Turbulence plays a very important role in combustion as the flame speed is directly proportional to the turbulence of the mixture.. This is because, the turbulence increases heat transfer rates leading to higher combustion. Insufficient turbulence provides low flame velocity, incomplete combustion and reduces the power output, increases the unburnt carbon products thus increasing the NO,CO etc. resulting in high pollutant exhausts. Rate of flame propagation affects the combustion process in SI engines. Higher combustion efficiency and fuel economy can be achieved by higher flame propagation velocities. This book presents the attempt made to enhance the turbulence inside the cylinder by injecting solid nanoparticles into the air fuel mixture.