per minute of the engine the resulting graph may be linear in nature one purpose of the supercharger 68 and turbocharger 67 is to sustain the air pressure in the forced charge air system 200 by replenishing the amount of air in the fill tank the pressure of the flow of air available for scavenging or entering the combustion chambers is equal to combination of the pressure for the air exhausted from the chambers air supplied as cooling air through the flywheel 5 and the air flowing in the exhaust ducting 66 that leads to the turborcharger 67 the amount of air flowing to the turbocharger 67 can limit the efficiency of the turbocharger 67 thereby requiring supplemental air arising from the use of a supercharger 68 a supercharger 68 will supplement or supply an additional air volume pressure to the fill tank the exhaust of air from the engine 1 through the exhaust ducting 66 and turbocharger 67 supercharger 68 arrangement may be cooled through the use of a radiator 71 prior to being re circulated for use as supply air for the engine assembly 1 another aspect of the present disclosure is to provide a method of operating an internal combustion engine assembly as described above the method generally comprises providing an engine assembly having a plurality of combustion chambers each combustion chamber is delimited by.