Crankcase

Crankcase

The new Boxster and Cayman engines, like the 911 models, feature a two-part, vertically split crankcase with integrated crankshaft thrust blocks.







The actual crankcase is made completely of an aluminum-silicon alloy (ALUSIL).

This method offers the following advantages:

- With ALUSIL, the crankcase can be made from one cast, without cylinder sleeves and without having to coat the cylinder bores afterwards.
- ALUSIL is an excellent heat conductor and thus allows high specific engine output values.
- ALUSIL has excellent friction properties. Since the pistons and piston rings slide on the exposed silicon crystals, they have a low tendency to seize.
- ALUSIL does not present any recycling problems because the crankcase does not include any foreign materials, e.g. cast-in cast iron cylinder liners.

The listed advantages of the alloy are certainly important arguments in its favor. Indeed, the low-pressure chill-casting procedure, which has since proved to be the best solution by far for casting ALUSIL, is an important prerequisite for reliable, mass-produced cast crankcase parts.







Cylinders are now connected differently in the cylinder-head cover area, as on the 911 models. The individual cylinders, which originally stood freely in the water jacket (open deck design), are now connected by a closed cylinder deck (closed deck design). The advantage of this design is high cylinder stability, particularly with regard to the cylinder shape (roundness and low cylinder deformation) over a wide load and temperature range. This has the added advantage of reducing friction and thus lowering fuel consumption. Even piston and piston-ring sealing has been improved as a result of the enhanced retention of roundness of the cylinders, which means a reduction in the blow-by gases that can flow into the crankcase during combustion. Conversely, the entry of oil from the crankcase into the combustion chamber is reduced, thus also lowering oil consumption.