Naming

Nevertheless, one thing was changed times to times: the name. From Type 901 (in order to coincide with the car’s name, although the latter was eventually changed to 911 under the protest from Peugeot) to Type 911, 930, then renamed to M30 briefly for the turbo, and at last M64. It is generally regarded that the M30 did not worth a new name because it was actually a revised Type 930 Turbo 3.3. In contrast, the M64 had the most changes.

The original engine, Type 901/01 was deemed to be an advanced and highly specified engine for a production car. Its good elements included:
 

Aluminium head and crankcase; Biral cylinders, i.e., cast iron cylinder liner with aluminium fins casting around; Cast aluminium pistons; Hollow, sodium-filled exhaust valve for better cooling; Forged steel crankshaft; 7 main bearings for fully counterweighted crankshaft; Hydraulic timing chain for valve gears.

 

The trend of evolution

During the 3 and a half decades, the Type 901 engine faced challenges times to times from tightening emission / noise regulations as well as the weight increment. The ask for cleaner emission and more flexibility (thus torque) without any trade-off in performance, cost and reliability guided the development of the engine. Porsche met the demand by increasing engine displacement times to times, plus some other latest development (some were learned from racing program), such as forged pistons, Nikasil treatment, turbocharging, intercooler, electronic fuel injection / ignition, advanced engine management program, variable intake system, twin ignition, low back-pressure exhaust .... the 901 engine and its evolutions met the goals yet achieved considerable improvement in performance.