Mountune Squeezes Unbelievable 684 HP From 2.3-Liter Ford Focus RS Engine

How would you like a hot hatchback with more power than a McLaren 675LT?

byChris Teague|
Ford News photo

Established aftermarket shop Mountune recently posted a YouTube video of a 2.3-liter Ford Focus RS engine making insane power numbers on a dyno, showing that this tiny four-cylinder produces enough twist to challenge an elite list of high-dollar supercars.

The one-minute clip shows the purpose-built EcoBoost producing an almost comical 684 horsepower as it revs its way to 7,200 rpm. Mountune says its engine is running on E30 fuel with major upgrades such as a new head and larger EFR 8374 turbocharger, but there’s no other info on the mods that make this type of power possible. It's worth noting that the horsepower numbers seen at the crank (direct from the engine) tend to vary wildly from the power delivery that actually happens at the wheels, so a dyno run with the engine in a car may look quite a bit different.

With more than 100 horsepower per liter, this heavily boosted power unit is ahead of exotic machinery like the Lamborghini Huracan and McLaren 675LT. Although the Focus RS motor itself has a checkered past, recent examples have been far more reliable—here's to hoping that it can handle Hellcat-rivaling power for more than one quarter-mile pass.

There’s no word on Mountune’s intentions for this powerhouse engine, so we don’t know if another upgrade kit is destined for the company’s catalog, or if the dyno run is just a chance to show off. Either way, there’s no doubt that any car with that engine under the hood is going to be monstrously quick.