The heart of the new 718 GTS 4.0 models is their naturally aspirated four-litre six-cylinder boxer engine. With an output of 294 kW (400 PS), it has 37 kW (50 PS) more than the four-cylinder turbocharged S models and impresses with its particularly direct response characteristics and linear power delivery. The powertrain of the new GTS model is essentially equivalent to that of the 718 Cayman GT4 and 718 Spyder. The boxer engine is based on the same engine family as the engines in the current 911 Carrera model range. The electronics only limit its high-revving potential to 7,800 rpm, with maximum power available at 7,000 rpm. Its maximum torque of 420 newton metres is constant between 5,000 and 6,500 rpm. Power is transmitted by a six-speed manual gearbox with a dynamic throttle blip function in Sport mode.
This results in impressive performance figures. Both 718 GTS 4.0 models reach a maximum speed of 293 km/h. In the 0-100 km/h sprint, the six-speed manual 718 GTS 4.0 is one-tenth faster than the turbocharged S model, hitting 100 km/h in 4.5 seconds. Acceleration from 0-200 km/h takes 14.1 seconds.
The six-cylinder boxer of the new 718 GTS 4.0 two-seater is a high-performance, high-revving engine that also excels through exceptional efficiency. It benefits from technology and numerous developments that also reduce fuel consumption and exhaust emissions in the 718 Spyder and 718 Cayman GT4, such as adaptive cylinder control. Between 1,600 and 2,500 rpm, and with a load demand of up to a maximum torque of 100 Nm, it temporarily interrupts the injection process of one of the two cylinder banks. The six-cylinder engine then temporarily operates in three-cylinder mode. With a constant load, the cylinder bank is changed every 20 seconds to ensure a uniform load and flow through the catalytic converters. With the exception of a slightly different sound pattern, the system switching on and off is imperceptible to the driver. The effect, however, is clearly evident: the adaptive cylinder control reduces CO2 emissions by up to 11 grams per kilometre. The function can be deactivated together with the start/stop function.
Direct fuel injection with piezo injectors
The formation of the air-fuel mixture in the combustion chambers satisfies particular requirements. For the first time in a high-revving engine, piezo elements control direct fuel injection (DFI). They open the centrally positioned injectors by expanding when a control voltage is applied. When there is no current flowing, the crystals contract and the injection valves close again. This allows the injection process to be divided precisely into different phases, making combustion even more exact. The fuel, finely atomised with a maximum fuel pressure of 200 bar, produces an optimised spray pattern that reduces droplet formation on the cylinder walls and counteracts potential soot formation. The effect: fuel consumption and exhaust emissions drop, while the efficiency of the six-cylinder engine increases.
The variable intake system supports rapid gas exchange in the combustion chambers. It features two resonance flaps, which open individually or simultaneously depending on the power requirement and therefore adapt the frequency of the pulsating air column to the engine speed on its way to the intake valve. This improves the charge level in the cylinders and results in more impressive torque characteristics.
Reliable high-rev concept
The high-revving concept of the naturally aspirated six-cylinder engine is based on intensively enhanced technologies for the four-litre boxer engine. Mechanically, the following components provide the basis for withstanding the peak pressures in the cylinders: a rigid forged crankshaft made of a high-strength steel alloy with deliberately wide connecting rod bearings, geometrically optimised piston rods and a generously dimensioned crankshaft main bearing with a diameter of 67 millimetres. The integrated dry sump lubrication serves the same purpose, enabling optimum oil supply to the engine even at high longitudinal and lateral accelerations. With its integrated centrifuge, the vane-type suction pump separates the oil from the air. A fine oil separator also reduces emissions and lubricant consumption. The robust plastic oil sump weighs 36.5 percent less than a similar cast part.
In view of the high engine speed, rocker arms with hydraulic valve clearance compensation are responsible for operating the valves. The electronic engine management system adjusts the timing of the four VarioCam camshafts according to the load requirement, engine speed and temperature range, for example over an adjustment range of 30 crankshaft degrees on the exhaust side. The effect is outstanding drivability as well as high power output and torque values across the entire engine speed range.
Sports exhaust system with gasoline particle filter
The 718 GTS 4.0 models adopt the sports exhaust system with separated tailpipes from the 718 Cayman GT4 and 718 Spyder. Its design and large cross-section reduce the exhaust back pressure and have a positive effect on performance. A striking detail is the arch-shaped saddle construction of the main silencer, which is now centrally located. The distinctive sound of the free-breathing boxer engine is retained thanks to the damper control, especially at high revs. Fully variable and controlled by engine characteristics, it accentuates the emotive driving experience, depending on engine temperature and load demand, with a charismatic aural backdrop.
At the same time, the sports exhaust system enables the use of a gasoline particulate filter (GPF). In combination with the adaptive cylinder control, the piezo injectors of the high-pressure direct petrol injection system and the start/stop function, it makes an important contribution to compliance with the Euro 6d-Temp emissions standard. Two lambda sensors control the exhaust gas composition individually for each cylinder side via a broadband lambda control system. One additional sensor in each case monitors the conversion of pollutants in each of the catalytic converters. The necessary regeneration process of the GPF happens automatically and without the driver noticing.
Six-speed manual transmission with dual-mass flywheel as standard
The manual six-speed transmission transmits the power of the six-cylinder naturally aspirated engine to the rear wheels. The dynamic throttle blip function improves vehicle stability during downshifts and reduces wear. Powertrain movements that can affect driving dynamics are damped by the dynamic PADM (Porsche Active Drive Mounts) transmission mounts, which minimise the vibrations transmitted. The 718 GTS 4.0 models use the dual-mass flywheel from the 911 GT3.
