Quote:
Originally Posted by racprops
You getting close, Consider this: Gas burns SO SLOWLY that they have to start it burning some 30 degrees (or More) BEFORE top dead center...and as even the finest droplets are NOT vapor but converting TO vapor only 30% is able to produce the power stroke, the rest do burn but make no power as they are still burning though the rest of the rotation of the crank and the final piston moving though bottom dead center and back up in the exhaust stroke and still are burning on its way out of the exhaust valve and out the exhaust manifold and tail pipe, which is IF you were running straight pipe a like a dragster you see flames.
The power stroke is some 10 degrees after top dead center and down to about 70/80 degrees to bottom dead center, after bottom dead center that burning fuel is a waste of fuel as it can make no power..do no work.
IF you are running vapor you then need timing of ZERO DEGREES or a couple of degrees AFTER top dead center because vapor explodes so nearly 100% can produce the power stroke and THAT means all of the 20 to30% of the fuel makes more power with no waste and give more power an more MPG.
It is used up during just the few degrees of crank turning after top dead center and can be all gone before bottom dead center, and there is no (or very little) waste of fuel.
At least that is the theory... as I under stand it.
Knocking is when fuel burns or explodes BEFORE top dead center...
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correction:
when the piston is at 12 past Top dead center it is moving faster than the speed of the burning fuel typically engines have 3 to 7 milliseconds when a fuel explosion will actually be pushing on the piston. Issue is it the time it takes for the liquid gas to turn into vapor mix with oxygen and then burn in a secondary explosion. the time can exceed 50 milliseconds. in most vehicles the exhaust valves open in about 7 milliseconds. this means you'd be burning up your exhaust valves. the combustion must be absolutely stopped by 25 past Top dead center to prevent valves from burning