Turbo Chargers - When shove comes to push

Published in City Tribune - 16 April 2007

By Tushal Bhadang

The modern internal combustion engine is without doubt a marvellous invention, starting from producing a meagre 2 - 4 horse power (bhp) from to todays 1000 bhp road rockets.

Ever wondered what the ‘Turbo’ or ‘GTi’ bezzle at the back of a hatch or a truck meant? Some time in the 1920’s, lightning struck and designers analysed the way a normally aspirated car engine worked and they came up with a way to shove more air into an engine to increase the compression of the fuel air mixture in the cylinder so that the pop from the spark plug turned into a controlled bang!

Welcome the arrival of the airy Turbo Charger or Supercharger (for super cars)

So you ask, what good is a turbo charger? Well, for starters most normal road cars are normally aspirated. Which means the air in the air-fuel mixture passes through the air filter and then gets pushed into the engine with the fuel into the combustion chamber.

A Turbo charger is basically an air pump fitted on the engine in such a way that the exhaust gases that exit the engine, are used to rotate a turbine (fan) which creates a vortex of air to shove it into the engine though the intake passage.

A 1.8 litre normally aspirated car engine would generate between 120 to 150 bhp depending on the compression ratio of the engine which can vary from 9:1 to 10.5:1, where higher the ration, more expensive it is to manufacture and also it would require higher octane fuel. So, if one were to bolt on a turbo charger to the same 1.8 litre engine, it can be tuned to produce over 300 bhp which is double the original engine output.

Turbo chargers are not plug and play accessories that you have for your computer, a significant amount of mechanical and electrical modifications go into the process of converting an engine to use a turbo charger. Though factory fitted cars with turbo chargers are best as there are minimal hassles on their maintenance and have been tested extensively for compatibility.

We’ve now shown you the advantage of a turbo charger, now to focus on its drawbacks. The turbo charger actually only starts working at a certain engine RPM (Revolutions per minute), which means if you are looking for power at 1000 RPM, forget it! The Mitsubishi Evo 8 (400 bhp tarmac shredder) car uses power from the turbo charger at 3000 RPM (which is pathetic!) but if you keep the car in the right power band and the right gear the same turbo will give you power when you need it. The reason for this is that the Evo 8 is fitted with a massive turbo charger for its 2 litre, 4 cylinder engine! A larger turbo means more power but it also means you need more revs to get it spinning. While a smaller turbo on the New VW Golf GTi will give you only 220 bhp but the turbo starts working even at lower RPM’s as low as 1000 RPM. So you see, bigger is not always better.

In the recent Yalla Bahrain Drift event at the BIC, most of the cars were equipped with turbo chargers so that they could transfer a heap of power to the rear wheels to spin them ferociously which helped them to drift.

Turbo chargers have long been used in diesel engines as well, which are much heavier than their petrol counterparts. The power output is low compared to a petrol engine of the same capacity as combustion is via compression and not ignition. A turbo helps diesel engines rev up faster so that they reach their max potential sooner by improve torque output for lugging heavy loads.

Turbo chargers prevent the loss of power at high altitudes, thus providing significant advantages to turbocharged trucks and off-road machinery. They harness and recycle the energy by reusing exhaust gases to produce more power. As a result, turbocharged engines deliver significant fuel cost advantages over their naturally-aspirated counterparts.
Today’s turbocharged diesel engines produce 50% less NOx and CO₂ emissions than conventional engines.
They also deliver greater torque which, in turn, translates into improved performance on the road and make driving a real pleasure. So what are you waiting for? Get charged today!