Competition Car September 1973
THE SPEED TRAPS at the South African Grand Prix earlier this year were measuring the John Player Lotus 72Ds at a shade over 180 mph, but although we too got our itchy hands on a 180 mph Lotus, it was a very different type of car. It was. of course, the well-known and very special GKN Lotus 470 and Competition Car were honoured to be the very first journal to road test the ear in its latest and very quick format. Thanks GKN, it was quite an experience!
The vast GKN-Sankey Group are very well-known in their various aspects, a wide ranging engineering consortium of companies encompassing such firms as Kent Alloys, Vandervell Products, Hardy Spicer and so on. Being one of the biggest suppliers of components of all sorts to the motor trade, the idea of building a special "show-piece" car had the dual purpose of being a mobile GKN publicity-gathering machine and also a test bed for GKN components. And so it was that in 1968 the decision was taken to go ahead and built a rather exotic road car, so successful an exercise when completed that a second project has now been completed - this time a four-wheel-drive Jensen chassised monster, powered with a full NASCAR-type Chrysler engine!
But back to the Lotus. As well as being a presentable show-piece for GKN, the projected show vehicle needed to combine handling, performance and dual suitability for road and track use, and so it was that Lotus Components (as Lotus' then customer racing car factory was known) was contacted to build a rather special version of the Lotus 47 sports-racer. Sharing in common the familiar Europa body shape, the 47 was very much a different machine, being a pure track car. However. in place of the usual racing twin-earn power pack, GKN opted for the 3 1/2-litre light-alloy Rover V8 for its tractability, light weight and useful power coupled with the fact that the engine also used many GKN parts, items like BKL alloys supplied for the cylinder head and block, GKN forgings for the con rods, GKN Screws & Fasteners for the push rods, rocker pad inserts, Birfield pressure relief valve filter, Vandervell bearings and so on.
The engine was accommodated by a special Lotus adaptation of the large box-section chassis to which a tubular rear sub frame was added, making the car some 10 ins longer. This gain in length, together with the flared wheel arches, and sculptured lines turns rather 'bread van' appearance of the Europa shape into a much meaner and altogether more menacing beast.
Suspension follows standard Lotus racing practice with reversed lower wishbones and adjustable single top links at the rear and double wishbones at the front. Armstrong shockers and coil springs are fitted all round. Uprights and wheels are magnesium. Steering is by rack and pinion, while there are discs all round with racing calipers.
Although the car when it first ran in 1969 used the 'cooking' 3 1/2 litre V8, the GKN people decided over a year ago that they had learned enough with the car in this 190 bhp form and that a substantial uprating was needed. And so under the auspices of former Vanwall racing mechanic Norman Birkenshaw at Vandervell Products in Maidenhead, where the GKN Lotus is looked after alongside the meticulously restored original Thinwall Ferrari, the engine was completely transformed.
A power output of around 300 bhp was being sought, and this was achieved by boring the block out 60 thou and fitting 60 thou bigger pistons, a new Engle crankshaft and a raise in compression from 10.5: 1 to 11.5: 1. All the usual polishing was done, a set of special manifolds was fabricated and the whole outfit set off with four lusty big twin-choke Weber 45DCOEs. The result on one of the several dynanometers in Vandervell's Research & Development department was a handy 296 bhp at 6,000 rpm. The big V8, now a full 4.4 litres, will rev safely to 7,500 rpm, but in fact the power curve peaks at 6,000 and thereafter drops off, giving 280 bhp at 7,000 rpm.
Apart from the fitting of new constant velocity driveshafts, few other Changes were made. With 7 1/2 ins x 13 ins mag wheels and racing calipers already fitted, there was no need for any further uprating there. Transmission too remained, a five-speed ZF box from one of the old Lotus 49 Fls, a transmission particularly loathed by Graham Hill who as a GKN consultant winced when he first drove the car on the track and learned that he was to reacquaint himself with this transmission! Nevertheless, it is very much up to the job of the power, and with twin interlocks it's impossible to select the wrong cog. The clutch, however, is a problem, basically because nothing bigger than a twin-plate 7.25 ins GKN Laycock version can be fitted, and even the slightest hint of town driving will cause this to complain bitterly! Weighing barely over l4cwt, the 300 bhp of the GKN Lotus really make for quite a car. We picked the car up on a murky afternoon. Sitting squatly on its fat Goodyears, the metallic dark blue car really looked the part. Eighteen gallons of five-star fuel were pumped in to the twin tanks and then the engine was blipped into a life. A throaty burble sent vibrations ruminating around the close-by Vandervell offices. Norman Birkenshaw carefully explained the gearbox and its five-speed pattern, stressing that the only fashion to select gears was to go right through the box. The four Webers gulped fuel frantically. A quick look at the sky. Oh well. This is a chance of a lifetime.
Besides being a performance show-piece, the GKN 47D has been carefully tailored. Inside the finish is lovely tan leather. Snuggling down in the closely-fitting bucket seat, a flank of instruments, tiny gear knob and equally tiny offset steering wheel face the driver. Rear vision is pretty poor. The rectangular window is there still, but more obscured than ever by the cover on the engine for the bulk of those big Webers.
With its current camshafts, the engine still retains a fair degree of torque, but really all the action happens at 4,000 rpm and above. And so it's a case of blipping the throttle, select second and then get first, clutch out and away. A crowd of anxious expressions disappear as a terrified J.H. travels harshly towards the GKN gate, taking great care not to bottom on their ramp. Then it's right indicator on, a flick of the wrists and away. Phew! This is incredible, gear changes race up and the speedo needle too. With its camrny characteristics, then the engine note transforms from a subdued growl to a thundering roar as the tacho races past 4,000 rpm. Behind the tiny leather-rimmed wheel is a speedometer that reads right up to 180 mph, and this time it's the real thing. With its closely-spaced ratios, speeds in gears go like this: 1st 60 mph, 2nd 98 mph, 3rd 126 mph, 4th 154 mph and 5th 176 mph! Of course, we never got the chance to do a flat-out run, but the ease with which 150 mph comes up defies belief. The car just sits there rock stable, jumping slightly every time it hits a slight deviation in the road surface. Apart from that there's just no sensation of speed.
That's not to say, of course, that there's no sense of acceleration. Put your foot down, listen to the engine note and just get pinned back in your seat. It's an incredible sensation. Wet weather prevented us from checking the times, but the 0-100 mph will easily stop the watches in 10 seconds or so. On the road, it's a great feeling. Burbling along at 4,000 in third (just over the legal limit), you then plunge your right foot down. At 6,500 rpm you change up, and in a jiffy you're in fifth pulling 4,500 rpm and backing off for the traffic a mile ahead!
When we got the aptly-registered GKN 47D it had just come from the British GP where it had been used around the paddock and so on, and the clutch was feeling the signs of this stop-start driving, a fact made painfully clear every time we had to use first from a standing start. Nevertheless the gearbox is a delight to use once the unusual gate pattern is mastered. The steering too is delightfully positive, small movements of the wrists making directional change easy and correction of power slides simple. The brakes are well in keeping with the performance, but with racing pads fitted much caution is needed to ensure that they are warmed up before trying a rapid halt.
With the shockers, anti-roll bars and suspension set up for the track, the 47D displays no sign of roll at all on cornering and with a surfeit of power at all times is beautifully balanced. The penalty, of course, comes in terms of harshness on rough roads, but let's face it, that's not really what this car is all about anyway. In terms of looks the 47D is a stunner. It turns heads everywhere. And not only do those fins on the front corners look aggressive, but they actually help the stability greatly. GKN themselves have had over 170 mph on the clock since they were fitted. Inside comfort is assured by the driving position and the seat itself. There are nice touches, like electric windows, to supply an aura of class, but rather predictably they only work erratically. Still you can't have it all ways. Likewise, the 47 suffers the familiar Lotus Europa problem of drawing in engine fumes with the windows open, so it's a case of roasting and leaving them shut, with only the dashboard-aeroflow vents to keep the temperatures down.
All in all you come to love the performance of such a car in a
few hours. Like the Ford GT40 a few years before, the 47D sets
amazing new standards in road car handling and performance, so
much so that a V12 E-type feels positively lorry-like and slow
afterwards. We were honoured to be chosen to try the 47D in its
latest and ultimate state. We're just wondering whether the
D-suffix stands for Different - or Dramatic!
JUSTIN HALER