Sorry for interrupting the actual discussion, but I wanted to add my two cents here. I calculate squish height at the applicated engine speed range and engine temperature, means elongation of the crank drive due to thermal expansion and by acceleration. On a 86 mm stroke one should consider 0.55 mm@10,000 rpm and WOT temperature setup within a NA application. That means on a cold squish height of 1.0 mm there are only about 0.45 mm left, and what was designed to 20 m/s cold get about to 35 m/s peak squish velocity on a typical 4-valve head of a square bore-stroke engine design.
That works well and is still under the by G.P. Blair recommended peak squish velocity of 25 m/s (cold condition), which would be reached at 0.7 mm cold. But heated, this would relate at 10,000 rpm to a squish peak velocity of 49 m/s. Which is way to high and will increase knock likeliness. Why?
The radial velocity of the mixture is still profitable for combustion, but the risk introduced by both, the increased turbulent kinetic energy level triggers chemical reactions as the distance to activation energy is lowered and therefore the likelihood of a spontaneous oxidation happens as well as the kinetic pressure at squish geometry reduces the static pressure there, creating a force for the liner wall and fireland accumulated oil to be sucked into the combustion zone, causing oil droplet induced knock.
Squish induced increase of turbulent kinetic energy (TKE) is a great supporter for a fast and efficient combustion in the combustion main zone (but bad for emission), which is for 4-valves head a favorable solution. But going to far will cost engine safety and power if parameters against it are not well chosen. A swirl induced increase of TKE is a much smarter way, especially if combined with a bit weaker squish as mixture homogenization, emission and combustion duration will get improved. But as everything is a compromise, especially when it reduces VE, a compromise has to be found.
Thence, there are no recommendable squish heights in general, a better design parameter would be the squish velocity at applicated engine speed range and temperature. Of course that need some math skills to model the squish velocity correctly. Therefore a thumb rule for a collection of rod length, specific materials, bearing clearances, oil weights, stroke heights, gasket seating heights and part weights may work fine, but finally, and because testing is expensive, a dedicated calculation model is the key into the pretty complex task of getting into the optimal squish height.
Things get may get less complex once combustion effects get reduced as delay times are to big. Beyond 9000 rpm the TKE threshold to create instantaneous knock get quite high just because the self ignition delay is big enough to fail to knock, once mixture temperature at BDC is well below 40 °C, which is quite challenging. Just think of a combustion event at 10,000 rpm, which should be no longer as 0.7 ms, that means average combustion speed should be 61 m/s, which is well over 200 times of the laminar flame speed of a lambda = 1 gasoline-air-mixture combustion. Thence it is quite possible to see a well advanced ignition timing beyond 9000 rpm while the piston hit the head without any squish induced knock. Slower rotating engines are sometimes more complex
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I saw oil induced pre-ignition caused by to big squish velocities causing pressure gradients of 13 bar/°ca, which did their thing on the engine, nothing funny on almost 4000 hp engine at almost 100 psi of boost at a full-sized equipped engine test stand.