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Child Safety in Cars
Hybrid Cars 2010
Marine Diesel vs. Gasoline 2010
Air Bags 2010
TurboCharging 2010
Drive-Train System 2010

Motorcycle Helmets 2010
Driverless Car 2010 
Tires Not Just Rubber 2010
Car Aerodynamics  2011

Pascal Hayek


Many car enthusiasts have come across the word "turbo" without understanding what it stands for. When asked, very few are capable of explaining how the turbocharging system works.

When people talk about race cars or high-performance sports cars, the topic of turbochargers usually comes up.

The word "turbo" has always been equivalent to "more power" and "high performance" but how is this achieved?

It's a simple idea of compressing air into the cylinders. 

The main job of the turbocharger is to force air into the engine by compressing it, therefore allowing more air to fill the cylinder. More air means that more fuel can be added, therefore resulting in an increase in horsepower. 

I would like to explain turbocharging in a simple way that anyone with the basic knowledge of Science can understand it, but before going further in the description, I need to go to the basics of an internal combustion engine i.e a car engine that runs either on gasoline or diesel. 

The three main elements that cause a car engine to run are: fuel, air and a spark.

Inside the engine a mixture of fuel and air are ignited by a spark and therefore energy created by the combustion causes the engine to run. 

The function of various parts of the engine is to convert that energy which results from the combustion of air and fuel, into a rotational motion. 

When the engine is cranked by turning the ignition key to the run position, the starter motor turns the engine and causes the pistons to move inside the cylinders.  

The downward movement of the piston inside the cylinder causes air to be drawn and fill the cylinder. As the piston moves up to compress that air, the fuel injector injects fuel on top of the piston. So now the compressed air/fuel mixture is ready to be ignited by the spark from the spark plug. The result is an explosion which pushes the piston down and therefore causes the engine to keep on turning. The combustion of the air/fuel mixture results in burnt gases which are expelled from the exhaust system. 

This cycle repeats inside all the cylinders in a sequence and that's how an engine keeps on running.


A story of two wheels 

Refer to the illustrations below in order to understand the turbo.Hot exhaust gases leaving the engine after combustion are routed directly to the turbine wheel side of the turbocharger to make it rotate. That turbine wheel is connected by a shaft to a compressor wheel. As the turbine wheel spins faster and faster, it causes the compressor wheel to also spin quickly. The rotation of the compressor wheel pulls in ambient air and compresses it before pumping it into the engine's cylinders. 

The basic principal behind turbocharging is fairly simple, but a turbocharger is a very complex piece of machinery.


Not that simple 

In fact there are lots factors that are taken into consideration when designing a turbo system. 

Since a turbo can reach speeds of 150,000 rpm and since hot exhaust gases pass through it to spin the turbine wheel, a lot of heat is generated to a degree that the turbo can turn into amber color. The cooling and lubrication play an essential role in turbo design as well as the materials utilized in the design of the housing, the shaft bushings and the turbine and compressor blades. 

Turbo plumbing 

The boost pressure that a turbo creates can reach up to 1.5 to 2.0 bars. (22-30 psi).

Over-boosting may cause damage to the engine piston and to other parts of the engine. The turbocharger's exhaust gas flow is regulated with a wastegate that bypasses excess exhaust gas entering the turbocharger's turbine, thus preventing over-boosting. 

As you may have guessed, the compressed air leaving the compressor wheel housing is very hot as a result of both compression and friction. So what's needed is a way to cool that air down before it enters the cylinders. That's where an intercooler (or "heat exchanger") comes in. It reduces the temperature of the compressed air so that it is denser when it enters the cylinders (heat causes things to expand, as we all learned in science class). The charge-air cooler also helps to keep the temperature down in the combustion chamber. 


The turbocharger was invented by Swiss engineer Alfred Buchi, who had been working on steam turbines. His patent for the internal combustion turbocharger was applied for in 1905. Diesel ships and locomotives with turbochargers began appearing in the 1920s.

Turbochargers were first used in production aircraft engines in the 1930s prior to World War II.

The first production turbocharged automobile engines came from General Motors, the A-body Oldsmobile Cutlass Jetfire in 1962.

BMW led the resurgence of the automobile turbo with the 1973 2002 Turbo, with Porsche following with the 911 Turbo, introduced at the 1974 Paris Motor Show.

Nowadays most car manufacturers have introduced turbochargers on some of their models.

In the racing world almost all cars are equipped with a turbocharging system. 

To end this article, we may conclude that turbocharging has many benefits. 

The benefits of turbo-charging in both passenger car and commercial vehicle applications include greater power and torque for a given engine size, improved fuel economy at part throttle and potentially reduced emissions.

Pascal Johnny Hayek B. Eng. AUB, 1983 Service Manager Porsche Service Centre, Kuwait


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