Volvo has introduced a new 4-cylinder 2-liter GTDi (Gasoline Turbocharged Direct Injection) engine for its S80, V70, and XC60 models for performance with fuel efficiency. The Volvo-developed turbocharging technology, direct injection, and twin variable camshafts provide low fuel consumption and emissions with high performance across a wide rev range in a compact package.

The gasoline engine, the 2.0 GTDi, produces 203 hp and 300 Nm (221 lb-ft) of torque, with 320 Nm (236 lb-ft) in an overboost condition. "We've succeeded in making a four-cylinder engine that is as powerful as a 2.5-litre 5-cylinder unit, and it's also much more energy-efficient. One of the most important reasons behind the results is our new, patented turbo system that has been tailor-made for smaller energy-efficient engines," says Magnus Jonsson, head of Product Development at Volvo Cars.

Less is more
The turbocharger system was developed by Volvo Cars, Borg-Warner Turbo System, and steel component manufacturer Benteler Automotive. The turbocharger (K03) is the market's smallest in relation to the engine's maximum output. The turbo not only boosts performance but improves exhaust aftertreatment by enabling quick heating of the catalytic converter.

The turbine housing is integrated into the manifold, an efficient design with which Volvo already had experience. But the new manifold and turbine housing are made of sheet steel instead of a casting. The sheet is lighter and more compact and generates less heat owing to its extra insulating layer—allowing high gas flow temperature and thus more efficient combustion.

A sheet steel manifold is nothing new but previously has only been used in combination with cast turbine housing. The integrated turbo package made entirely of sheet steel is an innovation patented by Volvo.

The technology makes it possible to shape the exhaust ducts for optimal gas flow and generate the maximum "tuned" pulse effect for the greatest turbine efficiency. The pulse dynamics permit generating a high power output across a wider range of engine revs, minimizing turbo lag for good acceleration at both low and high speeds.

"High performance is important to many customers. However, being an innovative and highly efficient powertrain, there is also a significant gain in both fuel consumption and emissions with this technology" says Jonsson. "A Volvo S80 with this engine and automatic transmission consumes just 8.3 liters of fuel per 100 kilometers" (28 mpg).

Efficient direct injection quickens turbo
On the direct injection engine, the side-mounted injectors from Bosch have seven holes for precisely controlled injection into each cylinder. Direct injection gives a high fill rate in the combustion chamber, efficient combustion, and low emissions. Because of the high fill rate, the turbo also starts spinning earlier for better response (acceleration) in the low rev range.

Direct injection also allows quick and stable combustion at high loads for smooth engine operation.