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Discussion Starter · #1 ·
As an experiment, I blocked off both oil cooler inlets on my '06 Exige and experienced about a 20 +/- degree increase in oil temperature to 165 - 170 degrees per the Autometer electrical temperature gauge installed. (My car has OEM dual coolers, the oil temperature sensor is located in the sandwich plate, the car was driven for about 40 suburban miles in 50 degree ambient temperature and fluids were as warmed up as there were going to get.)

I did the experiment after reading the various oil line recall and rear oil cooler posts, where some owners were contemplating disconnecting their cars' oil cooler(s), and wanted to see what oil temperature change would occur with the oil coolers in place but with no air flow through the coolers...passive heat dissipation.

Back to the experiment: I expected to see a bigger oil operating temperature gain with no air circulating through the oil coolers, and it leaves me wondering if the 25 +/- feet of oil hose is providing incremental passive cooling, too.

I'd like to achieve oil temperatures of 225 degrees +/- (assumes 75 degree ambient temperature) but am wondering if that is even possible with a rear mounted oil cooler.

For owners that have installed a rear mounted oil cooler:

What is the typical oil operating temperature of your car versus ambient temperature?

What brand of oil cooler and cooler size is installed in your car?
 

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Interesting post, as just today I ran my Elise after changing to a rear cooler for the same reason you are thinking about it. Not on the road, just in the air, on jack stands with no rear clam. What I found interesting was that within minutes of starting, before the temps even showed on the coolant gauge, the oil cooler was getting hot, and when the dash temp popped on at 158 deg. the oil cooler was almost too hot to hold, even tho the Autometer pan mounted sender/gauge only registered 145. It's clear that the oil therm. is letting a lot of oil circulate, and/or is stuck open, as the oil temp was no where near the 162 that supposedly begins to open at. Will be interesting to see on the street how the temps go...
 

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Even with the openings blocked off, there's plenty of heat dissipated through the coolers. The lines are contributing as well. You're not really testing the same thing as totally removed coolers.
 

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Interesting post, as just today I ran my Elise after changing to a rear cooler for the same reason you are thinking about it. Not on the road, just in the air, on jack stands with no rear clam. What I found interesting was that within minutes of starting, before the temps even showed on the coolant gauge, the oil cooler was getting hot, and when the dash temp popped on at 158 deg. the oil cooler was almost too hot to hold, even tho the Autometer pan mounted sender/gauge only registered 145. It's clear that the oil therm. is letting a lot of oil circulate, and/or is stuck open, as the oil temp was no where near the 162 that supposedly begins to open at. Will be interesting to see on the street how the temps go...
Oil tStats don't open the loop to the coolers, rather they close a bypass route, thus forcing all oil through the coolers.
When the stat is closed (oil below temp), oil will flow through the coolers as well as through the bypass, the idea being that the bypass has less restriction than the coolers and thus more oil will flow via the bypass.

Even with a Laminova as I have, it's difficult to get the oil temps much above 180 under moderate loading.
 

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Discussion Starter · #5 ·
Even with the openings blocked off, there's plenty of heat dissipated through the coolers. The lines are contributing as well. You're not really testing the same thing as totally removed coolers.
Correct, that was the point of the experiment.
 

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I used a Earls type, 10 by 5 by 2in. core, with -10 ports, located in the pass side grill opening. Only took 4 ft. of line total, and will be easy to partially block if it turns out my temps are still too cold. Thanks for the explanation on oil routing, makes sense.
 

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Discussion Starter · #10 ·
I used a Earls type, 10 by 5 by 2in. core, with -10 ports, located in the pass side grill opening. Only took 4 ft. of line total, and will be easy to partially block if it turns out my temps are still too cold. Thanks for the explanation on oil routing, makes sense.
Great information, and very nice and clean installation! Your Earl's unit sizes out to be comparable to the Setrab 6 series 16 row cooler and the Mocal 235 series 16 row cooler, which is similar to other installations (including 19 row coolers) that I have seen in postings.

I am interested in knowing the sizes of rear coolers being used and operating and ambient temperatures because a smaller cooler unit might get the higher oil temp I am targeting as well as allowing a more compact installation.
 

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Thanks! A 1 or 2 in. narrower cooler would be very easy to package, and where I live would probably work fine. I will see next Summer how this size works, but I do like the elimination of around 23 ft. of line, and whenever the fnt. clam comes off, the pair of coolers.
 

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Discussion Starter · #12 ·
I was hoping to get reports of actual temperature data from people that made the rear oil cooler conversion...but seems they just ain't talkin'!

So, I have ordered bits for a rear oil cooler kit for my '06 Exige N/A based on a 13 row Earl's Temp-A-Cure unit sized for the btu output of a 190 hamster-powered engine, Aeroquip Starlite 10 AN hose and fittings, and 5/8 BSP to 10 AN male unions to retrofit the OEM sandwich plate. I plan to fabricate brackets using 6061 aluminum plate and flat metal pieces. I will plug the OEM oil lines and leave them in place after the rear cooler conversion until I remove the clam at sometime in the future to upgrade the radiator.

I'll report back sometime in the future with temperature data.
 

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I'm wondering if the advice to only go single cooler applies to supercharged cars as well. It seems pretty clear now that NA cars should only have one cooler. Anybody have any data on the Elise SC, Exige S, S240, and S260? Is there a crossover point where dual coolers is useful?
 

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Discussion Starter · #15 ·
Hard data on temps

I completed the installation of a rear oil cooler, made an extensive test drive and have hard data to report.

Oil cooler set up: Earl's 13 row Temp-A-Cure cooler, Aeroquip 10AN hose ends, Aeroquip Starlite hose, brackets fabricated from 6061 aluminum. I mounted it in right rear wheel above the scoop inlet (see picture) so that it would be out of the way of the A/C line nipples, not impede air flow into the engine bay, and be cooled by the updraft of air from the scoop and turbulent air from the wheel well liner.

Conditions: Ambient temperature was 65 degrees, sunny, and 52% humidity. Test drive was over a 40 mile route with about 1/2 the distance on freeways at 65mph average and 1/2 was suburban (flat and foothills) at average of 35mph when moving, with total drive time of about 50 minutes. My 2006 Exige is N/A with no engine mods.

Oil operating temperature: ranged from 0 to 8+/- degrees ABOVE engine operating temperature, which means oil temperature ranged from 190 to 198 and engine coolant temperature of 188 to 190 degrees.

Observations: car is faster to warm up, has higher oil pressure, finally has sensible oil operating temperatures, and the body work above the cooler only gets slightly warm to the touch (I do plan to install an adhesive heat reflective panel above the cooler anway).

This is a big improvement...before with the OEM dual coolers, I would have seen oil operating temperatures consistently at about 160 to 165.
 

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In reading this and remembering something I read elsewhere I've come to wonder about this... Oil *flow* is really what is important (this is what I read elsewhere). if it flows well, it lubricates, and cools the parts it's supposed to. If it doesn't flow well bad stuff happens. It seems that while raising temps might increase flow, it also sacrifices cooling power. So wouldn't the other way to attack this problem (if one thinks that one isn't getting enough flow) be to change the oil viscosity? Perhaps I have this all wrong?:scratchhead:

The weight savings of this mod are obviously attractive, but someday I'm going to get to the point of tuning the engine, and then excess heat will be the enemy...
 

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In reading this and remembering something I read elsewhere I've come to wonder about this... Oil *flow* is really what is important (this is what I read elsewhere). if it flows well, it lubricates, and cools the parts it's supposed to. If it doesn't flow well bad stuff happens. It seems that while raising temps might increase flow, it also sacrifices cooling power. So wouldn't the other way to attack this problem (if one thinks that one isn't getting enough flow) be to change the oil viscosity? Perhaps I have this all wrong?:scratchhead:

The weight savings of this mod are obviously attractive, but someday I'm going to get to the point of tuning the engine, and then excess heat will be the enemy...
That isn't quite right because 1) oil is often engineered to operate at a certain temperature, and being far outside that range isn't great, and 2) the viscosity of even cold 0W20 weight engine oil is way thicker than that of an operating temperature 5W40 weight engine oil. Thus, either way, you're going to have thick oil if your weight temperatures are too low.

Also, see my observations of the operating temperatures with the BOE side mount cooler: http://www.lotustalk.com/forums/f25/boe-fabrications-side-mount-oil-cooler-342921/#post4524873
 
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