The blurb from Ford says:
“It features special technology that filters out unwanted engine noises, while transmitting pleasing sounds straight inside the car for maximum driver enjoyment.”
As one of the most technically advanced engines in production, Ford’s 1.6-litre EcoBoost powerplant combines high-pressure direct injection with twin independent variable cam timing and a low-inertia turbocharger, which provides exceptional power- and torque-to-size ratio without sacrificing weight, size and fuel efficiency benefits.
But there’s a problem if you like a sporty engine note. Turbocharging invariably robs an engine of its natural induction voice, particularly high up in the rev range – the turbo whoosh muffles the sportier engine note.
Ford’s engineers, who have added a ‘sound symposer’ to the 1.6-litre EcoBoost engine, have all but cured the problem. The device is effectively a sound box that collects the engine’s sound frequencies from the air intake, which is then fed directly into car’s cabin.
Ford engineer Ralf Heinrichs explains the technology:
"All engines have their own sound character and it is the exhaust and/or intake system which determines this character. Typically, the exhaust system determines engine sound at low revs whereas higher up the rev range the intake system gives the engine its unique voice."With turbocharged engines, the turbo is an integral part of the intake system and it masks the sound of induction because the whoosh noise becomes dominant when the turbo is spinning at speed."We needed to recapture or recreate that exciting induction noise so what we've done with our sound symposer is capture engine oscillations in the intake system downstream from the turbo and then direct them straight into the cabin for a good sporty growl."
It’s an ingenious bit of kit that was originally developed for the 2005 Focus ST, but is also a feature of the new Focus RS and RS500.
While the 1.6 EcoBoost in the new Focus is obviously not as highly tuned, it is said to deliver a significantly better engine note that the current model Focus.
Interestingly, it’s a highly tuned version of the 1.6-litre EcoBoost that will power Ford’s Fiesta RS WRC car this year.