Ford Focus RS 2016 review: tech details

Ford's new mega-hot hatch pushes back the boundaries of what's possible in a production car. We go under the skin for a closer look.

It's been worth the wait for the Ford Focus RS, and we love it. What's just as interesting as its phenomenal performance and bargain basement price is the way that it's all come together.

The $50,990 German-built Focus RS is not a car that's been built with a bottomless budget - far from it. The more that's spent in the development phase, the more the final product has to cost.

It is also being sold into 42 markets across the world, from the sub-zero temperatures of northern Europe to the searing highs of inland Australia, and in the same state of mechanical tune. It's an interesting study in Ford's new world car build philosophy, too.

Let's break it down into its major bits and see how it was done.

Chassis

The Focus sits atop Ford's C1 platform, originally engineered for the previous generation Focus, as well as the last Mazda3 and Volvo S40/V50.

The Volvo connection gave the RS one crucial feature; a transmission tunnel. Without it, all-wheel-drive was off the table.

In order to achieve our cost target, the Focus needs to be built on the line like every other Focus.

The chassis itself is 26 per cent stiffer than a stock Focus five-door shell, but a stipulation of the production process is that the RS must flow down a regular production line.

The head of the RS project, Tyson Johnson, explains.

"In order to achieve our cost target, the Focus needs to be built on the line like every other Focus. That saves us money but limits us in what we can do. So we had to come up with solutions that are easily installable on the line," he said.

"The big problem is that rear rail is incredibly important for rear crash performance. We had to specifically design it to stiffen the rear subframe, but to still collapse when the car is crash tested, so the crash performance is the same.

"We included what we call a lion's foot, that connects the rear shock towers, and which is an integrated part of the body in white – which wasn't easy to achieve. But it improved some local stiffnesses by up to 100 per cent."

Drivetrain

Johnson and his team had actually given up on AWD for the RS after trialling a traditional Haldex system – similar to that found under a VW Golf R or Mercedes-AMG A45 - until they discovered the Twinster rear axle.

Usually found under a Range Rover Evoque, one was fitted to a Focus - and it broke after just two days of testing. Undeterred, the team rebuilt and developed the system over two years until they were happy with it.

The three-piece propshaft spins constantly, and up to a theoretical 90 per cent of drive can be sent to the rear in 0.06sec.

Instead of a rear limited slip diff, a pair of electronically actuated clutch plates, one on each rear driveshaft, distributes torque to the rear wheel that needs it most.

It's also geared to 'overspeed' the rear axle by two per cent, working in conjunction with revised front end suspension geometry to all but eliminate understeer, by 'pushing' the front end into a corner from the rear.

The three-piece propshaft spins constantly, and up to a theoretical 90 per cent of drive can be sent to the rear in 0.06sec.

"We find, though, that the average is more like 70 per cent," said Johnson, but in theory, it can be almost totally rear-driven.

Engine

The 2.3-litre EcoBoost four-cylinder engine under the bonnet of the Focus RS is also found in the Mustang EcoBoost, albeit in a lower state of tune.

Ford's engine partner Cosworth developed a new alloy head for the engine, which is a bored version of the head used on the 2.0-litre EcoBoost motor and built in Valencia, Spain.

A completely revised version of the same turbocharger – with a new compresser housing and impellers - from the 2010 five-cylinder RS replaces the stock item.

The tune of the 2.3-litre is "pretty high", with 1.8bar or 26PSI of turbo boost; the Mustang runs about 1.2bar or 18psi.

The airbox, too, is a new item, and exposes the filter element in a semi-open plastic cage for maximum air entry.

"We modified the intake system completely, including the turbocharger and the large bore exhaust," he said.

"The way to improve engine performance is by minimising exhaust back pressure, and to do that you need a very straight-through exhaust. On a modern car it's almost impossible, and on an AWD car it is impossible! But we've done a pretty good job on this one."

Johnson says that the tune of the 2.3-litre is "pretty high", with 1.8bar or 26PSI of turbo boost; the Mustang runs about 1.2bar or 18psi.

He also pointed to a plastic flap to the right of the front-mounted intercooler. "That's from a Ford Transit," he said.

"We wanted to put the biggest cooler possible in the [front] space right from the outset, but during testing we found it was too efficient, and was causing water condensation to form in the inlet tract.

"The blocker fit perfectly, and didn't cost us anything to develop."

Brakes and suspension

Four-piston Brembo one-piece calipers clamp the large 350mm front rotors, while the 307mm rear units are stopped with one-piston sliding calipers.

The Revoknuckle-equipped front struts have been revised from the previous RS. The knuckles are designed in such a way as to replicate the performance of a double-wishbone set-up by separating steering and suspension movements.

Adaptive dampers from US supplier Tenneco have just two modes; normal and firm. Notably, the firmest mode, which bumps up both compression and rebound damping by a huge 40 per cent, is recommended only for track use. The RS's Sport mode button actually leaves the dampers in Normal mode for fast road driving.

Springs, meanwhile, are 33 per cent stiffer at the front and 38 per cent stiffer in the rear when compared to the Focus ST.

All Ford Performance cars are specced with Michelin tyres, in this case Pilot SuperSport 235/35 R19s.

An optional set of forged 19-inch alloys, which saves almost a kilo a wheel, is available, fitted with stickier, slicker PilotSport Cup 2 tyres.

Check out Tim Robson's video review of the Focus RS here:

Do you have any other tech questions about the new RS? Let us know in the comments below.