some cylinder head history and personalities new to me

https://www.msn.com/en-us/autos/enthusiasts/four-valves-per-cylinder-part-3/ar-AAZCIIY

sample 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.

end quote

beginning of series

https://www.cycleworld.com/story/blogs/ask-kevin/four-valve-motorcycle-engine-design-explained/

Did you hear about the Polish terrorist who tried to blow up a bus?




















Burned his lips on the tailpipe.....

Dang it,
I like that joke
but the Polish keep on proving
they are far from “slow”

Polish codebreakers
Polish Spitfire pilots
etc

1 foot per second??? Whoever made that statement never threw a cup of gasoline on a fire... I promise you it travels much faster than that.

https://www.youtube.com/watch?v=Hi7tZVV-o8A

Notice the flame first enters the field of view at the 45 second mark and by the 47 second mark has covered at least 20 feet and looks like more than that honestly and this is not exactly an ideal AF mix.

We need to be careful as to whether we are comparing “apples to apples”.

Still air speed is not like throwing a liquid fuel toward a “crackling” fire.

In mining school it is common to show a film where 5% methane in still air burns sluggishly
10% methane “explodes”
and 20% methane burns sluggishly again.

It is hard to believe
but in my great-great grandfathers time
each mine had a “Fireboss”
whose highly paid job was to go in and burn off the methane ( aka fire dampf) in the tunnels.

Near Newcastle a mine manager went out of his way to take me to a huge fire bricked chimney room in a very old coal mine where instead of using a propellor fan (not yet invented yet) a huge fire was always going to “induce a draft of air” through the tunnels. The manager told me when the methane emission was high the fire burned without any coal. The flames did not spread back into the tunnels because of copper “quench curtains.”

Here is a scientific report about flame speed in still air.
1 foot per second would be about 32 cm per second.
Scroll down to the graph
“Laminar Flame Speed cm/sec on the left axis
and “Equivalence Ratio” on the right axis.

https://www.sciencedirect.com/topics/engineering/laminar-flame

This statement right here negates the theory proposed.

By 1960, two-valve engines had been highly developed

Somewhat developed, maybe. A bunch of improvements were right around the corner by in 1960 no.