Gothenburg, Sweden - If the engine in these picture looks a bit like a backyard special, that's to be expected. Volvo calls it the High-Performance Drive-E Powertrain Concept - which means it's an experimental one-off, straight out of the back room at Gothenburg.
This 'concept' is a two-litre, biturbo petrol four that delivers a reliable 330kW - that's 450 industrial-strength Swedish horsepower in the old language - without any discernable turbo lag.
Volvo vice-president of powertrain engineering Michael Fleiss explained: "There are several high-power small-size applications available from other manufacturers where one large turbo is used to create a high level of power - but the driving experience suffers due to slow engine response."
"We were among the first car companies to offer a broad range of turbo technology, back in 1981, and we felt we could do better than that.
The concept engine uses two parallel turbochargers - two small turbos spool up much faster than one big one, for obvious reasons - but at the level of boost required to deliver 165kw per litre, there was still too much turbo lag.
TURBO NUMBER THREE
So Fleiss and his whitecoats added a third 'hair-dryer' - an electrical turbo-compressor, essentially half a turbocharger powered by an electric motor. The compressed air from this compressor, rather than being fed to the cylinders, is instead used to spool up the two parallel turbochargers.
Fuel is fed by a dual fuel pump working at 250 bar pressure. With this kind of power density, this triple boost installation and unique fuel system, provides drivability without discernable turbo lag, compared to a single-turbo set-up.
The proposal attracted the attention of Volvo suppliers AVL an d Denso, as well as Polestar racing engine director Mattias Evensson.
"This was a very exciting project," he said, "as we pioneered a combination of technologies in the same application, and the result is a quite unique engine with high power yet quick response.
"Its compact size also improves weight distribution between the front and rear axles and lowers the centre of gravity - two factors that have a significant effect on handling, whether in a race car or a street car."
WHY THE BIG FUSS?
Compact powertrains free up space and weight in the structure of the car, which can be used for electrification and emissions reduction, according to Volvo.
With Drive-E, its current eight engine architectures are gradually being replaced by only two: a two-litre four-cylinder Drive-E petrol engine and a four-cylinder Drive-E diesel of the same size.
These two engines - developed in-house at Gothenburg and built in the Volvo engine plant at Skövde - can be configured to meet the power-output needs of the whole Volvo range, all using the same, newly-developed eight-speed auto transmission produced in the same plant.
More than that, the Drive-E engines are prepared for future electrification from the start. Key components, such as the integrated starter-generator, can be connected easily.
The compact size of the four-cylinder engines means that the electric motor can be installed in the front or rear of the car, with the battery pack under the floor in the middle of the chassis where its unavoidable extra weight will do the most good.