Installing an external oil cooler

[wkrtsm]

About 17 years ago, the rubber seals of the OEM tower oil cooler that sat in the fan shroud were leaking, so I replaced it with a cheap Brazilian knock-off, that also started leaking.

An image of the stock OEM cooler is shown below (on Pelican Parts):



Notice the large rubber seals in the image above, which sit directly on the hot engine casing!

After this, I covered up the cooler mount holes in the case with a by-pass plate from 356 Enterprises. The by-pass plate does not use the same large rubber seals as the OEM tower, but rather gaskets which are more like the generator stand gasket or oil filler head gasket (image below):



I then installed an external cooler (Mocal 235mm/Series 6 Oil Cooler model with M22 x 1.5 female ports) from British American Transfer (BAT).

(if you click on the buttons at the bottom of the BAT web page, a pdf product description/catalog will unknowingly be download to your Downloads folder – I purchased a 235 matrix HD cooler with 19 rows -- Part #: 19 ROW A19F225HD).

The main tubing routes are shown in the pic below below with the 180F thermostat (from BAT), and oil filter mount from Empi. When the thermostat is closed, the oil goes directly to the filter and then returns to the engine. When the thermostat is open, oil routes through the cooler, then through the filter, and then returns to the engine. Either way, oil is always filtered.



The aluminum fittings are size "Army-Navy dash 10" (AN-10) with stainless steel braided hose (also AN-10), all made by Aeroquip, and available from Racer Parts Wholesale.

A close up of the DIY mounts I fabricated from steel stock (chromed) fastened to the engine mount cross-member is shown below:



Here's a better pic of how the DIY fabricated mounting brackets fasten to the engine mount cross-member:



Below is also a pic of the 180F Mocal thermostat:



The oil filter mount fastens to the engine mount cross-member as well



There are also 2 Spal cooling fans fastened onto the cooler which pull air in from the top to the bottom. They need to be wired to keyed positive (and ground). If you don’t know where to get a positive lead that’s live when the ignition key is turned on, the positive wire to the coil will suffice -- use a fuse or relay though. [I used this wire as the main cooling fan keyed positive, since with the new MSD, the old coil wires (pos, gnd) are no longer used].



Results: no more leaks inside the fan shroud on the engine casing. The surface area of the external cooler is about 2-3 times the OEM tower, so the oil is cooler. With the tower gone inside the fan shroud, more cooling air gets to cylinders 3&4 – which is also better. In terms of volume of oil, about a quart more is needed for the lines, filter, and cooler.

[wkrtsm]

In terms of oil, I now use Motul's (French) 300V 20W-60 Ester core racing oil, since the car is not a daily driver. Motul's ester core oils (300V line) are based on vegetable oil, have the greatest polarity for clinging to parts, reduce wear & friction, withstand extreme temperatures & pressure during racing, reduce consumption, and increase fuel efficiency. Regarding the vegetable oil issue, the "idea" is what happens to butter (e.g. fossil-based oils or synthetics with fossil base stock) vs. vegetable oil in a frying pan on high heat for 10 minutes -- this is the idea, but not precisely what happens (complicated). The esters will cling to parts better to reduce scarring during "cold" startups if I happen to drive only once a month. It's not cheap however, and cost me 34USD per 2 liter can from Amazon. I needed two 2 liter cans during the latest oil & filter change, so about 70USD per change.

Ester-based oils (like 300V) are used by F1, Indy, Team Porsche Racing etc., see example review here

An image of a 2 liter can of 300V is shown below: