Such variables characterizing {HEAD ~ the combustion} in {TAIL ~ the combustion chamber} are already recorded in modern internal combustion engines 
in
Such variables characterizing { HEAD ~ the combustion } in { TAIL ~ the combustion chamber } are already recorded in modern internal combustion engines
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH