Ford engineers have created a minor miracle with the new 1.5 liter 3 cylinder EcoBoost engine. For starters, it will power one of Ford’s most popular high performance cars in the UK and Europe markets — the upcoming Fiesta ST. 3 cylinder engines are usually thought of as weak kneed fuel sippers for econo cars like the late and unlamented Geo Metro that plied America’s highways and byways from 1995 to 2001.The engine in those cars made 55 horsepower and had an underwhelming 59 foot-pounds of torque
The new Ford 3 cylinder cranks out 197 horsepower and an impressive 213 foot-pounds of torque. That makes it nearly equal in power to the existing 1.6 liter 4 cylinder engine, but it does so in a smaller, lighter package with fewer moving parts.
Making a three cylinder engine is more complicated than just lopping off one cylinder from a four cylinder engine block and shortening the crankshaft. Three cylinders do not have natural harmonic balance the way a straight six or V-8 engine does. Engineers have to find ways to tame the engine shake that is inherent in the three cylinder configuration.
To make things more complicated, the new Ford 3 cylinder EcoBoost uses cylinder deactivation to shut down one cylinder at certain engine speeds depending on engine load. According to Joe Bakaj, Ford of Europe’s product development chief, this makes the first time that cylinder deactivation has been used for a three pot motor.
Ford currently offers a 1.0 liter three cylinder engine in the Fiesta and Focus. Ford spokeman Dan Jones says the small engine accounts for about 5 percent of Fiesta and Focus sales in the U.S. To control engine shake in that unit, Ford engineered the flywheel and front pulley to balance the engine instead of using an internal balance shaft.
The Ford system is far more elegant as it eliminates the additional friction associated with installing a balance shaft. It also reduces costs by using fewer parts and lowering the amount of time needed to assemble the engine. The company is mum at this point about how it controls engine shake in the new engine when it is running only two cylinders.