and do some pressure and temperature testing before making a decision on this.

[tnova]

A really easy to do front weight reduction is to replace the battery with a modern gel or even lithium battery. Perhaps the cost of the battery is similar to the cost of a cooler, mount, hoses, and fittings.

[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.

[XfireZ51]

Super insight Hib! Thanks for that clarification.

[Locobob]

Originally Posted by tnova

A really easy to do front weight reduction is to replace the battery with a modern gel or even lithium battery. Perhaps the cost of the battery is similar to the cost of a cooler, mount, hoses, and fittings.

Already have a rear mounted light weight battery