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

  • pimpchez 09 Jan 2014

    Just as a quick comparison although its not as focused (haha) , my MPS does exactly the same thing.Its not a Quaife diff , i dont even know what it is actually .

    I do know that it takes focus rs gearbox and diff oil and pulls me round corners so hard that the back end cant keep up .

  • Kenny Powers 09 Jan 2014

    The RS is prone to low speed understeer if you try to turn-in too quickly. Once up to speed I never had any understeer problems. In fact, at the limit on track, its balance is very much oversteer. I definitely wouldn't say its nose led on the limit. In fact in my experience the opposite is true.

  • Johnnytheboy 09 Jan 2014

    Pretty much what I think - the only time mine understeers is in the wet.

    I broke one wheel and bent another - you spend your time dodging potholes!

  • urquattroGus 09 Jan 2014

    Clivey said:
    Thanks for the reply! So how does the BMW feel in comparison (I imagine it's not as "chuckable" and has lower grip limits but is more playful once you've (b)reached them)? The RS strikes me as a car that probably has masses of grip and traction but on the limit handles like any other FWD hatch (understeer). I've not driven one to find out though!
    You are pretty much on the money there. However, the RS did not really under steer too much that I can remember. It would certainly lift off over-steer gently if you wanted it to.

    I think the quaife diff makes it different to an ordinary FWD. If you look at the Renault Megane which is also highly rated it's a similar story.

    Apply more gas and the front seems to drag you round.

    What you did have to worry about more was hitting a pothole or big bump, might knock you off course because it is so stiff. Wrecking the low profile tyre and cracking a wheel is quite possible...




  • Clivey 09 Jan 2014

    urquattroGus said:
    Robbed from post of mine of "Baby Bmw Forum";

    Cornering wise though, the RS was a league above in my book. Very very flat cornering, with stupendous grip, and a more confidence inspiring chasis. The BMW rolls a lot in compasrison, which might actually be good on a bumpy road with the softer setup.

    The quaife diff is a thing of wonder. If its dry, it feels a bit like 4WD dragging you through a corner, you think you have reached the cars limit, but if you are brave enough you just put more power on and it drags the car around.

    There were a few times when I remember agressively driving through a series of clear roundabouts and or sharp bends and I was just astounded by the grip. Always more than you think thanks to the wide track and masses of rubber coupled with the diff.

    The Focus posted the same or better lap time as the for GT supercar around fords Lommel proving ground in Belgium for what I can remember.

    Absoultely crap low speed ride though, and I would never swap back!

    I now have a stealth machine that is quicker and a delight to drive day to day!



    Update: I am going to fit Eibach Anti Roll Bars to the M135i this weekend, and see what kind of improvement there is if any...
    Thanks for the reply! So how does the BMW feel in comparison (I imagine it's not as "chuckable" and has lower grip limits but is more playful once you've (b)reached them)? The RS strikes me as a car that probably has masses of grip and traction but on the limit handles like any other FWD hatch (understeer). I've not driven one to find out though!

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