Our take on the FR-S / BRZ / GT86 oil cooler system — more specifically the thermostatic sandwich plate
It all starts with this....a few pieces of aluminum and a thermostatic valve that actuates at a pre-determined temperature. A fairly simplistic idea, but ends up being a bit more complicated than first perceived.
The majority of retailers and even manufactures use the Mocal thermostatic sandwich plate (and why not? It’s a cast component with post machining and a few threaded ports). However, by the time you add up all the components needed to make a complete kit, it gets pricey.
Let’s break down the components piece by piece to look at the basic cost that you might purchase from a retailer:
- Thermostatic sandwich plate (Mocal): $98.50
- Thermostatic spacer, threaded adapter: $70.50
- AN fittings: $7.25 per fitting (2), $13.50 per fitting at Oil cooler (2)
- AN swivel fittings: $15.00 (4)
- AN lines: Typical price is about $6 per foot, and it takes about 7 ft. $42.00
- Setrab 613 oil cooler: $139.00 to $179.00
- Mounting for oil cooler: Estimate, $25.00 to $50.00
Add shipping cost (more than likely the above purchases were sourced from 2 or 3 companies). We will average shipping at $12.95 from each. Estimate: $25.90 to $38.85.
Total: $502.40 to $580.35. This is an estimated price, maybe you will find a few good deals out there and come in less than the above figures. It’s no wonder why you see these kits priced as high as $900.00 plus shipping from certain retailers. While they may be getting a discount, typically mark up for retailers is 100%.
We started out with our design, printed a prototype and then a little bit of test fitting. We found a reasonable amount of clearance with the OEM intake. The picture below is using our final machined component.
Lets take a look at the thermostatic valve that we ended up using. We purchased a few of these from several companies, as we wanted to test the operation temperature and when the valves actually started to open. A valve that is functioning correctly will open at its set point or about 5 degrees from it. A 185 degree valve should open at 180 degrees to 190 degrees Fahrenheit. The valves we purchased were from a European manufacturer and an “over-seas” manufacturer . Our testing thermostatic plate is a little dirty as we cycled it more times than I would specifically count. We did find a few interesting conclusions.
The 2 valves manufactured in Europe both opened in the correct range and cycled with no operational issues opening between 179 F and 184 F. Fully closed at around 190 F.
The 3 valves manufactured “over-seas” had several issues. The 3 valves were rated at 160F, 185F, and 200 F. However none of these valves opened at the correct operational temperatures. What’s even more worrisome is that all 3 leaked the wax from inside the thermostatic valves leaving a residue on our thermostatic plate. If this was actually used in a vehicle you would now have wax in your oil system.
In short, we chose to go with the European manufacturer. Why is it important to have correct operating ranges? If a thermostat opens too soon, your oil temperatures will take longer to warm up as you will be cooling your oil as it’s also attempting to reach its operating temperature. If a thermostat does not open at the correct operational temperature, then it’s acting like a normal oil system and the point of your oil cooler system becomes pointless.
The valves we used for testing are shown below.
We also considered the the amount of material for the aluminum thermostatic plate, and thought that the difference could affect the valve opening times due to heat transfer rates. Our conclusion from this testing was negligible with both adapter plates opening within 1 degree of each other after several testing cycles.
Here are a few pictures of our finished kit, we will be offering it standard in raw aluminum and anodized black.