555 Engineering GR Corolla Engine Oil Cooler Development

2 มิถุนายน 2024

An outline of the product development and testing of the 555 Engineering GRC Engine Oil Cooler.

Component Choice and Design Considerations.

555 Engineering chose Setrab Oil Components because of their experience with motorsport and the fact that all of their coolers have posted thermal duties and expected pressure losses.

The main design criteria were:

Thermal Performance

Targeting the 300 - 400hp thermal output range. Because this is an off the shelf kit, it has to accommodate a large range of use cases from cold weather use in Denver to summer use in Arizona.
Choosing a cooler that is too large could result in overcooling. The approach is to size the cooler correctly and then use airflow to meter for the extreme use cases at either end.

Oil Pressure Loss Mitigation

Use a quality single pass exchanger vs a dual pass exchanger to stay as close to factory intended pressures as possible.
Use low pressure loss bends and fittings (ie no banjo fittings) while maintaining ground clearance.

Packaging (Air Curtain Area)

The front grille area does not easily support a cost effective single pass cooler with a surface area large enough that wouldn't heat soak.
We figured everyone will try to fit the largest refrigerator sized intercooler for the front area. This area does not impact that packaging.
Does not impact factory heat exchange stack (intercooler, radiator, AC condenser).
There's a system level factor that will be revealed at a later date.

Initial Testing

Initial testing was done with angling the back of the heat exchanger core to where the factory heat exchangers (intercooler, radiator, AC condensor) vent to and using a replacement air curtain inlet to deflect air onto the core.

Bottom view facing up

Inlet Deflector Configuration; Road Testing

555 Engineering conducted road testing for initial baseline pressure and temperature comparison.

Initial pressure testing was done same day lead / follow with a baseline and test car. This data lacked a lot of high rpm data but it was a good baseline to set expectations.

Road testing was followed by a series of Track tests conducted at Thunderhill Raceway. A few different air inlet configurations were tested including a 3D printed air deflector and a cut factory inlet.

Inlet Deflector Configuration; Track Data Analysis

The oil pressure curve was great. There were a few pressure drops noted in stock and modified data logs that didn't influence the curve above. This will be covered in a separate writeup. But for the purposes of testing this Oil Cooler kit - pressure telemetry was great.

Temperature reductions in this configuration group were OK (average 15F reductions from a previous track event). But we felt like we were losing thermal duty potential due to the open nature of the air deflector. It was decided after this test to add ducting that would seal the oil core to the front bumper.

Ducting Addition

The intent here was to add a diffusion duct from the air inlet to the core and create a pressure effect over the cooler core that would increase heat transfer. This is the configuration that made it to the production kit.

Credit to The Fast and The Nerdy for this visual

One of our customers, Marcus shared some really nice video telemetry with us and also fortunately had telemetry before installing his 555 Engine Oil Cooler which makes for a nice comparison.

The cooled data below is from a configuration with ducting using a stock inlet that is modified with a single cut to open the inlet opening. Temperature reductions of -30F were realized despite the ambient temperature being 25F hotter from the stock dataset.

More Inlet Testing

To maximize the inlet opening for the 555 Engine Oil Cooler a mesh inlet was designed to achieve a few things:

Further maximize airflow over just cutting the factory inlet
Provide a no cutting option for the kit installation

Testing was done with a baseline car running a 555 Engineering Oil Cooler initially running a stock uncut air inlet. Even with the relatively small stock inlet opening temperature reductions around 15F were measured on average. Despite the small size, once the vehicle gets up to speed the inlet still provides some heat transfer.

Baseline car (stock inlet) left; 555 Dev Car (Mesh Inlet) right

A test comparing the stock inlet vs mesh inlet were done. Then a test comparing the cut inlet vs mesh inlet were done.

Average temperature reduction of the mesh inlet over the stock inlet was 16 °F.

Track update to above testing. Another test at Sonoma Raceway was run showing the airflow difference with a full open mesh inlet indicating heatsoak from less airflow.

Inlet configurations below:

Stock Inlet

Cut Inlet

To clean up the cut line, we now ship kits with edge trim to give a more OEM look. More can be seen in the Oil Cooler instructions on the product page.