piston engine thermal efficeincy.
Hi
just a couple of questions about piston engine theory.
as far as i remember the cubic inch displacement determines together with the volume of the combustion chamber the compression ratio referred to the ratio of the volume in the cylinder when the piston is at the BDC to the volume in the cylinder when the piston is at the TDC.
The compression ratio, limited by the engine strength and by the number of octane in the fuel providing an indication of the fuel to resist detonation when ignited, determines both the thermal efficiency and the volumetric efficiency.
The thermal efficiency of an engine represents the ratio of the chemical energy stored in the fuel burnt to the work produced or in other words the ratio of the heat energy of the fuel to the work produced by the pressure acting upon the piston head.
Does the compression ratio affect the thermal efficiency by increasing the D variable in the Work formula W=F D and thus the work or there is something more to it? cos as far as i have understood the compression ratio provides merely an indication of how far the piston can travel, while i am having an hard time relating it to the pressure increase within the cylinder barrel - although i do understand that the higher up the TDC the more the fuel air mixture is squeezed.
Anybody can shed some light?
One more question: do manufacturers provide an indication of the thermal efficiency of each engine, or does it varies based on power setting? and if so what is the thermal efficeincy of the Lycoming IO360 vs the Lycoming 360?
Finally, does the Lycoming IO 360 mounted on the 172SP have a flywheel?
Many Thanks and Merry Xmas
baobab72