three cylinders rising
The curtain may be dropping on the five, but it’s prime time for another prime-cylindered engine: the three. In almost the same breath as he announced that his company was getting out of the five-cylinder business, Volvo RD boss Peter Martens revealed the Volvo Environmental Architecture, which will encompass new 2.0-liter four-cylinder and 1.5-liter three-cylinder direct-injection gas and turbo-diesel engines. The goal is to shave up to 200 pounds while boosting fuel efficiency by 35 percent.
Threes are new to Volvo, but other brandsFiat, GM, Honda, Mitsubishi, Smart, Subaru, Suzuki, and VW among themalready sell them in markets where minimizing costs is crucial. Ford recently added a 1.0-liter three-cylinder to its portfolio, and BMW is developing one, too. Fiat even launched a 0.9-liter two-cylinder in the European-market 500, to seriousand surprisingcritical acclaim.
With 240 degrees of crank rotation between power pulses, threes tend to be uncouth. Like fives, they suffer from primary and secondary rocking couples. And, as in fives, these forces are calmed in threes with counter-weights and mount tuning. Computer-aided design has helped minimize reciprocating masses, easing the task. And, thanks to direct injection and turbocharging, power is usually not an issue. Ford has said it will offer the 1.0-liter engine here (in the Fiesta and possibly even the Focus); other brands are sure to follow suit.