I should also add that rolling coal normally, as in - half burned fuel coming out the exhaust valves, is a reliable way to make lots of black smoke but EGTs are not the only concern.
What you are doing at that point is washing down your piston rings and contaminating your engine oil. There is no way to measure the quality of the lubricant in your engine other than via sample testing. So you could be causing premature wear on your rings, bearings and possibly even lifters without knowing it. Half burned fuel will result in carbon build up that can clog the rings enough that they no longer press against the cylinder wall correctly, and again gasses are allowed to flow more freely from combustion side to crank case side.
One of the big advantages of the indirect injection method is the fuel starts burning before it even sees the piston or the wall of the cylinder (very close to the compression rings). Even direct injected diesels have a deep dish in the center of the piston for combustion to start, and spread out from there. In either case, the ideal senario is for combustion to be complete before any gasses reach the cylinder wall. If you have half burned fuel in that mix of gasses, it WILL reach your piston rings and start things rolling in that direction.