TurboCharger

When people talk about race cars or high performances sports cars the topic of turbochargers usually comes up. A turbocharger is defined as" an exhaust gas driven forced induction supercharger used in internal combustion engine”. It is used to boost an engine's horse power without significantly increasing its weight. This differentiates it from a normal supercharger which uses a prime mover to power the compression device.

A turbocharger consists of a turbine and a compressor linked by a shared axle the turbine inlet receives exhaust gases from the engine exhaust manifold causing the turbine wheel to rotate. This rotation drives the compressor, compressing ambient air and delivering it to the air intake of the engine. The objective of a turbocharger is the same as a normal supercharger: to improve upon the size-to-output efficiency of an engine by solving one of its cardinal limitations. The application of a compressor to increase pressure at the point of cylinder air intake is often referred to as forced induction. Centrifugal superchargers operate in the same fashion as a turbo; however, the energy to spin the compressor is taken from the rotating output energy of the engine's crankshaft as opposed to exhaust gas. For this

reason turbochargers are ideally more efficient, since their turbines are actually heat engines, converting some of the thermal energy from the exhaust gas that would otherwise be wasted, into useful work.

One of the first applications of a turbocharger to a non-Diesel engine came when a GE engineer, Sanford Moss attached a turbo to a V12 liberty aircraft engine. The engine was tested at 14,000 feet to demonstrate that it could eliminate the power losses usually experienced in internal combustion engines as a result of altitude. Turbochargers were first used in production aircraft engines in the 1930s before World War-2.The first production of turbocharged automobile engines came from General Motors in 1962.In Formula One, in the so called "Turbo Era”, engines with a capacity of 1500 cc could achieve anywhere from 1000 to 1500 hp (746 to 1119 kW).Renault was the first manufacturer to apply turbo technology in the F1 field, in 1977.

Since a turbocharger increases the specific horse power output of an engine, the engine will also produce increased amounts of waste heat. This can sometimes be a problem when fitting a turbocharger to a car that was not designed to cope with high heat loads. This extra waste heat combined with the higher compression ratio (more specifically, expansion ratio) of turbocharged engines contributes to slightly lower thermal efficiency, which has a small but direct impact on overall fuel efficiency. Turbochargers can be damaged by dirty or ineffective oil, and most manufacturers recommend more frequent oil changes for turbocharged engines; many owners and some companies recommend using synthetic oil, which tend to flow more readily when cold and do not break down as quickly as conventional oils. Because the turbocharger can get hot when running, many recommend letting the engine idle for one to three minutes before shutting off the engine if the turbocharger was used shortly before stopping.

Advantages:

· More specific power over naturally aspirated engine. This means a turbocharged engine can achieve more power from same engine volume.

· Better thermal efficiency over both naturally aspirated and supercharged engine when under full load.

Weight/Packaging, smaller and lighter than alternative forced induction systems and may be more easily fitted in an engine bay.

Disadvantages:

· Lack of responsiveness if an incorrectly sized turbocharger is used.

· Cost. Turbocharger parts are costly to add to naturally aspirated engines.

· Lag can be disadvantageous in racing. If throttle is applied in a turn, power may unexpectedly increase when the turbo winds up, which can induce wheelspin.

Prepared by- Harshil Bhatt

U. V. Patel College Of Engineering