Hubert Burda Media

The Thing About the Porsche Turbocharged Flat-Fours

When Porsche’s 911 Carrera and 911 Carrera S went turbocharged, a large following of pedantic die-hards went berserk. Then came the 718 Boxster, and as one would have guessed, it arrived turbo too. While the naturally aspirated engines are loved for their instant throttle response and wonderfully soulful expressions, the turbos do have their strengths. But how good is it in the case of the 718 Boxster? Dieter Landenberg, deputy director and manager of Porsche’s historical archives, explains.        

Porsche's flat-four engine

Porsche has always been liked for being naturally aspirated. So why did Porsche decide to go turbocharged?

Our aim was to increase power and performance while at the same time, reducing fuel consumption. Gaining more power from a naturally aspirated engine involves more displacement, and therefore higher standard consumption. Even though Porsche is continuing to develop naturally aspirated engines, we believe turbo engines are the most effective at enhancing performance, reducing fuel consumption, delivering an emotional appeal and ensuring day-to-day usability. That is also why Porsche can now look back on a long history of turbo engines. We have been successfully using 911 turbo engines in the line’s top model since 1974.

Is this flat-four derivation of the flat-six engine from the 911 a way to fill the void created by the departure of the old Boxster’s flat-six? 

Yes, the four-cylinder turbo boxer engines has replaced the six-cylinder boxer engines
from the Boxster (type 981). The 2.7-litre naturally aspirated boxer engine has been replaced by a 2.0-litre boxer turbo engine, and the 3.4-litre naturally aspirated boxer engine by a 2.5-litre boxer turbo engine.

By lopping two cylinders off the six, how do you ensure the new flat-four live up to Porsche’s image?

The new flat-four continues the tradition of Porsche’s four-cylinder flat engines in its 718 mid-engine sports cars. In the 1950s and 1960s, these cars won numerous races, including the legendary Targa Florio and the 24 Hours of Le Mans. In the new 718 models, Porsche is introducing two completely new four-cylinder flat engines with turbocharging. Their power and efficiency have been increased significantly compared to the previous engines. A bundle of innovations also ensures typical Porsche driving pleasure. The engines excel with more spontaneous response, free-revving properties up into the highest rpm ranges, and last but not least, their passionate sound.

integrated charge-air cooling system

What’s the difference between using an air-to-liquid intercooler and air-to-air intercooler?

An integrated (air-to-liquid) charge-air cooling system with a separate low temperature circuit provides the demanding performance figures despite very limited space. Thanks to the circuit’s “inertial mass”, the indirect charge-air cooling system can keep the intake air temperature at a low level for longer when adopting a dynamic driving style. What’s more, indirect charge-air cooling makes it possible to retain the Boxster-typical vehicle characteristics such as the mid-engine layout, luggage compartment volume and, of course, the unique styling. Direct charge-air cooling offers advantages in terms of weight — which is particularly important with a rear engine — delivers benefits at high speeds, and is particularly well-suited to the 911 thanks to the vehicle’s design.

Why are twin turbochargers not used for the flat-fours as compared to the flat-six?

The bi-turbo layout could not be used in the current 718 for space reasons, and also has implications in terms of performance due to the ignition sequence specific to the four-cylinder boxer.

Some people claim the new 718 sounds like a Subaru. What have you got to say to that?

The 718 produces a sound that is characteristic of a four-cylinder boxer engine, and we are very proud of that at Porsche. No other four-cylinder engines deliver a comparable sound.