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Discussion Starter · #1 · (Edited)
QUENCH, the distance between the cylinder head and the pistons flat area in the combustion chamber

run less than about .035 thousands and at high rpm levels the pistons might hit the cylinder heads, run more than about .044 thousands the QUENCH effect of forceing the fuel air mix to the center of the cylinder from the cylinders edge area looses both speed and effectiveness, remember the quench area must be so tight that virtually all the fuel/air mix is forced into the center area and none is allowed to burn untill its squirted into the burn area increaseing turbulance and burn efficiency
in theory the much better quench, combined with the shorter more compact area the flame front needs to cover and the far higher turbulance combine to allow more of the pressure to build AFTER the crank passes TDC on the end of compression and begining of the power stroke

its mostly an advantage in that you get a more even burn in the cylinder and less chance of detonation.
look, it takes approximately 40 thousands of a second for the flame from the ignition to cross a 4.25" bore,at low rpms and still takes about 15 milliseconds at high RPM due to the much faster movement of the compressed fuel air mix in the cylinders, lets look at what that means
if the chevy plug is located 4/5ths of the way to one side thats a time of about 32 thousands for the pressure to build as the flame travels 3.4" in the chevy but in a compact combustion chamber it could only take the cylinder flame front less than 10-20 thousands of a second to travel acrossed the combustion chamber for a complete burn at low rpms, this of course speeds up as the swirl and turbulance increase with increased engine RPMs but the ratios stay similar. this results in more useable energy WORKING on the piston AFTER IT PASSES TOP DEAD CENTER ON THE POWER STROKE. BUT MODERN WEDGE combustion chambers use increased QUENCH to speed the flame front and lower the burn time combined with a smaller combustion chambers look at this chart

keep in mind that the cylinder pressure starts, builds to a peak and drops off all before the piston moves more than about 1/2 inch away from TDC and that if your wasteing 10-20 degrees of rotation compressing the burning mix in a slow to ignite combustion chamber your wasteing engine power


things to read


you only have QUENCH if theres a flat area on the piston that mates to a matching flat area on the combustion chamber roof, on these pistons dual quench areas throw the compressed fuel/air mix to the center from the twin quench areas
notice, if used with this head, that only one side would have a fairly large and EFFECTIVE QUENCH area ,(the side away from the spark plug)
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