Speedster announcement underlines Porsche’s commitment to atmospheric engines for GT cars
Nobody is prepared to officially circulate it, but the 991 Speedster’s arrival confirms the rumours that the 992 GT3 will use a version of Porsche’s 4.0-litre naturally aspirated flat six. Like the exclusive 911 R the Speedster borrows its manual six-speed gearbox from, the limited-edition Speedster has some technical developments that are too significant to have just been created for a special low-volume model.
The fact that the GT department has managed to enable the Speedster to pass the Euro 6d TEMP EVAP-ISC emissions standards by fitting a pair of exhaust particulate filters also signals that Porsche GT’s commitment to naturally aspirated engines won’t die with the end of the 991-series 911.
Speaking at the launch of the 911 Speedster, Thomas Mader, project manager of GT road car engines, said: “We got the chance from the board at the start of the (991) GT3 generation to redesign the complete engine. So we decided to do an engine family. And I think, when I’m sitting here, it was absolutely the correct decision to do that.”
Mader admits it’s not been easy to get the engine through the latest emissions standards, but using experience gained from the race engines has helped. The road car gains a development of the RSR’s individual throttle bodies, improving the mix of air and fuel with the benefit of more power, allied to lower emissions. As Mader admits: “We have, I think you say, with one stone, caught two birds.” Power for the Speedster’s engine swells to 510hp at 8,400rpm and 470Nm at 6,250rpm, the engine’s maximum rpm still at 9,000rpm. The fuel pressure in the injection system is increased too, from 200 bar to 250 bar, that improving the spray pattern and aiding combustion.
In another example of engineering alchemy, the GT engineers have managed to add a pair of gasoline particulate filters to the exhaust while actually reducing its overall weight. Using a thinner-walled construction and a new welding process sees the exhaust weigh 10kg less than that of the GT3, despite the addition of those usually weight-increasing filters. Nobody’s saying anything, but the engineering certainly speaks volumes as to future GT car specs.