What is the difference between scavenging and supercharging ?

Ans 1 : Scavenging is process of flushing out burnt gases from engine cylinder by introducing fresh air in the cylinder before exhaust stroke ends. Supercharging is the process of supplying higher mass of air by compressing the atmospheric air.

Ans 2 :

• A supercharger is a device used for forced injection. The “forced injection” in which the external pressure is applied to the air to inject it to cylinder. This helps the car to boost up its power as more fuel can be added.
• Superchargers increase intake by compressing air above atmospheric pressure, without creating a vacuum. This forces more air into the engine, providing a “boost”. But for forcing the air into the cylinder, the supercharger must acquire power by some means, and so it does by the rotation of the crankshaft. The part of energy of the crankshaft is used up by the supercharger for its work and there is a net loss of total energy of the fuel.
• But supercharger can add up to 46% of total horsepower and 31% of torque. They spin at high rpm of 50,000 to 65,000 rpm

mechanical engineering interview questions

mechanical engineering questions