21. In the Otto cycle , there is no heat transfer during the process 1 2 and 3 4 as they are isentropic processes. 22. In Otto cycle engines, the cooling effects of water injection also enables greater compression ratios by reducing engine knocking ( detonation ). 23. The Otto cycle consists of isentropic compression, heat addition at constant volume, isentropic expansion, and rejection of heat at constant volume. 24. It was a low-RPM machine, and only fired every other stroke due to the Otto cycle , also designed by Otto. 25. The absence of any compression process in the design leads to lower thermal efficiency than the more well known Otto cycle and Diesel cycle. 26. The Otto cycle design convention calls for combustion just before top dead center ( BTDC ) in order to allow combustion pressure to build. 27. Comparing the two formulae it can be seen that for a given compression ratio ( ), the ideal Otto cycle will be more efficient. 28. Other cycles, such as the Otto cycle , Diesel cycle and Brayton cycle, can be analyzed from the standpoint of the Carnot cycle. 29. The heat energy source is generated external to the Stirling engine rather than by internal combustion as with the Otto cycle or Diesel cycle engines. 30. It is this engine ( the Otto Silent Engine ), and not the Otto & Langen engine, to which the Otto cycle refers.
