The Downsizing Agenda
The Turbo Effect
A turbocharger uses an engine’s exhaust gas to drive a turbine wheel at speeds up to 280,000 rpm, working in harness with a compressor wheel to suck in and compress large amounts of ambient air.
This compressed air makes the combustion process cleaner and more efficient, meaning that turbodiesel vehicles are up to 40 percent more fuel efficient – up to 20 percent in turbo gasoline cars – compared with non-turbocharged gasoline vehicles of equivalent power ratings.
Turbos are also helping deliver new benchmarks in performance – boosting the driveability that makes cars fun to drive and developing the torque that helps trucks move goods around the world’s highways.
Accelerating Engine Downsizing
Turbos play an important role in increasing power density, which is defined as the ratio between power output and engine size. This characteristic makes turbocharging a key enabler of engine downsizing, perhaps the most important auto industry trend of the modern era. Downsizing is the reduction of the engine size, for example the substitution of a large V8 naturally aspirated engine with a smaller turbocharged V6 or likewise the replacement of a non-turbo V6 with boosted 4 cylinders, while maintaining a similar levels of power and torque.
The smaller size makes the engines more efficient and also brings additional advantages such as a quicker engine warm-up (which reduces cold-start emissions) and lower weight (which further helps fuel economy).
All major manufacturers are currently planning to expand their line-up of downsized engines. Consequently, the impact of turbos over the next 10 years will include a reduction of average engine displacement in the US from 3.6L to 3.0L. In Europe, 4 cylinders will remain the architecture of choice, but reducing from an average 1.7L to 1.5L or smaller. China – where the turbo experience is more recent – will see a downshifting of a similar magnitude.