Porsche 991 hybrid test drive
The internal combustion engine doesn’t realise it’s there,” says Chuck Moreland, owner of Elephant Racing. You might know the company – it’s a specialist in Porsche suspension – but here Moreland’s talking about the flat six in an early 991.1 3.4-litre Carrera.
Specifically, he’s talking about the Vonnen Shadow Drive, Vonnen an Elephant Racing offshoot that’s developed a hybrid 911 before Porsche itself. If it was going to be done anywhere outside Weissach, then it’s hardly surprising it was here.
Vonnen is in California, specifically Silicon Valley, the absolute global heart of innovation and technology. Moreland explains how it happened: “It was a case of us sitting around talking among ourselves and thinking, ‘hey, wouldn’t it be great if…’. And then we started exploring different ideas of how you might hybridise an existing 911 platform.”
That was three years ago. Today we’re standing around an engine and gearbox, looking at the axial flux electric motor that Vonnen has developed with a European supplier, sandwiching it between the two.
If that sounds familiar, it’s exactly what Porsche will do with the 992 to hybridise it, only it’s left space inside the gearbox to do so. With the 991 there’s no such luxury, so Vonnen had to get clever with the space it had.
It’s been a quick development cycle, especially considering this wasn’t Vonnen’s first solution. Initially Vonnen tried pushing electrically generated drive back into the gearbox via the front-axle output shaft on a 996 Carrera 4.
Moreland says: “That was more a proof of concept, but we learned a lot from it, and we recognised that there was real opportunity for improving. The biggest issue was that the torque was being added on the output shaft of the transaxle, so we weren’t taking advantage of the gear-reduction capabilities from the gearbox.”
Buoyed by the potential, Moreland went all in, saying: “Okay, cost be damned, what if we wanted to make this thing rip? What would we do?” And so we went back to the drawing board and this is what we dreamed up, and it basically addressed all the issues that existed with this car. And that’s how we got where we are.”
Squeezing an electric motor between the engine and transmission adds 26mm in length. That’s required some modification of the structure fore of the gearbox to allow clearance, the electric motor replacing the flywheel, as well as the starter motor, and taking over all the functionality of it, including stop-start, if fitted. The batteries powering it are situated in the luggage area, robbing it of some space.
For the full Porsche 991 hybrid test drive, pick up your copy of Total 911 issue 180 in shops now or get it delivered to your door via here. You can also download a digital copy with high definition bonus galleries to any Apple or Android device.