“The new engines were not supposed to lose more than 5% of the peak power from 6,500 RPM to 7,500 RPM. “Calibrating and designing the turbocharger to offer good response and low end torque while also delivering high power at 6,500 RPM was the crucial target,” said Baumann. Yet Porsche engineers were able to spin it to 7,500 RPM without a significant drop in output. One of the most important design goals with the new turbocharged flat-4 engines was to preserve the high-revving nature that Porsche motors are known for (turbocharged engines typically prefer to stay on the low end of the tachometer, feeling lethargic as revolutions increase). (For those keeping score, the twin-turbo 3.0-liter in the 911 generates 370 horsepower or 420 horsepower, in the 911 and 911 S, respectively.) It boasts 350 horsepower and 310 pound-feet of torque. The Boxster S and Cayman S arrive with the larger 2.5-liter engine with upgraded variable turbine geometry (VTG), which is technology shared with the marque’s flagship 911 Turbo. The 911's flat-6 and flat-4 engines share the same alloy in the block, the same main bearings, fuel injectors, vacuum pump, connecting rods, fuel pump, piston rings, timing chain, alternator, and air conditioning compressor - just to name a few commonalities.īase turbocharged 2.0-liter engines, in the Boxster and Cayman, are rated at 300 horsepower and 280 pound-feet of torque. Standard models are fitted with a 2.0-liter flat-4 that shares its 91-millimeter bore and 76.4-millimeter stroke with the 911's 3.0-liter flat-six, while S models are fitted with a 2.5-liter flat-4 that has a slightly larger 102-millimeter bore. The all-aluminum engine is offered in the new 718 Boxster and 718 Cayman models in two different displacements. So, Porsche did the logical thing and lopped two cylinders and a turbocharger off the 3.0-liter six to create a 2.0-liter flat-4, with a single turbocharger. “To bring a naturally aspirated flat-six engine to the performance levels of the turbocharged flat-fours would have meant having to increase the displacement significantly, which would have had a detrimental effect on the efficiency of the car.” “A flat-six twin-turbo engine would not have fit in the available room in the engine bay of the 718,” explains Markus Baumann, Porsche’s Manager for Boxer engine development. The advanced engine was earmarked to power future 911 models, but the celebrated new 3.0-liter flat-6 and its forced induction plumbing would not find a home in the Boxster and Cayman.
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