A mid-engine two-seater powered by Porsche’s charismatic 3.8 litre, 385hp flat-six linked to a six-speed manual transmission, the Cayman GT4 clearly captured the hearts and minds of enthusiasts the world over when it was launched in 2015.
Our story from the launch of this car at Portimao Circuit garnered over 53,000 FaceBook likes, the highest ever achieved by a factory stock car on 9tro.com, and nearly 4,000 more than the mighty GT3 RS that bowed in two months later.
However, as good as it is out of the box, the Cayman GT4 does actually have a couple of weak points that were soon pointed out in some more extended road tests, and by a few owners who actually use and enjoy their cars on road and track rather than locking them away as investments.
The most glaring of these is the rather tall first, second, and third gear ratios that do not allow the motor to get on cam quickly enough. This makes the engine feel less snappy than it could be at times given the excellence of its chassis balance. It is something you notice more in road driving than on track where you stay in the upper end of the rev band.
One US tuner simply swaps in a shorter final drive ratio, which is one way of doing things, and a relatively inexpensive fix. However, Shark Werk’s Alex Ross has a philosophy similar to that of Mercedes-Benz founder Karl Benz, who famously said “The best or nothing!”
This is why Alex always shoots for a 100% solution, since 99% falls short of perfection and will leave a nagging doubt in his mind even if most of his customers do not recognise a small issue.
“Although we are 911 specialists we instantly saw the potential of the Cayman GT4,” said Alex. “When I first drove one I realised it was about the size of the 997 GT3 RS, had a similar agility, and made a familiar sound, all of which made me feel at home.”
“I liked it enough to buy it, but it was a slightly bitter-sweet experience for me,” Alex continued. “It was the most refined GT car I have ever owned, but not in a good way. As the 3.8 is not a Mezger engine it lacks the ‘graininess’ I expect of a Porsche GT model, while the drivetrain could be a bit more edgy. This is what set me down the path toward creating a Shark Werks GT4 RS through some old school tuning.”
“The problem with the gear ratios is not actually one of overall gearing, but rather the relationship of each gear ratio to the next as well as its relationship to the engine’s power and torque characteristics,” Alex explained.
“The stock GT4 has a long first gear and its ‘Sport’ auto-blip feature makes it easy and safe for drivers unschooled in the heel-and-toe technique to downshift to first gear for slow turns. But there is a gap between second and third, which allows the motor to fall off cam in some situations, making it frustrating on the mountain roads around here,” he says.
“By lowering third through fifth gears, but leaving first and second stock, you can go 2-1-2 for slow bends like uphill hairpins, and then move across to the 3-4 plane without losing momentum.”
The shorter and more responsive third gear ratio also takes away the need to make the across the gate 3-2 downshift so frequently. Meanwhile third and fourth gears now keep the engine closer to peak torque for better twisty road response.
A joint development project was carried out with Guard Transmission, and the new third, fourth and fifth gears that are 14%, 18% and 16% shorter respectively, provide even gaps between first to fifth gears. Alex admits that he signed off a near US$100,000 investment on tooling these new gearbox internals.
Now here is an interesting twist to the story. Because Alex mainly uses his 2016 Cayman GT4 on the demanding mountain roads I experienced on my drive he has also installed a lower sixth ratio in his car. “This is just me being me,” he explained. “Customers get the same lower third to fifth gear ratio set, but retain the stock sixth for relaxed highway cruising.”
A limited slip differential is a vital part of a Porsche GT model. “A Cayman without a LSD does not use its handling potential effectively,” says Alex. The stock Porsche mechanical limited slip differential has a 22/27-percent locking action on acceleration and over-run.