Litchfield tuned 991 Can’t get your hands on the latest GT3? Serial supercar tuner Iain Litchfield couldn’t, his solution was to create his dream 911 based on a Carrera T. Photography: Chris Wallbank.
‘To a T’ Litchfield 911 Carrera T 991.2
Litchfield founder Iain Litchfield was fast approaching his 40th birthday, he wanted to add a new GT3 to his fleet but he found that despite his enviable connections, getting onto the list was proving harder than it needed to be. “We’re normally able to source most things,” laughs Iain, “But for some reason, that one seemed to be elusive – despite a letter of agreement from a dealer on an earlier 991. It made me think about taking a different tack and perfecting something a little further down the family tree – when Porsche announced the launch of the Carrera T, it was all the inspiration I needed.”
“The idea of a more subtle car, with some choice modifications, appealed much more than the GT3…”
Quite appropriately for a man that’s made a succession Subarus, then Nissan GT-Rs, and now supercars perform better than their respective factories could have ever envisaged, it seems perfectly natural to think that the easiest route for Iain to create his perfect 911 was to re-engineer one himself. When you consider that Iain is a man that can currently count the technical heads of Nissan’s NISMO motorsport division as his co-conspirators, that’s no real leap of the imagination.
“The car now comes alive with any small throttle input”
On further investigation, the Porsche plan didn’t even feel like a poor relation of the original idea. “I quickly convinced myself this would be the ideal option for me as it was a car I could spec with some of the nice options from the GT cars, like the full lightweight buckets, rear seat delete , GT Alcantara steering wheel and a few other choice options,” Iain enthuses. “In fact, the more I thought about it, the idea of a much more subtle car, with some choice modifications appealed to me much more than the slightly shoutier GT3. And besides, with my commercial head on, the idea of showcasing enhancements for the 911 Carrera range seemed like a much better business proposition.”
If you’re not familiar with this base Carrera specification, the ‘T’ adds a plethora of welcome upgrades and options to its already stellar build sheet – making it a very different car to drive, even before it’s been breathed on. The ‘T’ feels tighter and more urgent as it goes about its business, rewarding the driver with sports PSM suspension that lowers it some 20mm over the standard Carrera. The smaller GT steering wheel adds to the general precision feel, while a short shift on the manual gearbox snicks rapidly through the gears. It’s not just a short shifter either, the ratios have gone the same way. Add in Sports seats – or the lack thereof, lightweight glass, a mechanical rear differential, optional four-wheel steering and Sports exhaust, and you can see why this car is a regarded as a special machine in its own right. Perfect for those that want to arrive somewhere quickly, without letting too many people know that they’re there. If you take a look inside, you’ll also notice that Iain ticked the full carbon seat option, too. In the quest for minimal weight, clearly nothing was too much trouble.
With the car back at Litchfield’s clinical Gloucestershire HQ, and having racked up enough miles in standard trim both on the road and dyno to set a reliable benchmark, Iain’s team turned their collective experience to how to make the car even better. “Once I had driven the car, I was convinced that it just needed an OEM+ style upgrade,” Iain explains. “The car is so pretty anyway, I didn’t want anything drastically different, just lots of tiny detail changes to give it a fresh dynamic edge.”
Early test runs revealed the car to not only hit its stated 370hp figure almost to perfection (372hp as it goes) on Litchfield’s ultra-accurate Maha twin-retarder dyno, but also, it revealed itself to feel like a car with much more on the road, thanks to myriad weight saving options onboard. Or simply not there at all, of course.
“With the shorter gear ratios, the car felt really urgent,” Iain grins. “That may not be much a headline figure in this day and age, but as a package, it all worked incredibly well. I’m sure it’s no coincidence that Porsche chose to use the engine with the smallest, and therefore most responsive, turbos for this spec. It’s the perfect, punchy all-rounder.”
The first real test for the car came at Silverstone with BTCC driver Jake Hill, it revealed a world of potential and the need to enhance the soft front spring set up. Under hard braking the 911’s nose would pitch, lightening the rear and causing the ABS to kick in too early. Litchfield’s considered fix for this was to commission their regular technical partner, suspension giant KW Automotive, to create a spring kit to their design that works with both the PSM suspension and lower ride height. With these installed Litchfield were able to lower the rear by around 10mm (similar to the GT3’s ride height) and to bring the front back in line with a 20mm drop. This slight rake adjustment not only looks superb, but also gives the car better turn-in. With higher spring rates all round than the OEM set-up, particularly at the front, the 911’s dive was drastically eliminated. “The hardest part of this equation was to balance a rate that left ride quality unaffected,” Iain says knowingly.
“The result is a car that still has that factory feel – as is comfortable on a long motorway cruise, but that is so much sharper when switching the dampers to Sport mode.”
While this may have been enough for many, the work continued with modifications to the front arms, to give a set-up precisely akin to the GT3, with an improved, more direct feel and a much more immediate, self-centring weightiness. The final part of the chassis work came in the aesthetically pleasing form of custom wheels spacers, again from KW. These improved the track width, assisting turn-in further, and giving the car a more direct feel.
Iain was clearly happy with progress so far; “We retained the original Pirelli P Zero tyres throughout the chassis development and the transformation was remarkable. With the steering perfected, we were lucky to have the 991 GT3 Touring belonging to a certain Chris Harris to compare it with back-to-back – there is no wanting for feel or precision now. There’s no dead-zone just off-centre, just instant feedback and a lovely pure connection to the road. The chassis has a neutral handling balance with little to no understeer and oversteer when provoked. It’s a totally different car now.”
With a chassis that Stuttgart would be happy to put their top-tier badging on, it was time to find a little more power. Having uprated so many 911s in the past, this was a well-trodden path for the Litchfield team. Ultimately uncorking the exhaust with a combination of parts fabricated in-house, a beautiful Akrapovic rear silencer, and adding their own bespoke ECU calibration would see another perfectly delivered 100hp. “The only conundrum here was where to sit the torque figure, versus the temperatures the intercoolers can actually work with on these relatively small turbos,” muses Iain.
Weeks of further testing saw the team settling on a base remap that produced a comfortable 450hp with 400lb ft of torque (up from 332lb ft). It was now clear that the turbos were working harder against the exhaust back pressure and generating unnecessary heat. But, as this power level and boost profile drove perfectly the decision was made to effect further hardware changes to improve the car’s engine breathing.
In-house, hand-crafted sports catalytic converters were carefully fabricated, allowing yet another slight ECU tweak. After more careful testing, a totally non-stressed 465hp and 440lb ft resulted. “Looking at the data on the dyno and the road it was clear that the engine was running well within itself,” assures Iain. “When you look under the car at the factory exhaust, it was extremely restrictive, especially the manifold design. Akrapovic were claiming a 20+hp improvement from just changing the exhaust. It’s almost like Porsche wanted to throttle the flow into and out of the turbos for some reason.”
The final piece of the jigsaw was the installation of Litchfield’s own tubular headers that offered an equal length design to smoothly merge just before the turbo entry. These not only added yet more of everything that was needed, but more importantly, allowed the turbos to spool much faster, improving the almost immediate throttle response into something utterly instant. “The car now comes alive with any small throttle input and you especially notice it around 2,000rpm, where any car often lives,” a clearly enthusiastic Iain imparts. “The free flowing nature of this exhaust allows the engine to produce over 30lb ft of more torque at 2,000rpm and another 55lb ft at 2,500rpm. The engine’s response is smoother and more urgent at the bottom end of the rev range and it pulls much harder and crisper at the top end. Overall the new exhaust system increases power to 480hp and 450lb ft.’” Think about that for a second. In a factory lightened car that started with just 370 horses.
A perfect tuning package required the perfect road trip test. As usual, a pan European dash would be the essential final stamp of approval before the whole solution could be signed-off for sale. Here, the hard-worked Pirellis were upgraded to N-rated Michelin PS4s. While they may add a little road noise into this civilised package, the resulting increase in grip was considered to be more than a fair trade-off.
What followed was a trip that took in Paris, the Swiss Alps – and all manner of Europe’s best (and worst) roads in a bid to prove to Iain that the car had retained an everyday usability to match its prodigious power and handling. The seventh gear in the manual ‘box proved its worth across many miles, even showing the 911 to be something of a parsimonious fuel sipper at a cruise. Not what you expect from a car like this. While perhaps not the last word in rifle-bolt shifting, Iain was quick to praise its addition to the car’s easy-to-live- with demeanour. As happy on a ribbon smooth straight as it was on a torturous set up undulating bends, it was clear that the car was ready for its final test – and that’s where our shots were taken. It may be a cliché, but there’s a reason that the great and the good of tuning test at the Nürburgring. Its unique set of twists and turns, offering an exclusive set of proving surfaces, corners and braking zones As you might imagine by reading this, the car passed its many tests with flying colours.
“Once we were happy, we put Porsche Championship wining driver and local ace, Moritz Kranz, into the car for his feedback,” says Iain. “Without prompting he proclaimed to love the steering, and was kind enough to liken it to a gentleman’s GT3, without the edginess or stiffness of the normal GT3. His parting words were that the car remains neutral through the bends without excess liftoff oversteer, offering great power. He felt it would make a phenomenal road car. On the drive home, I had to agree with him.”
Since then, many other luminaries have driven the Litchfield Carrera T, proclaiming it to be something of a marvel, enhancing everything that makes the original such a wonderful machine, while adding several additional layers of dynamic ability. “It’s funny really,” Iain concludes, “I set out to buy a standard GT3, but our ‘junior GT3’ is about as good as we could have hoped for. Sometimes not getting what you want allows you to build something you prefer even more.”
“There’s a reason that the great and the good of tuning test at the Nürburgring”