With the introduction of the new Maruti-Suzki Fronx, India’s largest carmaker brought back their ‘Boosterjet’ engine. The ‘Boosterjet’ is a small one-litre (1,000cc) motor. But thanks to a turbocharger, it can churn out over a hundred horsepower. Maruti-Suzuki has just rejoined the turbo party. Hyundai, Kia, Nissan-Renault, Skoda-Volkswagen and Tata Motors have all been equipping their vehicles with small-capacity turbocharged engines. Recently, French carmaker Citroen revived the small turbocharged engine on the C3 hatchback, which conforms to the latest emissions standards.
Turbocharged variants of slightly bigger petrol engines have been around for a while, most luxury vehicles have turbocharged petrol and diesel engines. But now, turbocharged engines are becoming increasingly common on smaller 1,000-1,500cc engines. Turbocharging allows carmakers to increase the peak power output from a powertrain. While a turbocharger adds complexity to an engine, it can make a moderately-sized 1.5 litre engine, like the one on new Hyundai Verna, produce a quite surprising 160 horsepower. A ‘naturally aspirated’ engine of the same size available from the same carmaker produces just 115 horsepower.
Before I continue, those more pedantic among you might object to me using ‘horsepower’ as the unit to refer to the power output. So I can shift to PS or ‘PferdStarke’, which is equal to 98.6 per cent of an imperial horsepower. In fact, PS is the measure most carmakers use today, essentially because it gives a bigger number.
The Hyundai Verna 1.5 Turbo, whose manual variant I’m currently driving as a long-termer actually has 158 imperial horsepower but in ‘PferdStarke’ unit, it will translate into160PS. To be absolutely precise in power measurements, one should use the metric measurement of a ‘watt’ to denote power. But oddly enough, despite PS being a German term, most German carmakers use kilowatts to denote engine output.
Sorry for the diversion, back to the turbocharger bit.
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What is a turbocharger
A turbocharger is often described as ‘forced induction’. It works by taking the hot exhaust gases from the engine and running a small turbine that draws in more air from outside than an engine normally would. While the analogy is a bit forced, it is like a ventilator in a hospital. There are also superchargers, where instead of the exhaust gases, the engine shaft itself runs a fan to draw in more air, but superchargers are only viable on larger engines. These ‘forced induction’ engines are different from naturally aspirated ones. A certain amount of the engine’s power is needed to run the turbocharger itself, which is why the turbocharger does not usually kick in until the engine gets to between 1800-2500 revolutions per minute.
When the turbocharger does kick in, it gives a wave of torque like a diesel engine, but unlike a diesel engine a massive wave of top-end power as well. “The combination of torque and power on these engines is what I believe attracts buyers,” Tarun Garg, Chief Operating Officer, Hyundai Motor India Limited tells me.
Formula 1 cars today use a 1600cc engine coupled with a turbocharger and a hybrid-battery system. And the most powerful units have a power output of almost 1000 horsepower.
Unlike a Formula 1 engine, the turbocharger on a car like the Hyundai Verna or a Citroen C3 has to last the life of the vehicle and also be economical, at least similar to that of the naturally aspirated version of the same car.
Turbochargers in the 1970s and 1980s produced a lot of power but were unreliable and thirsty. Today’s cars increasingly use ‘Variable Geometry Turbochargers’ where the vanes inside the induction turbine can shape their orientation depending on the speed of the engine. Not only does this allow the turbocharger to work on a wider band of power, but also makes it more efficient, particularly at lower speeds. On the Hyundai Verna for example, while the naturally aspirated and turbocharged engines are of a similar capacity, according to the fuel economy certified by the Automotive Research Association of India (ARAI), the turbocharged version at an economy of 20.6 kmpl is more efficient than the naturally aspirated version at 19.6kmpl with their automatic transmissions. In the real world, however, the turbocharged manual Verna (that is certified at 20kmpl) is giving me just under 12kmpl, which for a car of its size and performance is not bad at all.
“Modern technologies have allowed us to make the turbocharged engine almost as efficient as the Variable-Valve Timing (VVT) naturally aspirated engine,” Maruti-Suzuki Chief Technical Officer, C. V Raman told me at the launch of the Fronx. And it is this combination of economy and power that is enticing buyers. What is left unsaid is that the government has, through stricter emissions norms, almost removed diesels from the market.
From a driving perspective, turbocharged petrol cars are great fun. The rush of power through the middle and top end of the rev-range makes them extremely enthusiast friendly. With a manual transmission, turbocharged cars encourage you to adapt your gear changes depending on what you want, economy or fun. You can ‘ride the turbo’ or by quick shifting, not really let it kick in completely. Turbocharged cars like the Verna can get to higher speeds very quickly and more efficiently. Once at those speeds, they don’t need to drink a lot of fuel.
Even the smaller turbo engines on vehicles make these cars—Maruti-Suzuki Fronx, Citroen C3 and Hyundai i20—a lot of fun to drive and open up the true handling capabilities of modern vehicles. They are not for everyone, turbochargers are complicated and expensive. For example on the Fronx, Maruti-Suzuki charges a Rs one lakh premium for the turbocharged version when comparing the Delta+ specification with a manual transmission. But turbocharged engines are better than before and those who want to have a bit of fun on the side, they’re here to stay.
@kushanmitra is an automotive journalist based in New Delhi. Views are personal.
(Edited by Anurag Chaubey)