Project S2000 – Part 9 – Oil Cooling

Project S2000 – Oil Cooling

by Khiem Dinh

Khiem Dinh is an engineer for Honeywell Turbo Technologies at the time of this writing.  All statements and opinions expressed by Khiem Dinh are solely those of Khiem Dinh and not reflective of Honeywell Turbo Technologies.

Tracking the S2000 and monitoring the oil temperatures has taught us one thing: it runs hot!  Even with the reduced coolant temperatures afforded by the Koyo radiator, the oil temperatures were still too high for a car to be tracked for long-term reliability.  This is occurring at completely stock power levels even (the more power an engine makes, the more heat it makes and consequently needs to reject).  High oil temperatures lead to reduced oil viscosity and faster oil breakdown.  Low oil viscosity can mean inadequate oil film strength and thickness with the end result being metal-on-metal contact between engine components.  While low oil viscosity may not grenade your engine immediately, it will lead to accelerated wear of components.

I tried a band-aid approach of using high viscosity oil (15w-50) relative to the recommended fill (10w-30) for my track day in the summer heat of the desert.  This approach may solve the oil viscosity and pressure issue, but does not address the issue of oil breakdown with excessive temperatures.  Also, rod and engine bearings are made of relatively soft metals that don’t take well to being heated to high temperatures.  Lastly, high oil temperatures mean a hotter running engine leading to a higher propensity for detonation.

I decided on an Earl’s Temp-A-Cure oil cooler.  This line of coolers was designed for the typical air speeds and oil flows seen in automotive use.  They’re made of high grade aluminum and are furnace brazed to create the most thermally efficient joint possible between the tubes and fins.  Earl’s choice of fin density was selected to maximize heat transfer to the outside air.  I’m using a 34 row cooler with a 10.5″ height and 13″ width.  I also opted for the optional mounting bracket kit.  My old roomie left behind a roll of rubber that had adhesive on one side.  I applied the rubber strips to the surfaces that would come in contact with other objects when mounted.

The S2000 engine, along with other high performance engines, uses piston oil squirters.  The purpose of the piston oil squirter is to spray oil at the back side of the piston and reduce the temperature of the piston.  A cooler piston reduces the likely-hood of detonation.  Spraying cooler oil at the piston is obviously better than spraying hotter oil at the piston.

So we can see that the benefits of running oil at its proper operating temperature are multifaceted.  Doing so will extended the service life of the oil, reduce engine wear, and reduce the likelihood of detonation.  Now the challenge was to figure out an oil cooler setup for the S2000 that fulfilled the role of both a daily driver and track day vehicle.

Earl’s -12AN Auto-Fit Ano-Tuff fittings use a military spec hard anodized coating for corrosion resistance and toughness.  The fittings were paired with Pro-Lite 350 hose.  When assembling the fittings to the hoses, remember to use either some motor oil or Earl’s assembly lube.  Installing the fittings onto the hose was a snap.