One of the oft-cited drawbacks to turbocharging – and a respect in which the Ford EcoBoost line of engines generally excels – is “turbo lag.” That is to say, it takes time for exhaust gas pressure to build to a point that it can make a turbocharger spin productively. The stereotype usually goes that a turbocharged engine needs to reach at least 3,000 or higher RPM before any real boost pressure can be felt.
That’s not the case with the 1.0-liter Ford EcoBoost three-cylinder, and responsiveness is one of the many reasons that the engine is so lauded by members of the press. As Ford Global Powertrain Technology Communications Manager Pete Seredynski explains, the pint-sized Ford EcoBoost mill uses one of the smallest turbochargers ever engineered, with a turbine diameter of just 1.5 inches. This means that the turbo “spools up” quickly, all the way to an astonishing top speed of about 248,000 RPM – or nearly 40 times the rev-limit of a typical internal combustion engine.
Of course, the turbocharger’s small size and concurrently quick acceleration does come at the expense of some peak performance. In other words, peak psi is quite a bit below that of a larger unit. But the unit’s high max RPM, combined with the relatively low air-flow demands of such a small-displacement engine, means that the turbocharger is just about perfectly matched to this application.