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Discussion Starter #1 (Edited)
I completed the installation of a rear oil cooler and removed the OEM oil lines from the sandwich plate to the OEM dual coolers on my 2006 Exige (N/A with no engine mods).

Note: this is not a beginner's DIY project. It requires the installer to have the skills, facilities and tools to fabricate parts, take apart the car's OEM oil cooler system and replace it with a brand new aftermarket installation that works as intended, be able to problem solve and independently think along the way. The parts that are appropriate for your car may differ from the ones that I selected and installed.

Tip: drain the engine oil, remove the oil filter, and disconnect the oil lines the night before so that as much oil is evacuated from the engine and oil lines as possible.

Oil cooler installation
Parts used:
- Earl's 13 row Temp-A-Cure cooler with 10AN connections (sized for my car's engine configuration)
- Aeroquip Starlite 10AN hose ends (three 90 degree and one 45 degree elbows)
- Aeroquip Starlite hose (five feet)
- 6061 aluminum panel for fabrication of brackets (1 sq.ft.)
- 6061 aluminum bar (3/4 inch wide x 1/8 inch thick x 1 foot) for fabrication of bracket
- 5/8" BSP to 10AN male union (for OEM sandwich plate)
- 5/8" Dowty Seal for BSP port (for OEM sandwich plate)
- BSP Plastic Flare Caps (threaded, not push-on type)
- 6mm x 20mm screws, 6mm washers, nylox nuts and rubber grommets to vibration dampen and attached cooler to brackets)

I made a card board mock up of the oil cooler for the purpose of deciding where to install it...standing and angled back just forward of the wheel well liner or stuffed into the cavity of the scoop inlet channel...and realized that there was a big empty void in the space above the A/C service nipples just to the outside of the roll bar diagonal extension.

I planned to mount the cooler in the right rear wheel above the scoop inlet so that it would be out of the way of the A/C line service 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 (see picture). The oil inlet port of the cooler would be located toward the rear of the car and the outlet port to the front.

For purpose of attaching brackets to each of the four oil cooler tabs for vibration dampening, I inserted rubber grommets into the cooler tab holes and threaded in 6mm x 20mm hex head screws, a 6mm washer on each side, and a nylox nut to keep everything tight. Note: take into account the thickness of the rubber grommets when fabricating brackets.

I fabricated the front bracket so that the one end of the cooler was hinged and the oil inlet hose end of the cooler could be lowered and the cooler filled with oil and primed before attaching the oil return hose. For bracket attachment points, I used the engine mount bracket on the back of the roll bar diagonal extension to attached to the left rear tab of the cooler, one of the side clam attachment screws to attach to the right rear tab of the cooler, and a pre-existing 6mm threaded nut inserted by the factory in the rear clam behind the door jamb area (see picture) to attach to both ends of the front of the cooler.

Once the oil cooler brackets were fabricated, I dry mounted the cooler to make sure it was secure (solid as a rock), temporarily screwed on the AN fittings to the cooler as well as OEM sandwich plate and measured hose length for the oil lines. For my particular installation location, five feet of hose was exactly the correct length to yield both hose lengths - maybe an excess of one inch to spare.

Before final installation, I did a full dress rehearsal with the cooler, hoses and fittings assembled, and all brackets, fasteners threaded through rubber grommets to confirm that the cooler was solidly mounted, hose ends were correctly clocked, and hoses were routed away from the fan belt and not stretched or kinked.

For final assembly, I bench installed the AN hose fittings onto the cooler, installed the BSP adapters with Dowty seals on the OEM sandwich plate (note: first install the oil return port adapter, and then install the oil outlet port - otherwise tool access will make it a PITA). I only attached the front cooler bracket to the car and positioned the rear of the cooler in a lower position from horizontal, and then I pulled the oil return line through the engine bay and used it (with a funnel) to fill the oil cooler and inlet line for priming before engine start up (see Lotus manual for oil line bleeding procedure). With that done, I attached the oil return line, double checked every fitting, fired it up and let the engine run at idle for at least 5 minutes to circulate oil through the lines.

Removal of OEM lines
Once I verified that the rear cooler was functional without problems, I removed the OEM oil lines from the sandwich plate to the OEM dual coolers and capped them with BSP caps. I'll remove the OEM coolers and cross hose at a later date the next time the clam is off. At that time, I'll relocate the Stebel Nautilus horn that I previously installed in the OEM location into the passenger side oil cooler area and attach it to the oil cooler frame. Relocating it from the crash box area should make the already loud horn even louder!

Removal of the OEM lines is straight forward but a serious PITA. For both sides, remove the front wheels, wheel well liners, and interior door sill covers, and release the hose clips in the wheel well areas. I chose to cut the oil lines in the wheel wells as close to the cabin as possible and had an oil pan handy (and covered the brake discs for protection) just in case any oil spilled out. With the driver's door sill panel removed, I reached into the door hinge recess opening and reached back and downward to release the oil hose from a metal clip on the outboard side of the bodywork, and then I reached forward to find the hose and pulled it downward through the fender panel opening. Going to the back of the car and down low in the engine bay, I reached into the rear of the sill cavity and released a plastic clip securing the oil hose. Then, I pulled on the oil hose and worked the full length of the oil hose with its foam sheath (now shredded) out of the car. The drill was the same for the passenger side, but be aware that removal of the passenger side oil hose is more difficult and a double PITA because the metal A/C lines make access to the sill cavity difficult and block the route for oil hose removal. I chose to cut the oil hose, curl it inward into the cavity and rerouted it back out so that when I pulled on the oil hose the A/C lines would not be stressed.

Test drive
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 anyway and cut an hot air ventilation gap along the top of the engine bay passenger side trim panel).

Before with the OEM dual coolers, oil operating temperatures were consistently at about 160 to 175 degrees depending on ambient temperature with 200 only reached during track days in 100+ degree heat.
 

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He's on fire!
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Please update when you take out to the track! While I'll probably leave my lines, it would be nice to see what temps this works under.
 

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Siver_Surfer and I were just talking about doing this. Thanks for posting the parts you used!

I am curious about the performance in warmer temperatures. It doesn't look like the heat exchanger will see much airflow to cool the oil. Did you mount the cooler there for any particular reasons?
 

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Discussion Starter #4 (Edited)
Almighty: yes, I mounted the cooler in the right rear wheel above the scoop inlet so that it would be out of the way of the A/C line service nipples, not impede air flow into the engine bay, and be cooled by the updraft of air from the scoop and bouncing off the wheel well liner.

It is a small space with a lot of turbulent air, heat rises, and my thought was that it would likely get as much upward flow-through ventilation as if it were mounted between the A/C nipples standing at a 75 degree rearward rake with incoming air at a 30 degree angle. After spending time considering various mounting positions, I concluded that any mounting position would involve compromised air flow.

Relocating the cooler into another position, if necessary, would just require fabricating new brackets since both oil lines are long enough.

Though, my car is an Exige and it's rear fender area and wheel well area are open to the engine bay. Air flow considerations might be different for an Elise.
 

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Discussion Starter #5 (Edited)
Please update when you take out to the track! While I'll probably leave my lines, it would be nice to see what temps this works under.
I would expect high temps of 220 to 230 degrees during track sessions in 100+ degree summer weather. If not, then I can either install a cooler mounted fan to increase air flow, change the cooler location, or go to a bigger oil cooler.

Yank your OEM lines and replace them with quality lines and fittings even if you want to retain the OEM layout. While at it, put a higher quality (and lighter weight) cooler in place of the OEM one(s) if you stay with the factory layout.

I had declined the oil line recall work since my car's oil lines did not appear to have issues after 30,000 miles including 2,000 mile on-track and I planned on converting to a single rear cooler. Note: the OEM fittings and lines appeared fine upon inspection after removal. Though, the OEM fittings and lines are bulky, weigh a ton, and their quality, reliability and durability have been deemed suspect enough to warrant a recall.

I feel more confident knowing the high quality of the hose ends / fittings and oil lines now in the car, and improved quality benefits both an OEM oil cooler configuration or aftermarket rear cooler set up.
 

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Damn good write up. I too am interested in on track results, though it'll be a few months before it's warm enough.
 

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Excellent, thank you!

I'm getting ready to go to a single rear-mounted cooler also. I'll snap some pics and maybe start my own thread :up:
 

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Does anyone know how much more efficient this oil cooler is than the stock OEM ones? Can the stock Oil Coolers be relocated to the back passenger side intake or is it that bad? I want to take off both of my front OEM oil coolers and hook up one of them in the back, any feedbacks?
 

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I was considering relocating the OEM cooler to the rear as well, but the hose attachment points may not be optimum. Oil coolers are not that expensive (Setrab) so why not get one that will fit great and perform better than oem.
Aftermarket coolers come in many shapes and configurations so it would be easier to make it fit than adapting the oem to fit well.
-Robert
 

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Discussion Starter #12
Does anyone know how much more efficient this oil cooler is than the stock OEM ones? Can the stock Oil Coolers be relocated to the back passenger side intake or is it that bad? I want to take off both of my front OEM oil coolers and hook up one of them in the back, any feedbacks?
The key issues for locating an oil cooler in either side intake area are: size dimensions of the cooler; cooling capacity; weight of the cooler; hose inlet and outlet locations; routing of oil lines. I think you'll find that the OEM cooler will certainly fail for relocation purposes in terms of: size; inlet and outlet locations; weight savings. You'll need to find out the BTU rating for an OEM cooler to compare it to aftermarket coolers.

The primary reason for (my) setting up a single oil cooler to the passenger side inlet was to get my Exige's oil temperature up to a sensible operating range, so I ditched the dual cooler set up and went to a single cooler set up. Oil operating temp has increased about 25 degrees on average to around 195 but is still arguably a bit low even with a single cooler correctly sized for an N/A 2zz-ge.

The secondary reason was to simplify the oil cooler system by ditching the miles of hosing, weight, and additional connection points of a dual cooler set up.

Relocating dual OEM coolers to the rear would make no sense IMO since you'll retain the over-cooling capacity and added plumbing complexity of two oil coolers and you'll add brain damage and time required to relocate it all to the rear. :shrug:

Having converted to a single oil cooler set-up using after-market parts that are of higher quality than the OEM bits, I would not even entertain adapting and re-using the OEM oil cooler (a quality oil cooler depending on size will cost about $200 +/-). You'll still have to buy hose and hose ends. I suppose you could adapt and re-use the bulky OEM oil lines to keep costs down, but that would IMO just add to the re-engineering brain damage factor and defeat the benefit of achieving weight savings when converting to a rear oil cooler. :facepalm
 

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Looks nice!
 

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Discussion Starter #15
Yes, oil temp ran about 230 degrees on track at Streets of Willow on Monday, 3/17/14, which was about 30 degrees higher than engine coolant temperature.

Ambient temperature was 67 degrees, 17% humidity, very sunny, 20 minute run session on a tight street course with plenty of elevation changes, and the passenger side engine bay trim panel was removed so heat could easily rise from the oil cooler.
 

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Yes, oil temp ran about 230 degrees on track at Streets of Willow on Monday, 3/17/14, which was about 30 degrees higher than engine coolant temperature.

Ambient temperature was 67 degrees, 17% humidity, very sunny, 20 minute run session on a tight street course with plenty of elevation changes, and the passenger side engine bay trim panel was removed so heat could easily rise from the oil cooler.
What do you estimate would be the temperature on a 100 degree day? And you are running NA right?
 

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Discussion Starter #17
What do you estimate would be the temperature on a 100 degree day? And you are running NA right?
Yes, N/A.

I wouldn't want to even guess...too many variables to account for...but I'll find out this summer.
 

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What happened to your AC brackets? They look indented.

BTW: Do you track your car regularly?
 

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Discussion Starter #19
What happened to your AC brackets? They look indented.

BTW: Do you track your car regularly?
The A/C bracket and lines are fine - just an optical illusion. I saw the same when first looking at the photo. It is just curvature of the tubing, the black caps and lighting playing mind games.

No, I am an occasional tracker - maybe two to four times a year.
 
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