The new 4.0-litre flat-six powering the new 718 Cayman GT4 and Boxster Spyder sports cars is a little more special than Porsche is making out. In the press release for the pair, Stuttgart said that the new unit is “based on the same engine family as the turbo engines in the current 911 Carrera model series”.
Really, it’s only loosely based on the 3.0-litre Carrera turbo engine. Speaking to Car Throttle at the Goodwood Festival of Speed, Porsche GT division boss Andreas Preuninger confirmed that other than some of the ancillaries, “hardly anything” is carried over.
“Actually it’s a bespoke new engine - it’s from the 9A2 family and we call it the ‘Evo’,” he said, adding, “We made a new crankcase, new cylinder heads, new pistons, new crankshaft, new rods”.
If you’re thinking that’s quite a lot of work for two relatively low-volume models, you’d be right. That’s because it’s quite likely the 9A2 Evo will go on to power other Porsches.
“It’s a massive effort [to develop the engine],” Preuninger said. “We believe in normally-aspirated engines, especially for cars in that niche - puristic cars. To be frank with you, we can use this engine in the future for other models maybe as well”.
Could that include non-GT Porsches? “We have to see,” Preuninger pondered. That’s not exactly confirmation, but the prospect wasn’t ruled out either. Could the Cayman and Boxster range make a glorious return to atmospheric engines outside of the GT4 and the Spyder? It’s not outside the realms of possibility. The 9A2 Evo - with its petrol particulate filters - is compliant with the latest noise and Euro6 DG-Temp emissions regulations, and thus has a shelf life of a good few years ahead of it.
As for why the Cayman GT4 and Boxster Spyder don’t use the higher-revving flat-six found in the 911 Speedster, that’s down to two main factors: packaging and cost.
“The GT3 engine, you cannot compare it [to the 9A2 Evo] - we can’t use it here…you can make it fit in with a hammer and take sheet metal out, but that’s not fit for mass production”. Installing it in the mid-engined 718s would require flipping it around 180 degrees, a tricky feat given the location of the dry-sump lubrication system’s oil tank.
As a proper motorsport engine (it’s used in the 911 GT3 Cup), it’s also stuffed full of exotic materials, which just aren’t needed for a car like the GT4. “‘You don’t need a titanium conrod set on a car with 414hp,” Preuninger explains.
The 9A2 Evo is much more conventional, fits in with no major modifications, and can be built on the same production line as the standard 9A2 engine. This makes for a less expensive car that can be built for longer and in greater numbers. Even if the 9000rpm-capable unit could have gone in, that £75,348 starting price for the GT4 would have been considerably higher.
Is the new engine any good? We’ll find out when we drive the car for the new N/A 718s for the first time next week.