Currently reading: A Rover SD1 with a difference, 10 March 1979 - Throwback Thursday
The Rover SD1 already had a 3.5-litre V8, but for less than £1000 owners could add a set of turbochargers - and the results were fast

By the standards of the time, the aluminium 3.5-litre V8 in the front of the Rover SD1 was quiet, smooth, fast and flexible.

So did the five-seat hatchback really need extra oompf? Tuning specialist Janspeed certainly thought so: for a cost of £960 (excluding fitting) the Salisbury-based company would add two turbochargers, providing 30% increases in power and torque, even more flexibility and a BMW and Jaguar-worrying 140mph top speed.

The Rover 3500 V8 SD1 Janspeed Turbo conversion’s party piece was described by Autocar road tester John Miles in a 1979 test: “Bring the speed of the Janspeed Rover down in fifth gear to under 10mph (350rpm). Then floor the throttle. A little above 10mph the slight shudder gives way to a totally smooth and ever-gathering pull from there to around twice the legal speed limit. A V12 Jaguar owner might not be impressed but the rest will be.”

According to Janspeed proprietor Jan Odor, the conversion didn’t require any modifications to the engine itself. The standard carburettors, air cleaner and air inlet temperature control valve were all retained, with a pair of US-derived Rotomaster Turbosonic units, one to each bank of cylinders, bolted on.

The standard car had an official 0-60mph time of 8.4sec; Autocar’s test equipment measured 8.2sec on the Rover 3500 V8 SD1 Janspeed Turbo.

Although that wasn’t the most dramatic of improvements, it was only part of the story. “It has an incredibly smooth transition on to boost at 1700rpm on full throttle, and unboosted part-throttle performance virtually equal to the standard car,” described Miles. “Use full throttle, keep the engine above 3000rpm and it cuts the standard car’s acceleration times to ribbons.”

When it came to taking the figures at the test track, teeming rain limited the speeds attainable in safety to just over 110mph. Using a suggested rev limit of 5500rpm, Miles calculated that a top speed of 146mph was possible.

Although the engine modifications drew praise, other modifications to the SD1 were less well received.

“Odor had decided, in the interests of on-limit handling predictability, to change the SD1’s hydraulic strut/coil spring self-levelling rear suspension to the straight coil springs from the Rover 2300,” wrote Miles.

“Whether a Rover Turbo owner will want to charge through corners to take advantage of such a set-up is another matter. Likewise, stiff Koni front and Schreider rear dampers felt misplaced.

“But perhaps most incompatible of all to steering and chassis character were the 205/60VR-14 Dunlop Sport Super tyres mounted on 7in wide alloy rims.

“The terrible weather suggested that they might provide some extra traction. They probably did, but together with the suspension settings their stiff sidewalls made the car nervous and over-responsive to the steering and board-like to ride in over poor surfaces.


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“I needed more suspension movement and taller tyres to give a less sharp ride and steering response.”

Miles was also less enthusiastic about the (optional) ‘Turbo’ stickers. Nevertheless, he concluded that “the Rover Turbo impressed us all by being the most civilised performer where it matters – in the engine’s mid-range”.

Previous Throwback Thursdays

14 December 1895 - America's first car race

28 December 1895 - Early British car exports

4 November 1978 - Fiat 131 Abarth rally car road test

15 March 1986 - Renault builds a Porsche rival

2 April 1986 - Figuring the MG Metro 6R4 rally car

26 April 1986 - Rover's sleek CCV concept

18 October 1989 - VW's vision of a 21st century Golf

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bowsersheepdog 7 April 2016

Rubbered up the wrong way

The SD1 is one of the truly great classic British cars, and it's a delight whenever one sees an example on the road, albeit rarer these days than one would like. Looking at the tyre size quoted, there is another case of what I have posted about many times. The tyre sizes on modern cars is symptomatic of where the motor industry is going wrong. Cars are being made too expensive and complicated. It's okay for Porsches and Ferraris and Paganis and their ilk, they will never reach the bargain basement end of the market, but for mainstream manufacturers they must have more awareness of the later stages of their products lives. If replacement tyres, and other parts too, are a prohibitive cost for a fourth or fifth owner, we will end up with a fleet of vehicles with plenty of serviceable life in them but no buyers willing to take them on. Even the likes of old S Class Mercedes and 7 Series BMWs are in the sub-£2500 market of today, but too soon will come the day when even ordinary family cars such as Insignias, Passats, Mondeos and Mazda 6s will become untouchables for banger buyers, due to the cost of consumables like tyres. It's a far greater environmental threat than fuel consumption.
Citytiger 5 March 2016

Very interesting

it just shows how times have changed, this V8 twin turbo would be thoroughly embarrassed by any decent hot hatch. It also shows how tyre choice has moved on, 205/60/14, not many runabouts ride on tyres as small as 14's these days, and I dont think anyone uses 60 profile any more even on SUV's. However we do complain about the ride of a fair amount of modern vehicles being to harsh, I wonder why..
Andrew 61 3 March 2016

Janspeed and then Turbo

Janspeed and then Turbo Technics did some interesting conversions at the time. This sounds like a standard compression ratio was used along with low boost pressure to create a low lag unit. An idea manufacturers tried themselves later.