Oil Circuit

Oil cooling requirements for the 964 engine exceed that provided by the trombone loop in the front fender. The 964 engine has no engine mounted oil cooler or thermostat, and relies on external elements to do these jobs. A Carrera front fender cooler with fan was already in place on the SC, and this cooler alone was used for a test period, but the cooling provided was considered marginal. An additional cooler was installed, mounted under the front bumper, and plumbed in series with the Carrera cooler. The Carrera cooler alone routinely allowed temperatures to hover around 230 degrees, and the second cooler reduces temperatures by 20 - 30 degrees.

The oil lines to the scavenge connection on the left side of the engine, and to the gravity feed connection on the right side of the engine, must be replaced in order to be compatible with the SC oil tank and front thermostat. The 964 scavenge line is replaced with ones from the early 2.7 liter (part #s 911.107.739.10 and 930.107.729.10), and a tube is fabricated for the gravity feed (right) side of the engine which matches the size and function of the lower tube of the stock 3.0 liter engine oil cooler. For the right hand side engine oil line, a tube was constructed from the proper size screw-on oil fitting and an approximately 11" steel thin wall tube matching the diameter of the 3.0 liter oil cooler tube, and these two joined by welding. This arrangement allows use of the stock "S" shaped SC oil line to the right side of the engine from the SC oil tank if using the SSI exchangers. If the B&B headers are used, this rubber hose is replaced by a welded-up steel tube (provided by B&B) which is required due to the close fit of the right side header to this line.

Engine breather lines to the SC oil tank were fabricated from the stock lines supplied with the 964 engine. The line from the top engine boot to the top connection on the oil tank, needs an additional 90 degree turn fitting in order to turn the breather line toward the front of the car to pass beside the air flow sensor. In the C2, this line normally passes over the air flow sensor, but there isn't enough clearance in the top of the SC engine compartment. The small vacuum line which went to the former C2 oil tank is plugged at the engine manifold.

The breather line to the oil tank from the engine air flow sensor boot should be fitted with a restrictor inside the line. The size of this restrictor should be about 1/8". If a restrictor is not used, the engine will die when the oil tank filler cap is removed to check oil level.

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