For an engine operating on air standard Otto cycle, the

For an engine operating on air standard Otto cycle, the clearance volume is 10% of the swept volume. The specific heat ratio of air is 1.4. The air standard cycle efficiency is-

V_c = clearance volume = 10% of swept volume
∴ V_c = 10% V_s = 0.1 V_s

Now r = compression ratio =	V_c + V_s	≈	V₁
	V_c		V_c

=	(0.1V_s + V_s)
	0.1V_s

=	(1.1)V_s	= 11
	(0.1)V_s

Now standard cycle efficiency, η = 1 -	1
	r^{γ - 1}

η = 1 -	1	= 61.7%
	(11)^{1.4 - 1}