Often one could be either scared or mesmerized by what is a 911 Engine. Actually, they are very reasonable and efficient in layout in design, almost so much so, it is what some might describe at the basics of an engine used in airplanes. The 911 engine is a six-cylinder engine with the crankcase vertically split along an axis that runs front to rear. The cylinder layout lays flat and opposed with eight main bearings.
The forged steel “tenifer” crank shaft turns as the engine is in momentum smoothly throwing six rods that are spaced in such a way to fire one cylinder at every 120 deg intervals. Directly under the spinning crankshaft, complete with by-pass oil holes is what acts as a counter rotating shaft or “layshaft” is driven by crankshaft gears. The layshaft then also has a pair of drive sprockets for camshaft chains. There is an odd ratio of 28 teeth on the crankshaft and 48 teeth on the driven layshaft gear requiring nine crankshaft revolutions before having the cycle repeat itself. During those cycles the engine takes advantage of also gearing drives for the dry sump oil system’s tandem scavenge and pressure pumps, with yet other crankshaft gears that run 1/2 speeds. These other gears is what then can be traced to run the distributor.
Mounted on the engines are casted Pistons and aluminum cooling finned cylinders (Biral) are 6 identical cylinder heads. The heads then have combustion chambers that are near-hemispherical, with one intake valve that when open, closes the exhaust valve. Just set at an angle of 59 degrees, these slanted from vertical valves for the time would result in a very efficient and genius physics of operation directing power where it exactly needs to be. If you think about it .. it was rather unusual for the time, but stayed the as the main design ideas for all 911 since then.