Crankcase

Crankcase

The new 911 models feature a two-part, vertically split crankcase with an integrated crankshaft thrust block. The advantage of this design is that smaller components can be used, while the separate bearing saddle with cast-in cast iron elements is no longer needed, thereby reducing the overall weight of the engine.







The actual crankcase on the new 911 engines is made completely of an aluminum-silicon alloy (ALUSIL).

This procedure 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 therefore 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 sleeves.

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 crankcase cast parts.







Cylinders are now connected differently in the cylinder-head cover area. 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 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 reducing fuel consumption. Even piston and piston-ring sealing has been improved as a result of the higher retention of roundness of the cylinders. The entry of oil from the crankcase into the combustion chambers and the entry of the fuel-air mixture from the combustion chambers into the crankcase is reduced. This both improves consumption and reduces performance-inhibiting overpressure caused by blow-by in the crankcase.