911 Speedster's New 4.0 N/A Flat-Six To Power Other Porsche Sports Cars

While it’s reasonably accurate to say that the Porsche 911 Speedster uses the 991.2 GT3’s engine, the reality is a little more complicated.

The 4.0-litre, naturally-aspirated unit has been extensively modified before being slotted into the back of Weissach’s latest creation, incorporating a pair of petrol particulate filters. That’s crucial, because it means the Speedster, while being a last hurrah for the 991, won’t be the final chapter for this high-revving wonder. It’s technically possible for it to stick around for a while, and it’s destined to appear in other Porsche sports cars.

The engine is now Euro 6d Temp EVAC-ISC (EU6 DG) compliant. Which, we appreciate, sounds utterly baffling, but it’s reasonably straightforward: cars sold in the EU after September 2019 must be Euro 6d Temp, which means they’re approved according to the WLTP (World Harmonised Light Vehicle Test) and RDE1 (Real-world Driving Emissions) standards, and any new models that comply and are released before January 2020 are good to be sold until January 2021 when RDE2 arrives. TL;Dr - this engine has a decent shelf life in its new guise.

Other alterations to the engine include new high-pressure injectors with an “optimised spray pattern,” new individual throttle bodies that make the 4.0-litre more responsive than ever, and finally a new stainless steel exhaust. It’s quieter to satisfy stricter noise regulations, but the silver lining is it’s 10kg lighter than before.

At the launch of the 911 Speedster in Sardinia this week, 911 Spokesperson Holger Eckhardt explained that Porsche wouldn’t go to all that effort just for one car, before alluding to “spy shots you might have seen.”

This is a fairly hefty hint, we think, that the incoming - but so far unconfirmed - 718 Cayman GT4 and 718 Boxster Spyder models will use the 4.0-litre unit.

Both it and a supposed updated version of the 3.8-litre N/A six used in the older GT4 and Spyder have been rumoured as the chosen powerplant for the cars, but with the larger engine’s new emissions approval sorted, it’s now looking the more likely candidate, albeit with a reduction in power. Plus, with these two cars destined to have a short production run, they’d fit nicely with the emissions regulation timetable outlined further up this page.

As for the 911 Speedster, we’ll let you know what that’s like to drive when the embargo drops next week.