The new Ford Focus ST, the global high performance car as they refer to it, comes as standard with an overboost feature for its 2.0 liter turbo engine, which for brief seconds increases the torque, and gives better acceleration. The Ecoboost unit in the ST is very fuel efficient and makes 252 horsepower and 270 lb.-ft. torque. The overboost function is there to make it feel more responsive and sporty.
The 2.0 liter turbocharged engine makes its peak torque at 3,000 rpm. The overboost will extend that to 4,500 rpm for 15 seconds, giving you more pulling power across the rev range. That should be enough to, say, overtake a lorry or get back up to speed after hitting the apex. To make sure the engine copes with the overboost, engineers have tweaked the turbocharger and beefed up the cooling system.
This infographic here may give you a better understanding of the system:
Ford engineers made sure the overclocked EcoBoost 2.0-liter would have a very robust cooling system. “The turbo itself is specified for sustained, high-output performance, but they’ve programmed the car’s computer to dial in more boost past 3,000 rpm to give it that extra something,” says engineer Lisa Schoder, who is Marketing manager for Focus ST.
“We limit peak turbo boost to maintain a wide margin of safety and durability over the life of the car,” Schoder adds. “But overboost is cool in that it tweaks more acceleration through the turbo for brief periods for performance-hungry drivers.”