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by Richard Lane 14 July 2019 Follow @@_rlane_ Share
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You’re looking at the second-generation Porsche 718 Cayman GT4, and therefore your new departure point into the big-winged world of Porsche’s quickest and sweetest creations.
You’ll remember the old Cayman GT4. It was the first time the brains behind the 911-based GT3 and GT2 track day specials were allowed a proper go at a mid-engined model, and they built near-as-dammit the perfect driver’s car. Naturally, the basic recipe has hardly changed. The front axle is still taken wholesale from the GT3, although the 20in wheels are unique to the GT4. At the rear, the architecture is again largely carried over from the common Cayman, but the dampers are inverted in true motorsport style and the control arms and subframe are pure GT3.
Confidence? Doled out by the bucketload, and more so when the two-way adjustable dampers are left in their more relaxed setting. We’re not sure any other mid-engined series-production car communicates grips level this wellRichard LaneDeputy road test editor
It goes on: the engine remains paired to a short-throw six-speed manual gearbox, with drive delivered to the rear wheels through a mechanical limited-slip differential. You still get semi-slick tyres in the form of Michelin’s Pilot Sport Cup 2 and a huge rear wing, although the new item makes a fifth more downforce than before and works in tandem with a pretty beastly diffuser carried over from the GT4 Clubsport race car. In fact, aero is a significant element of the new Cayman GT4, which can somehow lap the Nürburgring quicker than the Carrera GT ‘super sports car’ did back in 2004. ‘Progress’ hardly does it justice.
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And there’s a different sort of progress in the engine bay: an even better sort. At one point, Porsche toyed with the idea of equipping the Cayman GT4 with a highly tuned version of the downsized 2.0-litre turbo flat-four found in everywhere else in the Cayman range. But in Zuffenhausen, they correctly decided that wasn’t good enough, and so the new car gets an evolution of the 3.0-litre engine found in the current Porsche 911, only with the turbochargers sidelined and the cylinders substantially bored and stroked out. You read that right.
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Understanding the GT4’s new engine
The new 9A2 Evo unit is a 4.0-litre flat six that spins to 8000rpm, making 414bhp and 310lb ft along the way – an improvement of 34bhp over the old GT4, although torque remains the same (in fact, it arrives a touch later, at 5000rpm). It gets a forged steel crank, hydraulic valves and Piezo fuel injectors that improve propagation by making three individual – and presumably obscenely rapid – squirts for each stroke of the piston. Porsche can get the system working at 8000rpm but not at 9000rpm, which is why the 4.0-litre engine in the upcoming new GT3 won’t have it, and elsewhere there are low-friction roller cam followers instead of tappets. Below 3000rpm, this engine can also shut down a bank of cylinders for better fuel economy. Cleverly, it switches banks after a short while to keep the catalytic converters hot and operational.
On the road? We’ll have to wait. Sorry. That said, the suspension is encouragingly well mannered while trundling through the unevenly surfaced paddock at Knockhill, and if the old GT4 is anything to go by, the new car ought to ride just as many other mid-engined machines do: surprisingly, effortlessly well, particularly at the front axle, where the spring rates can be dialled back.
Alas, for now we’re limited to confines of Knockhill Racing Circuit, although given four in five owners will use their GT4 for track days, this is hardly an inappropriate place to get a first taste. It rained at lunchtime but now it’s dry, which is just as well, because if ever there were a circuit to provoke a car with even a morsel of inherent instability, this is it. There’s a looping, ducking sequence at the far side of the circuit that feels as though the car’s centre of gravity as been thrown in a tumble dryer, and even the opening right-hander is a tight, big dipper of a bend that flows over an adversely cambered crest. It’s taken way up into third gear.