After 4 months of rigorous testing including 4 track days and sixteen 20-25 minute sessions, I can confirm this design and implementation works very well. The other rear differential cooler options available thus far have been a rear mounted solution requiring fans. Not only are they aesthetically unattractive (unless you like seeing the HX and fan hang beneath your car), the airflow beneath the car is heated.
This solution takes into consideration the following goals; nothing visible beneath the car, no fan required, and significantly increase the rear differential fluid capacity from OEM 50-55 ounces.
Mounting a Setrab 10 row oil cooler in the grill with a Turbowerx Exa pump also mounted in the front of the car directly behind the head lamp, nothing is visible from the rear or front of the car. Running AN-10 line with push lock fittings from the differential to the inlet of the pump and out to the HX, the full size Turbowerx pump (3GPM/350* rated max temp) easily handles the long 13ft. prime distance from the diff to the pump. An inline filter is installed in the feed line near the banjo fitting out of the diff for easy cleaning when changing diff gear oil. Out of the HX returning to the differential fill inlet AN-08 push lock fittings and lines is used. A Setrab thermal switch engages the pump when rear diff oil reaches 180* and disengages when temps drop to approximately 170*.
For testing and development purposes, an oil temperature gauge was installed in the return line immediately coming out of the grill mounted HX. Knowing the inbound oil temp was at least 180, monitoring return oil temps measured the effectiveness of the HX.
1. Rear differential oil capacity increased by over 100% from about 55 ounces to over 120 ounces - almost 4 full quarts.
2. Under normal daily driving conditions in 60-70 ambients, diff oil temps rarely triggered the thermal switch unless 45 minute or more freeway speed runs (75-85MPH) took place. 30-45 minute commuter speed or local low speed traffic never reached 180*
3. With higher ambients and/or longer duration highway trips when the thermal would trigger the pump, the return oil temperatures averaged 125-135*. When the car was parked and engine shut down, the pump would typically run another 2-4 minutes maximum before shutting itself down.
4. At Auto Club Speedway in Fontana in March, 2013, ambients were in the mid to high 80’s track temp estimated to be 95-100*. Auto Club Roval configuration is 17 turn fast track with the front straight speeds hitting the 145-160MPH range. Two other WOT straights average 110-130MPH. During the hottest session of the day (ambient close to 90*), in the pits immediately after a 20 minute 11 lap session, return oil temperature peaked at 166*; previous sessions were in the 145-155* range. Pump turned itself off within the same 3-5 minute window. At Willow Springs in April, similar results with my car and one other car running the same set-up, except return oil temps were lower given the lower 55-65* ambient temps.
Overall very pleased with the results, effectiveness and aesthetics of the kit. Lines to and from the diff can be run tucked up along the frame rails or combined with the fuel line race for both feed and return lines. Exhaust was wrapped with header wrap beneath the diff to shield the diff from exhaust heat and shield the AN lines that cross over the exhaust. A self-adhesive heat shield tape on the short portion of AN line from the fittings to beyond the exhaust can also be applied as an extra measure.
Installation is fairly straight forward; HX can be mounted directly to the top of the bumper or a bracket can be made from straight aluminum stock. Pump typically installed on driver side and clears the longer CAI implementations that utilize the 14” green filters and long down tubes. Front clip does need to be removed for install. A reasonably competent DIY can usually complete the install in about 5-6 hours. The most time consuming part of the install reported has been running the lines. Except for the Turbowerx pump and the adapter to install the thermal switch in the differential, everything else is Setrab components. Hose fittings are all push lock; Aeroquip and Setrab specifically recommend against using hose clamps on these fittings. Test car #1 has zero clamps and zero leaks or drips after 4 months and 4 full track days
Kits are now being offered and can be modified to use stainless lines and fittings if desired as well as larger oil coolers to further increase oil capacity and cooling.
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