In these days of high fuel prices, and the prospect of yet even higher prices in the immediate future, the car buyer is more than likely to be interested in vehicles that can provide better fuel efficiency, and better still, vehicles that offer fuel economy without any sacrifice to the power output.
Volkswagen Group may have hit the jackpot with their latest engine, the TSI, that uses a combination of a supercharger and turbocharger. The idea of a supercharger and turbocharger combination is not new. Those who are old enough may recall the Nissan March super-turbo, introduced in the early nineteen eighties. The result was a potent little car that went like stink, and it even made the world rally scene. Some of us remember Per Ekland and his March Super-turbo flying through the special stages in the Rally of Malaysia.
There was a small difference, however, and that was the fact that at that time, the development objective was to generate more power from an engine, not fuel economy.
Today, the TSI is Volkswagen’s version of the supercharger-turbocharger engine. This time, the idea is to make an engine of smaller capacity more powerful, especially at take-off, and then when it is running, maintain high torque characteristics to keep the vehicle going. Underlying all this was the aim to improve overall fuel consumption, and reducing the absolute engine capacity for a given size of vehicle, again in the interests of reducing fuel consumption.
Having a small engine is the first step towards improving fuel economy, but this always comes along with the lack of power, therefore restricting the maximum weight of the vehicle. The paradigm was always, small car, small engine, and large car, large engine. The TSI engine has specific characteristics that now allow a large car to be fitted with a small engine. QED.
Following the success of their Fuel Stratified Injection (FSI) engines that have been successfully utilized in many of their current models, Volkswagen introduced the TSI engine, the world’s first direct injection twin-charger, gasoline engine, designed to not only producing optimum horsepower and driving pleasure but at the same time managing fuel costs efficiently.
Dr Hermann Middendorf, Head of Development Department, Volkswagen’s TSI expert from Germany, presented an overview of the TSI technology and the superiority of TSI over conventional gasoline engines.
The TSI engine uses a modified injection technique, in which a multi-hole high-pressure injection valve with six fuel exit openings is used. Similar to the FSI system, the injector is located on the entry side between the entry canal and cylinder head gasket level. The amount of fuel to be injected requires a high spread in the flow-through amount; hence the maximum pressure is increased to 150 bar, and the engine runs a compression ratio of 10:1.
Although it has a relatively small capacity of only 1.4 litres, the TSI produces an incredible maximum torque of 240 Newton metres, available from 1500 rpm to 4750 rpm. Absolute horsepower is 125kW / 170PS horsepower, a performance level easily matching a 2.0 liter naturally aspirated engine, and a top of the range TSI engine can outperform a 2.5 liter engine with ease.
Winning the “Best New Engine” at the 2007 and 2006 International Engine of the Year awards, one of the most sought-after automotive accolades, the TSI engine has a supercharger which is belt driven, will supply boost pressure from off-idle, to increase the torque during low RPM engine speeds, and a the turbocharger that comes to life at the higher RPM range, effectively running dual forced induction mechanisms. Turbochargers need high revolutions to ‘spool’ up before they become effective, and this makes them not so effective at lower engine revolutions. A supercharger, being mechanically driven, does not suffer any lag, and is able to provide power instantly for the initial take-off. At higher engine revolutions, the supercharger begins to lose its effectiveness, due to the drag caused by its mechanical drive, and is electronically disengaged, allowing the turbo to take over the work.
To achieve a seamless transfer from the supercharger to the turbocharger, the TSI diverts pressurized air from the supercharger into the turbocharger to ‘kick start’ it every time there is a switchover. This process is continuous and a sealed clutch is used to switch the supercharger on and off when necessary.
All the power aside, the main attraction of the TSI engine is its fuel economy. The 1.4 TSI engine’s fuel consumption averages around 7.8 litres / 100km (12.8km/ litre), whereas a conventional 2.0 liter engine, averages a significantly higher consumption of 9.7 liter/ 100km (10.3 km/ liter). This comparison with a 2.0 litre engine is by virtue of the fact that he 1.4 litre TSI has roughly the same power as a 2.0 litre engine.
The TSI is more environmental friendly. CO2 emissions have been significantly reduced and are comparable to an engine of lesser output. The TSI engine manages to reduce CO2 emissions from 161g/km to 149g/km, making it more environmentally compliant than its peers.
The Volkswagen TSI engine is available in the Golf, Jetta and Touran models in Europe. More than 41,000 Volkswagen vehicles fitted with the TSI engine were sold in a short period of less than a year. The new Tiguan has also started with a version of the TSI engine. Even as we pen this article, a natural-gas powered TSI is being tested on board a Passat – a reflection of the great potential of this unique new economical and “torquey" engine generation.
This TSI is one engine that is worth a second look, and Malaysians will see it in 2008 in the Touran, due to come here, and later on in the Tiguan.
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