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Effects of detonation  (1) Noise – As intensity of detonation increases, the sound intensity increases & it is harmful. (2) Mechanical damage – shock waves are so violent that it may cause mechanical damage like breaking of piston. It increases the rate of wear erosion of piston. (3) Pre-ignition – Due to local overheating of spark plug & this pre-ignition increases detonation. (4) Power output & efficiency decreases - Power output & thermal efficiency decreases due to abnormal combustion.

Absence of Venturi – No Restriction in Air Flow/Higher Vol. Eff./Torque/Power • Hot Spots for Preheating cold air eliminated / Denser air enters • Manifold Branch Pipes not concerned with Mixture Preparation • Better Acceleration Response • Fuel Atomization Generally Improved.

Supercharging: The power output of an engine depends upon the amount of air inducted in cylinder per unit time, the degree of utilization of this air and the thermal efficiency of the engine. The amount of air inducted per unit time can be increased by increasing the engine speed or by increasing the density of air at intake. As engine speed increases, the inertia load, engine friction, bearing load increases. The method of increasing the inlet air density is called as supercharging. It is usually employed to increase the power output of the engine.

Scavenging: At the end of expansion stroke the combustion chambers of a two stroke engine is left full of products of combustion. This is because unlike four stroke engines, there is no exhaust stroke available to clear the cylinder of burnt gases in two stroke engine the process of clearing the cylinder after the expansion stroke is called scavenging process. The scavenging systems are as follows : 1. Uniform scavenging system 2. Cross scavenging system 3. Loop or reverse scavenging system

Oil heaters:  When hydraulic circuit works in cold climate, then oil is solidifies below 5 o C temperature.  To liquefy the oil electrical heater or thermostatic heater are equipped with oil tank.  This increase the operating and maintenance cost of hydraulic system  The cost of hydraulic system is higher.  It heats the oil so that its viscosity increases and it can flow in the system smoothly.  Thermostatically controlled oil heater commonly used

It consists of a pump housing in which a pair of precisely machined meshing gears runs with minimal radial and axial clearance as shown in fig. One of the gears, called a driver, is driven by a prime mover. The driver drives another gear called a follower. As the teeth of the two gears separate, the fluid from the pump inlet gets trapped between the rotating gear cavities and pump housing. The trapped fluid is then carried around the periphery of the pump casing and delivered to outlet port.

We can generate very high pressures in hydraulic system. Due to this nature of hydraulic system we can use this power to lift, hold, press very heavy loads 2) Weight to power ratio of a hydraulic system is comparatively less than that of an Electro-Mechanical System. Electric motor weigh appropriately 8.5 Kg/kW whereas, same power hydraulic motor weighs 0.85 kg/kW only. 3) The speed control of linear as well as rotary actuators can be achieved with ease. By merely adjusting small flow control valve, wide range of speed and feed can be obtained.