"Something else to think about in the scenario that the waste spark is igniting anything at the top of the exhaust stroke. Let's say the a/f mixture went through the ignition cycle without lighting off. Now the piston drops and uncompresses the mixture.
When this occurs, isn't some of the heat from the previous compression now drawn out from the decompression?
When an a/f mixture is decompressed, does some of the mixture condense into larger droplets from the previous vaporized state, due to the drop in pressure and temperature?
Isn't most of the charge expelled from the cylinder way before the 24 or so degrees before TDC of the exhaust stroke? In fact, most likely past the turbo by this point with a short runner exhaust system?"
Don,
What I think you maybe missing in regards to left over exhaust to ignite, is the overlap , especially with bigger duration cams. The new fresh charge being pumped into the chamber during this overlap, some of it goes out with the exhaust. Cant help it. Lobe separation angle also plays a part here. When this happens I can see why it may raise EGT's. There may be enough fresh A/F to burn.
