some cylinder head history and personalities new to me
https://www.msn.com/en-us/autos/enthusiasts/four-valves-per-cylinder-part-3/ar-AAZCIIYsample quote
Squish, Turbulence, and Combustion Speed
A chemically correct mixture of perfectly still air and fuel has a combustion speed in the order of 1 foot per second—too slow to make the spark-ignited internal combustion engine workable. Fortunately, turbulent charge motion naturally accelerates combustion, shredding and rapidly distributing the flame kernel originating at the spark plug’s gap. The source of this turbulence is the persistence of the fresh charge’s high-speed flow, entering the cylinder on the intake stroke. Achieving fast combustion depends upon not letting this high-speed flow decay rapidly from contact with obstructions such as a tall piston dome or other features of the piston crown.
As the piston nears TDC and the ignition spark occurs, rapid charge motion transforms into small-scale turbulence that very effectively increases the surface area of combustion.
By 1960, two-valve engines had been highly developed, and benefited from fairly rapid combustion accelerated by deliberate axial swirl of the incoming fresh charge. This swirl came about by offsetting the intake port, making its flow enter the cylinder on a tangent. Extra combustion speed was gained by the Polish engineer Leo Kuzmicki at Norton (though he had been a flight engineer and had lectured at university, up to 1950 he had been sweeping floors at Norton) in the form of piston-to-head “squish.” As an area of piston crown closely approaches a corresponding area of cylinder head at TDC on the compression stroke, the charge between them is forcibly ejected at high speed, giving the whole charge a last-moment stir. The faster combustion occurs, the less time there is for heat loss from the hot combustion gas to the piston crown and cylinder head, and the greater the fraction of power from that gas that reaches the crankshaft.
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beginning of series
https://www.cycleworld.com/story/blogs/ask-kevin/four-valve-motorcycle-engine-design-explained/
