Keeping the oil cool (total cost £425, including gauges)
This mod will work for all M52, M54 and M56 engines. Roadsports races last 45 minutes but the club enduro races are 2 hours. Others report that at close to 45 minutes the without an oil cooler the temperature gets uncomfortingly high. This presents a serious problem as the oil temperatures will steadily rise further and could exceed the design perimeters of the oil, typically 160 degrees. It can be compensated somewhat by using a heavier oil 10w60 instead of 5w40. The heavier oil helps maintain the oil pressure, and therefore protection, as the oil heats and thins.
(picture courtesy of bimmer world)
A much better solution is to fit an oil cooler. There are generally two schools of thought. The first, and more conventional approach, is to fit the oil filter housing of the S50B30 e36 M3 (pictured above). To fit it you’ll need to remove the air box, the alternator and aux drive belt, along with the old filter housing. The M3 housing incorporates a thermostat and has M12 tap off points specifically to run an oil cooler. It’s expensive (used £275+), and has the downside of another component to fail i.e. the internal thermostat, and lose the cooling effect if it failed to open during a race.
Using the KISS (keep it simple, stupid) principle I decided that I didn’t want a thermostat that could fail. I wanted a simple design that would tap off the existing oil filter housing and work all the time. I’d just cover the oil cooler when in use on the road. Enter the second method, the oil filter tap off.
(picture courtesy of PMC Motorsport)
There are a few on the market but I settled on the PMC Motorsports housing as it incorporates two 1/8 npt sensor points. It’s also available from PO Performance in the UK, they shipped fast and it was actually cheaper than buying direct! The fittings are AN10. The 1/8 npt points can be used to add separate oil pressure and temperature gauges as well as an independent oil pressure switch which would flash warning lights within the CARTEK shift lights. I ended up using 52mm Simoni Racing gauges for the oil temperature and pressure as they included the sender units. Gauges can be expensive if you have to buy separate sender units. The third sensor is fitted to drive a low pressure warning through the CARTEK shift lights (see video below).
The gauge surrounds in the air vents were supplied off eBay.
Oil cooling is provided by a MOCAL (the industry standard) 235mm 19 row oil cooler. I managed to get a used one off eBay for £50. It also had AN10 (or 10JIC) fittings. You can get a new one from Merlin Motorsport currently for £139.
9ft of braided hose and AN10 fittings completes the kit.
Oil Cooler Mod, (total £425)
- £57 (M) used (eBay) Mocal 235mm, 19 row cooler
- £39 (M) Susa ProLine Mounting brackets (suits MoCal)
- £134 (M) BMW M52, M54 & M56 oil filter cap adapter for oil cooler.
- £94 (M) Digital 52mm Gauges for Oil Pressure and Temperature (including sensors.)
- £24 (M) 20 psi oil pressure switch of driving Cartek shift light warning system.
- £40 (M) 2x 52mm mounting grills for mounting gauges in top air vents.
- £37 (M) AN10 Stainless braided oil line 9ft.