Speaking with Automotive News, Porsche chairman Matthias Mueller recently commented on the specifics of the Stuttgart’s new powertrains. Muller commented that the flat fours were a definite on some of the brand’s small models, but that they could end up many other places as well,
“First of all, we will have it in the Boxster and Cayman successor. And then we will see how it works and how successful it is and how the customers will react on that, and then we will take the next decisions.”
Though exact details are still foggy, it can be expected that 2.0 and 2.5 liter variants of the engine are in the works; this much has been confirmed via various reports and leaks. Direct fuel injection will be standard to the design of the new engines, and turbocharging will be optional, though it may become standard as Porsche moves to increase fuel efficiency across the board; Porsche recently announced that almost their entire 911 model range will get forced induction before too long, save for the 911 GT3 RS.
An earlier report also suggested a 1.6 liter flat four, though this prospect has been getting the silent treatment recently. In terms of power, base output should be above 250 horsepower, but specific numbers are unknown. Various sources have quoted Porsche insiders as saying that the engines would max out at an output of 395 horsepower.
Currently, the stock engine on the base Cayman is a 2.7 liter flat six producing 275 horsepower, and the range-topping Cayman GT4 is equipped with a 3.8 liter flat six rated at 385 horsepower. The Boxster is equipped with a 265 horsepower 2.7 liter flat six on the base models, and the higher end Boxer GTS comes with a 3.8 liter flat six rated at 375 horsepower.
The flat four provides for better balancing than its in-line counterparts, and its lower profile provides a much improved center of gravity. Disadvantages include an awkward profile which makes packaging difficult. Another disadvantage is the fact that, due to the firing order of a four cylinder engine, merging two exhaust ports creates an uneven exhaust pulse. Exhaust pipes and headers of unequal lengths have been employed to rectify this, but Subaru has developed an “equal lengths, even pulse spacing” exhaust system in recent years.
Porsche currently offers a 2.0 liter in-line four cylinder in its Macan, but the new generation of flat fours will be the power the first flat four sports cars in quite some time. Porsche designed VW’s air-cooled flat four that was later used in the 914 up until 1975. The last Porsche four cylinder was the 968, which offered an in-line four until its discrimination in 1995.
As far as when the new engines will arrive, both the Boxster and Cayman are undergoing redesign as of now, and the successors are due in mid-2016 for the 2017 model year, along with the new boxer fours.