Porsche’s GT model line director Andreas Preuninger calls the 2020 718 Cayman GT4 an evolution of the 981-series model. Technically, he’s right, as there’s much about the new mid-engine GT4 that’s similar to the previous car. But let’s take a look at some of the technical highlights that set it apart—and boost its performance.
The heart of the 718 Cayman GT4 is a specially developed, naturally aspirated 4.0-liter flat-six that develops 414 hp at 7,600 rpm and 309 lb-ft of torque from 5,000 to 6,800 rpm. Based on the 3.0-liter engine from the new 992-series 911, it will rev to 8,000 rpm and features a high-strength forged-steel crankshaft, geometrically optimized connecting rods, and a 2.63-inch-diameter crankshaft main bearing (up from 2.48 inches on the 992-series 911 Carrera S). The composite oil pan is also taken from the 992’s engine and weighs 36.5 percent less than the cast oil pan in the previous GT4.
To enable the engine to rev so freely, the valvetrain features rocker arms with hydraulic valve clearance compensation. For the first time in an engine capable of such high speeds, the centrally positioned injectors of the direct fuel injection system are controlled by piezo units that finely atomize the fuel with a maximum fuel pressure of 2,900 psi. The optimized spray pattern of the piezo injector reduces droplet formation on the cylinder walls and counteracts potential soot formation, reducing fuel consumption and exhaust emissions.
The variable intake system features two resonance valves, which open individually or simultaneously, depending on engine load, and adapt the frequency of the pulsating air column on its way to the valves, depending on engine speed. This improves the fill level in the cylinders and results in better torque characteristics.
On light throttle between 1,600 and 3,000 rpm, the engine management system shuts the fuel supply to one of the cylinder banks, turning the flat-six into an inline-three. At a constant load, the system swaps combustion between the left and right banks every 20 seconds to ensure a uniform flow through the catalytic converters. Apart from a slight change in engine note, the switch is almost imperceptible to the driver.
Standard transmission is a six-speed manual, though the GT4 will also eventually be available with a seven-speed PDK transmission. The shift lever is 0.78 inch shorter than on the standard 718 Cayman. Dynamic transmission mounts minimize the transfer of oscillations and vibrations from the drivetrain to the body and also reduce unwanted movements of the powertrain when it’s driven hard. An auto-blip function automatically matches gearbox and engine speeds during a downshift. This feature can be individually activated or deactivated at the touch of a button on the center console.
The redesigned exhaust system features a large cross-section to reduce exhaust backpressure and increase power. More important, the arched design of the muffler provides the necessary clearance for the rear diffuser’s functional central venturi. The muffler surrounds the diffuser in the shape of a saddle to makes the best use of the limited available space. The elements to each side of the muffler are particulate traps required for the latest European emissions regulations. The particulate traps are not required to meet U.S. emissions regulations, but U.S.-spec cars will still be fitted with the units—minus the actual particulate traps inside—because they act as secondary mufflers.
Here’s why the new exhaust system is so important. Its design allows for a functional diffuser at the rear of the car that accounts for 30 percent of the downforce on the rear axle, with virtually no detrimental effect on drag. The diffuser works in conjunction with the large fixed rear wing and integrated winglets, which alone develop 20 percent more downforce than the setup on the previous GT4. That adds up to an additional 26 pounds of downforce at 124 mph, or 268 pounds of downforce at 188 mph.
The front fascia has been redesigned to reduce lift on the front axle and help maintain the aerodynamic balance of the car. Special bypasses on the outer extremities allow airflow to exit in front of the front wheels to counteract turbulence in the wheel housings and generate downforce on the front axle. The central opening guides the airflow upwards through the center radiator to an outlet in front of the front luggage compartment lid. An additional Gurney flap generates a vacuum that sucks air from the outlet.
The front spoiler lip has also been redesigned and features a recessed GT4 logo. The underside is dimpled like a golf ball so the airflow clings more closely to the surface, reducing drag. NACA ducts in the underbody panel supply cooling air to the engine compartment without increasing drag.
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