Ruf are still turning out stunning Porsche 911 conversions. The SCR 4.2 combines 964 style with 993 suspension and 997 running gear. Photography by Antony Fraser

This burnt orange SCR 4.2 is a very special package, because although it resembles a 964 it’s actually based on a 993, featuring the multi-link rear axle and suspension. ‘We wanted the most modern rear axle found on an air-cooled 911,’ says Marcel Ruf, son of Ruf founder Alois.

It’s not that they then clad the 993 shell in un-guttered 964 panelling – all classic Ruf bodies are smoothed off like that – it’s that the total wheelbase is increased by 7cm. That’s by 2cm on the front axle, and 5cm on the back. The total length of the car stays the same, so it’s the wheelarches that have shifted in the bodyshell by that much in each direction, forward and backwards, and that of course means the distance from bumper to wheelarch is less.

The internal cabin dimensions don’t alter – the extra wheelbase doesn’t gain any more room in the footwells. Those sumptuous bulging wheelarches are hand-beaten and hand-welded, and house five-spoke 19in Ruf alloys, wearing Michelin Pilot Cup 2 tyres, 285/30 back, and 245/35 front. The SCR’s extended wheelbase is only discernible when stood next to a standard 964.

Ruf’s new 525bhp SCR 4.2 Porsche

Ruf believes that the extended wheelbase brings better stability for high-speed driving – ‘the main reason we did this was to have the same wheelbase as a 996 or 997, to give more stability at high speed than the 964 or 993, which can seem a little choppy.’

And there’s a perfectly good reason for that, because of what they’ve done with the SCR’s powertrain. Wait for it: they have installed a liquid-cooled, normally-aspirated 4.2-litre, 525bhp 997 Mezger engine, driving through a six-speed manual transmission...

Put simplistically, they’ve turned an air-cooled 993 into a GT3 kettle, and presented it as a 964. The fundamental reason they didn't add turbos is simply down to space for the radiators – there just isn’t room for intercoolers (though the 2017 Yellowbird is configured to do so).

Ruf’s new 525bhp SCR 4.2 Porsche

The radiators are behind the 964-style front panel and the central air inlet, and in fact the entire water cooling system passes through the car, because there was no other possibility than to use the front panel for the radiators. The central section of the front bumper is an air intake, and the slats in the rear valance dissipate the hot air. It’s all very impressive.

The SCR’s doors, front wings and front lid are in carbonfibre, and the rest of the bodyshell is steel. Whilst the immediate impression is that of a 964-derived car, in the cabin the dash and gauges are the only broad references to that model.

Marcel describes the spec: ‘For the SCR 4.2 we made everything as modern as possible, so for the rear axle we took the 993 multi-link, and in the front we retained the regular MacPherson wishbones as fitted on the 964 or 993, incorporating the package that we’ve developed with Bilstein, with our own springs and shock absorbers that have been spec’d for this car. The six-speed manual gearbox and rear-wheel drive incorporates a very strong differential so the traction goes the right way.

Ruf’s new 525bhp SCR 4.2 Porsche

‘The rest of the car is classic Ruf, with the integrated mirrors, rain gutters deleted, and the integrated rollcage within the cabin, though for most of the interior we have been very restrictive: the cars have no door pockets, just carbonfibre plates; there’s no radio, though we do have air-con, which is a minimum feature that everybody wants today.’

The SCR dash sports typical Ruf instruments, black background with green dials, and the distinctive Ruf steering wheel, aluminium pedals, lightweight carbon door panels with RS-style door pulls and still offers electric windows and mirrors.

At the wheel of the SCR 4.2 there’s a fabulous seating position, the chequer pattern reflected in the shiny carbon door panel. The car feels light and eager on take-off, to the accompaniment of a booming exhaust note. Initially it does feel like the 993 donor – albeit an RS version – and its longer wheelbase is not detectable in a straight line.

It’s a fairly stiff clutch, and I’m quickly reaching top gear in the six-speed ’box thanks to the instant power delivery and lightness. I wind it round to 4500rpm and it really does start to go. Changing gear, the revs drop imperceptively between each shift. It’s a linear power delivery, a vast surge of pace and speed as the car gobbles up the tarmac and the horizon rushes up to meet me and the scenery hurtles by on either side in a blur. It’ll go all the way to 200mph (322kph), given unrestricted Autobahn.

Ruf’s new 525bhp SCR 4.2 Porsche

Its fine handling is enjoyable, and I’m sensing the longer wheelbase in cornering. It's maybe not as intuitive as a 964, though it is totally sure-footed. Small wonder, given the enormity of the tyre package. The SCR is extremely powerful, and I am inclined to liken it to a 997 GT3 RS in that respect.

Does it feel like anything like a 964 or 993? Not surprisingly, there’s an ambiguity about the controls – the dash, gauges and seating posture tell me that that’s what I’m driving, while what I’m feeling are the sensations of controlling and riding in a modern, high-revving 997. Best of both worlds, then. With production levels of around 10 cars a year, the SCR 4.2 costs €430,000.

NEXT: Ruf's all-new 2017 Yellowbird Porsche