Back when we were a proper country: Putting a V12 in a Jaguar E-Type

One or two people have been saying of late in the E-type Jaguar is getting long in the tooth and fails to compare with its more recent rivals. This week it celebrates its 10th birthday by shedding what might have been termed its milk teeth and replacing them with a brand new set that will put it well to the fore in sports cars for a good many more years yet. The Series 3 E-type, to give the latest version its full title, looks much like its forebears, but incorporates many XJ6 components in the longer wheelbase previously the preserve of the two-plus-two coupé.

By far the most important feature of the Series 3 is the engine. This is the first completely new design to emanate from the Coventry factory since the start of the immortal XK series of six-cylinder units more than 20 years ago. The new engine is not a replacement for the XK series, which continues in production for the XJ6 and as an option in the E-type. This long-anticipated new power unit is a V12 aluminium engine of 5,343cc with a power output of 272bhp at 5,850rpm.

The engine started life as a five-litre V12 built with a view to Jaguar resuming racing. Unfortunately for the enthusiast this policy was not pursued, though the resultant product could well be seen in circuit events before long. It has a 60º angle between the banks of cylinders and bore and stroke dimensions of 90mm by 70mm. The block and head are aluminium, a point of some initial concern owing to the likely higher noise level over a cast-iron block. Jaguar engineers were more than pleasantly surprised when the installed engine was as quiet as any iron unit. The obvious advantage is the saving in weight over the ferrous block, this being 116lb, and the removal of a hundredweight of metal from the front end was well worth while.

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The very noticeable feature of the V12, compared with all previous Jaguar engines, is the adoption of a single overhead camshaft for each bank of cylinders. The reasons were multiple, for the drive for twin cams would be highly complex and Jaguar were keen to stick to chain drive rather than toothed belts because of the considerable experience they had with them. The other main reason was the adoption of the flat-head combustion chamber, which was developed out of work done with a number of single-cylinder units, and also in experience gained by Mr. Walter Hassan, Director and Chief Engineer — Power Units, Jaguar Cars, the designer of the Coventry Climax racing engine. Cost also played a part in confirming the decision to opt for single cams, as well as a further incidental saving in weight of 22lb per bank of cylinders.

The V12 configuration, with its short piston stroke, allows plenty of scope for high crankshaft speeds and there is obviously considerable potential from the seven-bearing unit. It also lends itself to scaling down should the need arise in future. In the early stages of development, the compression ratio was 10.6 to 1, which worked well on 99 octane petrol. This was subsequently lowered to 10 to 1, and finally 9 to 1, which will cope with 97 octane and is suitable from the exhaust emission viewpoint.

This question of exhaust emission is naturally foremost in motor manufacturers’ minds at present, and particularly in the mind of Jaguar, who have so much of their business in the United States. Efficient fuel atomisation and distribution are important in meeting these requirements and this was one reason for the adoption of the Lucas Opus ignition system. This system, another instance of racing-car design paving the way for improved road cars, is fully transistorised and has no moving parts and, therefore, needs no servicing or adjustment. Consequently, poor timing is eliminated and this constant state of tune is a vital efficient combustion and exhaust. This is the first time that the system has been used in a volume production car.

The V12 has been designed to operate with either conventional carburettors or with fuel injection. Carburettors have been chosen for their better emission control, but work proceeds on fuel injection and the Jaguar engineers say it shows great potential in the long term. Four Zenith 175 CDS carburettors are mounted, two on each side, on a pair of aluminium plenum chambers that open on to manifolds of a length designed to give a ram effect to the mixture and also boost the torque in the middle speed range where it is needed.

While at Jaguar’s factory recently, I was able to have a brief driving session in the Series 3 E-type covering some 60 miles in both manual and automatic versions. The shape is the same as before, but is distinguished by the flared wheel arches, giving a dilated nostril effect. This is necessary to accommodate the wide-rimmed wheels with the Dunlop SP Sport E70 VR15 tyres developed for the XJ6. In addition, the radiator grille has been redesigned and from the back the four exhaust tail pipes, the V12 badge and air extractor on the boot lid give the game away.

The roadster is still offered alongside the lovely two-plus-two coupé, but now shares the same 8ft 9in wheelbase, 9in longer than the old roadster; the overall length is 15ft 4.4in. Another XJ6 feature is the incorporation of anti-dive front suspension geometry for improved roadholding, particularly under braking. The brake system is now of the dual circuit safety variety, with inboard discs at the rear as before, but using ventilated front discs for cooler operation under heavy braking.

Several other modifications and improvements have been made in the Series 3. The engine subframe has been enlarged to take the V12 or the XK as required and also allows the engine to be removed with less difficulty. Another advantage of the new subframe is the improved turning circle, which is now 36ft. The lower bonnet panel has been reshaped to take an 18 gallon petrol tank, which is four gallons more than hitherto. The new grille also allows a greater flow of air into the radiator, which has to cool 36 pints of water. The additional 9in on the roadster wheelbase have been used to increase the door size and also the luggage area behind the two seats; a new and more roomy detachable hardtop is now available. For the V12, a three-silencer exhaust system is installed.

To transmit the power of the V12, manual and automatic boxes are available, the latter being an innovation for the roadster. The automatic is the new Borg-Warner Model 12, replacing the former Model 8. This three-speed unit gives greater manual control as required, with full use of second gear being possible for overtaking. The manual box is the Jaguar 4-speed synchromesh type with a bigger clutch. Final drive is with a Powr-Lok limited slip differential on the V12. Steering is rack and pinion with power assistance similar to that on the XJ6.

Impressions of the car were brief, particularly as there was no opportunity to attend the performance on Warwickshire lanes in the snowy weather of early March. However, I was left with two main sensations: silence and effortless acceleration. The quietness of this engine has been matched by the attention paid to the tuning of the sound of the body and suspension. For five litres of power it is very quiet indeed, which seemed all the more remarkable when the accelerator was depressed and speedometer and rev counter swung smartly across to bring the car up to the legal limit. The performance was matched by the splendid roadholding on the Dunlop radials with their anti-aquaplaning tread pattern, and the Girling brakes, which brought the speed down at a touch. The steering retains enough feel through the new wheel to keep the driver firmly in command of the situation.

Performance with the V12 looks exciting enough for most tastes, with a top speed of 150 mph, and a standing start ¼ mile in 14.5 seconds. Fuel consumption should be in the 13 to 18 mpg bracket according to conditions. Prices of the Series 3 range run from £2,866 (including tax) for the 6-cylinder roadster with manual transmission, to £3,529 for the V12 automatic coupé; higher than before but offering a degree of refinement unattainable at anything like the price anywhere else in the world.