Supercharged Porsche 911 by Theon Design 2023 review

Back in 1975, Porsche used turbocharging to elevate the 911 from a sports car into a supercar. Today, apart from the low-volume GT3 models, every 911 has a turbo. 

Porsche might have embraced forced induction, but in six decades it has never supercharged the 911.

Step forward Oxfordshire’s Theon Design. Its new 964-based project was born of a desire to be different, explains company co-founder Adam Hawley. “Still, we didn’t realise how challenging building a supercharged 911 would be.” 

‘Grand touring ability’

There were practical reasons for going the supercharged route, too. “The customer requested a car that combined classic Porsche driving dynamics with real grand touring ability,” continues Hawley. “We didn’t want the slam-you-in-the-back Turbo effect. Driveability was key.”

In simple terms, a turbocharger harnesses the flow of exhaust gases to force-feed air back into the engine. The downsides can be tardier throttle response (‘turbo lag’) and a stifled soundtrack. A supercharger is driven directly off the engine’s crankshaft, making it less efficient but quicker to react. Oh, and they also make a great noise.

Studious readers will recall that we drove Theon Design’s ‘CHI001’ 911 last year, which developed 400hp from a 4.0-litre naturally aspirated flat-six.

This new ‘BEL001’ commission (so-named because its soon-to-be owner lives in Belgium; CHI001 was bound for Chile) can muster the same output from only 3.6 litres. However, as we’ll see, it’s the temperament of those 400 horses that really sets these two Porsches apart.

Old-school cool

To Joe Public, this bespoke restomod simply looks like a nice classic 911, but those in the know will clock the swollen wheelarches, deep-dished Fikse alloys and millimetre-perfect stance. Its steel body (carbon fibre is an option, saving 110kg) is painted a custom colour inspired by Porsche 356 Fjord Green. From 991 Speedster-style mirrors to subtle ‘ghost stripes’ on the sills, the details are exquisite. 

Unlatch the rear lid and a Rotrex centrifugal supercharger takes centre-stage in a decluttered engine bay. A water-methanol injection system boosts the fuel octane level (using super unleaded) from 98 to 110 RON beyond 4,500rpm. Twin charge coolers also mean there’s no need for the top-mounted intercooler and giant ‘tea tray’ spoiler of a 964 Turbo, helping preserve the car’s clean and classic look. 

BEL001’s interior is also reassuringly old-school, with haphazard 911 ergonomics, analogue dials and no glaring touchscreens. Look closer, though, and you realise the plastic switches have been remade in milled aluminium, while the Porsche ‘tombstone’ seats, now swathed in lush caramel leather, are reshaped for more support. 

Smooth operator

There’s a neatly concealed Bluetooth audio system, too, but I was quite satisfied with the sound of the air-cooled six: a mechanical snarl augmented by the subtle whine of the supercharger and angry hisses of expelled air.

With just 1,265kg to shift (a new 992 Carrera weighs 1,505kg), acceleration feels effortless, a smooth, soaring rush to the redline that’s the antithesis of the wham-bam old 911 Turbo. 

Like CHI001, this car rides on five-stage Tractive adaptive dampers, but here the settings are softer. On tightly coiled lanes in the Cotswolds, it breathes with the road, feeling supple yet sure-footed – and joyously compact compared to any 21st century supercar. Its hydraulic power steering babbles with constant feedback, while the rebuilt five-speed manual ’box is Teflon-slick. All that supercharged torque means you never want for a sixth ratio, either.

Trans-Europe express

For all its enhanced ability, this is still a 911 you could drive every day, just as Porsche always intended. I’m told its owner has some trans-European road trips planned, which sounds very enviable indeed.

If you want to follow in his tyre tracks, Theon Design can build you something supercharged, including the cost of a donor 964, for around £500,000.

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