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Mar 21, 2012

Porsche 918 Spyder exclusive


When Porsche first showed us its 918 Spyder concept two years ago, we all struggled to believe what we were being told. Here was a new 200mph supercar which would lap the fearsome Nurburgring in less than seven minutes, 22 seconds, yet could average 94mpg and emit a mere 70g/km. Not only would it be the cleanest petrol- engined plug-in hybrid in the world, it would also be one of the fastest supercars ever created.
Too good to be true? To find out, we visited a Porsche test facility in southern Italy to spend a day with the team tasked with turning the concept into a reality.

It’s immediately clear that significant alterations have been made since the 918 was revealed. For starters, there’s been a complete rethink on the electric motors acting on the front wheels. Instead of two, there’s now a single 80kW motor powering both wheels via a single-speed transfer gearbox.

Another electric motor (rated at 90kW) is sandwiched between the mid-mounted V8 and the seven-speed PDK gearbox (taken from the 911 Turbo then turned 180 degrees and flipped upside down). This spins at the same speed as the engine and doubles as a starter motor, too.

The mid-mounted 570hp 4.6-litre V8 – based on the 3.4-litre in the Porsche RS Spyder LMP2 race car – has direct fuel injection, dry sump lubrication, variable timing for both intake and exhaust cams, a very high compression ratio and a 9,000rpm rev limit.

The exhaust has been redesigned, with gases now exiting via two new ‘top-pipes’ pointing upwards just behind the cockpit. Engineers discovered having two exhaust manifolds hanging off the V8 engine risked cooking the lithium-ion battery.

In total, there are three power units managed by no less than 55 ECUs. Power is a can of worms as you can’t simply add the three power figures together. The front motor is single geared anyway (and becomes redundant beyond 235km/h, or 146mph), so that needs taking into account. But Porsche says that in third gear, peak torque of 880Nm is available at 2,000rpm. That’s a monster amount in anyone’s language.
.autoexpress.co.uk

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