Volvo "Triple Boost" Engine Uses Twin Turbos plus E-Compressor

October 23, 2014

Stuart Birch

New generation Volvo XC90. At present the most powerful version is the plug-in hybrid T8.

The old automotive adage that “there’s no replacement for displacement” is consistently challenged by automakers as they follow the downsizing road. Now Volvo has come up with a 2.0-L four-cylinder engine that produces a claimed 450 hp (331 kW) and could be offered in the company's latest generation XC90.

Its novel boosting system features a bi-turbo configuration supported by an electrically-driven compressor, ensuring maximum power and linear torque delivery. Volvo is the latest OEM to probe the potential of e-boosting (see Audi’s latest development: (Testing Audi’s New E-Booster Reveals Turbocharging's Future).

Volvo describes the engine simply as “triple boost technology.” It is part of the company’s Drive-E development program, the downsizing criteria for which include “attractive and usable power” for broad scale emissions reductions.

Energy dense: Volvo's new 2.0-L engine produces a claimed 331 kW. Note dual turbochargers.

Volvo R&D Chief Dr. Peter Martens has supported links to motorsport technology in the development of the company's powerful new downsized 2.0-L engine.

When Volvo launched the Drive-E family in 2013, its stated aim was to deliver advanced four-cylinder engines based on emissions and fuel consumption relative to performance and drivability. “We knew that 320 hp (236 kW) in our gasoline configuration was just a starting point,” says Dr. Peter Mertens, Volvo Car Group’s Senior Vice President for R&D.

The new engine is currently in development. The two parallel turbochargers are linked to the electrically-powered compressor, which spools up the turbos lower down in the rev range than is typical, thus virtually eliminating lag. A fuel pump working at a high 250 bar (3626 psi) is also an important part of the system to achieve Volvo’s driving experience targets.

Volvo worked closely with suppliers, including AVL, BorgWarner, Valeo, Denso, and Volvo Polestar Racing, from the engine’s concept stage. It regarded racetrack expertise as an essential part of the project to achieve required power density.

This density allows for compact package size and reduced weight, compared to an engine of six or eight cylinders, making for improved front/rear weight balance and a lower center of gravity.

The new engine, regarded by Mertens as an important part of Volvo’s Drive-E program, uses common architecture for both gasoline and diesel power units.

Detail image showing parallel BorgWarner turbochargers which operate in conjunction with an electric compressor.

At present, Volvo is not talking dates for the introduction of the new race-bred 2.0-L nor which vehicle model might take it. But the new XC90 looks a likely contender; in the past its engine range included a V8.

Currently the most powerful version of the new XC90 is the gasoline plug-in hybrid (PIH) T8, which is also turbo and supercharged. It produces a claimed 236 kW (316 hp) at 5700 rpm, with 400 N·m (295 lb·ft) available from 2200 to 4500 rpm. Its electric motor produces a supplemental 59 kW (79 hp).

The latest XC90, which was publicly unveiled at the 2014 Paris Motor Show, is the first to be built off Volvo’s scalable modular architecture and has received a positive reaction. The car is built alongside other models, including the XC70, at Volvo’s Torslanda, Gothenburg, plant where the workforce is being increased by some 1300 in 2015, representing a near 40% boost in numbers. Volvo is looking to achieve a total 470,000 unit sales figure for 2014, about 10% up on 2013.

A new body shop is part of Volvo’s manufacturing expansion plans at Torslanda. This will help provide a capacity there of around 300,000 units per annum.