New developments keep improving fuel efficiency
If you were to assess the future of the automobile on the basis of media coverage alone, you might conclude that the internal combustion (IC) engine is doomed and the future is wholly electric. Maybe someday, but don’t lay off your engine techs just yet.
For sure there will be a place for electric vehicles (EVs). And the proportion of hybrid-electric vehicles (HEVs) in the mix will almost certainly increase. But electric power won’t replace the IC engine for a while yet.
Impact of CAFE standards
The driving forces behind the move toward electrification are the onerous fuel-consumption standards the industry is facing from now until at least 2025. Corporate Average Fuel Economy (CAFE) standards in the U.S., with which Canadian regulations are typically harmonized, are set to increase to 34.1 mpg (US) (6.9 L/100 km) by the 2016 model year. That equates to an overall 4.3 percent reduction in fuel consumption every year between now and then.
But it doesn’t end there. This summer, U.S. President Obama announced that the CAFE standard will increase to 54.5 mpg (US) (4.3 L/100 km) by 2025. That’s a level achieved only by the Chevrolet Volt, Nissan Leaf and Toyota Prius, among vehicles currently available in Canada.
EVs not only answer
As much as many people, President Obama included, would like to see those goals achieved by a wholesale switch to EVs, it’s not going to happen. It’s simply not practical to do so because of the significant limitations EVs impose on driving range and the extended time they require for recharging.
It’s possible that, between now and 2025, some technology breakthrough will make possible EVs that can consistently travel 400 km between charges and can be recharged in 10 minutes. But it’s unlikely. Which means that automakers can’t count on EVs to take them to the CAFE promise-land.
It also means that they’re stuck with the IC engine to get them at least part-way to those lofty fuel-economy goals. For even if hybrids become the norm, they still need an IC engine as part of their powertrain.
Consequently there is more development activity currently happening on the IC engine than perhaps ever before. Because there has to be!
Widespread technology adoption
There are many paths to reduced fuel consumption – including several outside the engine. But at the core of the issue is engine efficiency. By their nature, IC engines are inefficient, typically converting only about 25 per cent of the energy potential in the fuel to useful work, at best, and much less than that most of the time. (Diesel engines are slightly more efficient than gasoline engines.)
The introduction of such high-tech features as variable valve-timing and lift and direct fuel injection, along with overhead-cam, multi-valve cylinder-head design, have made significant strides toward improved efficiency. They are well on their way to becoming standard features on all new engines.
Turbocharging is also making a comeback as a means to achieve a desired level of power output when it is needed from a smaller engine that is more fuel-efficient when maximum power is not required. Advances such as variable-vane geometry have improved their throttle-response characteristics and today’s turbochargers are far more reliable than their forebears.
Back to fundamentals
All those technologies play a role in what goes on in the combustion chamber, where the fuel is ignited to produce power. That is where the greatest efficiency gains may yet be realized as engineers get back to basics, focusing on the combustion process itself.
Mazda, for example, is introducing a new suite of technologies called SkyActiv that encompass significant efficiency improvements in the engine, resulting from a major reassessment of its fundamentals. The pistons in that engine employ pop-up domes with recessed pockets where combustion is initiated – looking more like they belong in a diesel than a gasoline engine. The compression ratio is 13:1 – unheard of outside a racing engine – and it runs on regular 87-octane gasoline, thanks in part to a rethink of the fuel-injection timing and distribution pattern.
Audi is working on a combination of direct and indirect injection that promises to improve efficiency over the whole range of engine speed and load. And several automakers are working on Homogenous Charge Compression Ignition (HCCI), which combines the best features of gasoline and diesel engines together in one.
The bottom line is, there is a lot of life in the IC engine yet. And the tough fuel consumption targets they must meet are motivating engineers to find new and innovative ways for increasing its efficiency. So don’t count it out yet.
