Focus RS - the next generation


Ford has suggested the next Focus RS could get a clever active front limited-slip differential to tame torque steer in a car that could send as much as 350hp through the front wheels, much as VW is doing with the next-gen Golf GTI. Officially Ford hasn't even admitted it's doing another version of giant-slaying Focus, but of course it is and we're slowly discovering what form it'll take when it arrives in a year or two.

Can an active diff tame a more powerful RS?
Can an active diff tame a more powerful RS?
PistonHeads got talking to the powertrain engineering manager of European performance division Team RS (there's one clue), Len Urwin, who revealed his admiration for the active diff.

"You can drop a mechanical diff in as we did with the previous Focus RS ... but an E-diff would take that a step forward in that you can really optimize traction in all situations," he said. The helical Quaife diff in the last RS coped manfully with the 2.5-litre engine's 305hp, but the car still suffered torque steer and, as Urwin says, the system wasn't programmable.

As we learned in our differential masterclass, the problem with passive front LSDs is that the set-up is always a compromise. An active diff would theoretically remove those compromises.

RS Focuses have tried various diff options
RS Focuses have tried various diff options
Urwin's been up to Sweden in the snow to test an active diff called Twinster made by British engineering giants GKN (who also do the BMW M active diff). He came away impressed. "It works better than I expected," he told us. "It's on the list."

Four-wheel drive is also a possibility, but its use is hampered by the fact that the 4WD systems available within Ford are all the front-wheel biased Haldex type. "It's inherently an understeering system," Urwin said. "We would need to do something we could make fun to drive."

They're also heavy, but as he says, in terms of traction they're still superior to a front LSD.

The engine could be a version of the two-litre Ecoboost seen in the Focus ST, but tuned past the 250hp it makes in the 'warm' hatch. As it was pointed out, the same engine in the Radical SR3 SL makes closer to 300 hp. It would require a larger turbo we were told, but this causes problems. "If you size it too large and capable of too much power you lose bottom-end torque and response," said Urwin.

ST is already hot, RS would be more so
ST is already hot, RS would be more so
This wasn't talked about, but the more likely option is a 2.3-litre version of the Ecoboost rumoured to be under development in the States and capable of around 350hp. What is 99 per cent certain is that the next RS will be a five-door only, for the very good reason Ford hasn't got a three-door version of this generation Focus.

It'll also likely to be sold in the States for the first time, which is a good thing because the sheer numbers will bring economies of scale (ie affordability) for initially expensive integration of hardware like an E-diff.

At the end of the interview, Urwin had a question for us: what did we think PHers wanted in the next RS? We attempted to answer, but the best response would be "read the comments." Here's your chance - over to you!

 

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Comments (433) Join the discussion on the forum

  • Regiment 11 Oct 2012

    What makes the Ford Focus RS, any of the generations, a "giant-slaying" vehicle, when it struggles to beat any of its much less powerful competition?

    It's just a standard hot-hatch sold to people who care more about outrageous style and hp figures than "slaying giants" on the track or on the road.

  • David87 11 Oct 2012

    The RS500 / Mountune MP350 isn't really any more unruly than the standard car with the Mk2, so I guess the Mk3 will get by with FWD. That said, my current Focus RS will be my last FWD performance car.

  • adz13091982 11 Oct 2012

    I'll say it before anyone else does - 350bhp through 4 wheels would be better smile
    But seriously that does seems a lot of power for a FWD car, there must come a point where no amount of power will make a FWD go any faster and handling is compromised.

  • JonLock 11 Oct 2012

    5 door. ruined already!

  • hughcam 11 Oct 2012

    I would like to see an interior that isnt crap

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