If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the %age increase in efficiency will be________________? August 16, 2021January 27, 2019 by admin If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the %age increase in efficiency will be________________? A. 2% B. 4% C. 8%D. 14% E. 27%.