When the Porsche Boxster and Cayman became the 718 Boxster and Cayman in 2016, their naturally aspirated flat-sixes were replaced by turbocharged flat-fours. But Porsche Motorsport, the part of the company responsible for 911 GT3s and the like, is committed to naturally aspirated flat-sixes. That's why the 2020 718 Cayman GT4 and Boxster Spyder get a new 4.0-liter six with no turbos in sight.
This pair make their debut today as successors to the much-loved Cayman GT4 and Boxster Spyder of 2015. And unlike before, the Boxster Spyder is now a full-on Motorsport product, which means it shares its chassis with the GT4.
Back to the engine. Despite the fact that it shares its 4.0-liter displacement with the engine in the 911 GT3, GT3 RS and Speedster, the 718's new six is not the same thing. Rather, it's a bored, stroked and de-turbocharged version of the 3.0-liter flat-six used in the new 911.
In an email to Road & Track, Andreas Preuninger, head of GT cars at Porsche, said the engine also gets a new forged crankshaft and pistons, piezo fuel injectors, and an aluminum intake system. The engine is dry-sumped, too, with an a oil pump that's designed to prevent starvation in high-speed cornering. It makes 414 horsepower and 309 lb-ft of torque, with a redline set at 8000 rpm, and for now, the only transmission option is a six-speed manual.
You might be wondering why the 718 GT4 and Spyder didn't get a version of the GT3's flat-six. Preuninger says there's a number of reasons.
First, there are packaging issues that come with repurposing an engine designed for a rear-engine car. The GT3's remote oil reservoir would've been particularly problematic. Then there's cost: Porsche wants these cars to serve as an entry point to its Motorsport products, and if they used a GT3 engine, pricing would be pushed way up. And finally, Porsche wanted to keep these cars in the low-400-hp range to make their abilities more exploitable on the street, and Preuninger told us the GT3 engine "does not react very well to reducing the power."
"A detuned version does not make sense," he said. "Especially considering the packaging restraints."
Chassis wise, these cars are similar in philosophy to the old Cayman GT4, but with new hardware. The front axle comes directly off the 991.2 GT3 while the rear axle is unique to the GT4 and spider. Adaptive dampers are standard, with helper springs out back, and manually adjustable anti-roll bars. Camber, toe and ride height settings are also manually adjustable.
There's a new design for the 20-inch wheels, and and in the pictures here, they're wrapped in Michelin Pilot Sport Cup 2 tires, though Dunlops may be available too. Brake sizes have been increased with new rotors and calipers similar to those used on the 911 GT3. Carbon ceramic rotors, which are 50-percent lighter than the standard cast-iron units, are optional.
Preuninger told us the electric power steering has been tuned to provide better feel, while the ABS, traction control, and stability control systems benefit from things Porsche learned when developing the 911 GT3 RS and GT2 RS.
Both the Cayman and Boxster get a new diffuser with integrated twin tailpipes. The GT4 gets a manually adjustable fixed rear wing, while the Boxster Spyder has an electronically deployable spoiler.
With all these changes, the new 718 Cayman GT4 is 10 seconds quicker around the Nürburgring Nordschleife than its predecessor. That means it should run a 7:30 around the 13-mile circuit, which is about five seconds off a new 911 Carrera S. Not bad for a car you have to shift yourself.
Porsche didn't provide a 'Ring time for the Spyder. It's not what that car is about. When asked why Porsche finally decided to do a full Motorsport Boxster, Preuninger told us "Why not? We have the  Speedster now. The Spyder is its little brother. With 981 GT4, 911 R, Touring and Speedster we have a new GT category, the purists' or driver's car. The Spyder blends in perfectly."
Hard to argue with that logic.
The Spyder gets a double-bubble rear decklid that looks a lot like the Speedster's, and as with all its predecessors, it ditches the power-folding top mechanism to save weight.
Pricing starts at $97,550 for the Boxster Spyder and $100,450 for the Cayman GT4 including a $1250 destination fee. That's around $15,000 more than each of their predecessors, but both are still far cheaper than the nearly $145,000 911 GT3. To say nothing of the $276,000 Speedster. Unlike before, production for these cars won't be limited, and dealer order books are open now with Spring 2020 deliveries targeted.
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