David Hobbs – Jaguar XJ13’s Test Driver

David Hobbs

Hang on – I thought Norman Dewis was the XJ13’s test driver?

Noooo …. a common misconception but, in truth, the legendary Mr Dewis did not participate in all the tests. Contrary to popular belief, there were no “unofficial” tests and the car was driven at all of its outings during active development by David Hobbs. It is believed the car was never taken to Bruntingthorpe or, indeed, any other venues besides MIRA and Silverstone – again, despite claims to the contrary. Hobbs was joined on some of the occasions by Norman Dewis but the latter was entirely absent during the culminating high-speed trials at Silverstone in 1967 where Hobbs was paired with race-driver and former apprentice Richard “Dickie” Attwood.

Four years after the end of the project, the car was driven by Norman Dewis at MIRA to help publicise Jaguar’s forthcoming V12 E-Type but the results of that particular outing are well-documented … here and here

From the outset, Jaguar realised that a car such as the XJ13 called for experienced racing drivers to assist with testing and development. There is evidence that William Heynes (Jaguar’s Chief Engineer) approached Sir Jack Brabham early in 1965 as evidenced by the following letter:

Letter from Jack Brabham to William Heynes conforming his willingness to assist with “high speed testing” of Jaguar’s new sports car. The “new sports car” in 1965 can only have been the XJ13 on which manufacture was about to commence.

In the end, Jaguar called on the services of former Jaguar apprentices David “Hobbo” Hobbs and Richard “Dickie” Attwood. In Lofty England’s own words (as published in the February 1993 edition of “Jaguar Driver” published by the Jaguar Drivers’ Club):

Lofty England of Jaguar
“Lofty” England

“… I strongly doubt if Mike Kimberley who was in charge of the XJ13 project took the car to MIRA for Dewis to test contrary to Sir Williams’ orders, possibly Bill Heynes had not informed Kimberley … we tested the car at MIRA … with David Hobbs driving and then took it to Silverstone where my old friend Jimmy Brown who ran Silverstone ensured there were no watchful eyes. We used David Hobbs for the MIRA tests since he had considerable experience of driving large-engined mid-engined cars in Cam Am races and for the Silverstone tests also used Richard Attwood both ex Jaguar apprentices and very experienced Le Mans Drivers. By the time these tests were made the car was some years old in which time there had been considerable development with tyres, brakes and suspension and to have made the car really competitive a lot of re-design would have been necessary so having learnt a lot the car was “put on ice”.

When we were about to introduce the Series 3 E-Type with V12 engine a short film was being made covering the development of the V12 engine and I was asked by Andrew Whyte to permit the use of the XJ13 to produce the right sort of background noise – that lovely-sounding V12 engine. I agreed on the very clear understanding that no high-speed running would be involved – all that was necessary was to go past the microphone at not more than 100mph using a low gear and high rpm.

I think that Norman Dewis had probably been put out by us using David Hobbs who had gone very quickly at MIRA and decided that he would see how fast he could get round – against my instructions. In doing this he hit one of the posts at the top of the banking which indented the body below the wheel hub line starting at the front of the rear wheel arch and taking a piece out of the rear wheel rim after which the tyre went flat and you know the rest …”

So just who is this David Hobbs?

David “Hobbo” Hobbs

David’s Wikipedia entry reads:

“David Wishart Hobbs (born 9 June 1939 in England) is a British former racing driver. Originally employed as a commentator for the “Speed” Channel, he currently works as a commentator for the NBC Sports Network. In 1969 Hobbs was included in the FIA list of graded drivers, an élite group of 27 drivers who by their achievements were rated the best in the world.”

But there is a bit more to it than that …

David Hobbs’ career began with the Jaguar XK140 Drophead Coupé which was his father’s road car which had been fitted with the “Hobbs Automatic Transmission” – a transmission designed by his father who was a gifted engineer. Hobbs had already raced a Morris Oxford which had also been fitted with the Hobbs Transmission but had his heart set on racing his father’s Jaguar – although, in Hobbs’ own words, .. I can’t say it was a particularly mutual feeling between father and I …“! He did race his father’s XK140 at the Oulton Park Spring Meeting in 1960 where he managed to turn it over on the last lap! Much to David’s chagrin, many people still remember that incident and associate it with their memories of him. David survived unscathed although there was some damage to his dad’s car – which I imagine didn’t go down too well …

David Hobbs’ Jaguar XK140 which was rebodied after its accident by Freddie Owen and sprinted by Owen and Dick Tindell

To make matters worse, when David drove the rather battle-worn car home that day, the bonnet flew open and inflicted further damage to the car destroying what was left of the windscreen. David recounts, ” … after that, Dad was a bit upset and said – well, you shagged it you may as well fix it!”. Hobbs had the car rebuilt and painted in a matt finish. He had, by now, joined Jaguar as an apprentice and so had the contacts and wherewithall to uprate it for racing – starting with some decent racing tyres. He reported that he “borrowed” some disc brakes and, .. borrowed a couple of other things … and ultimately that car was quite quick”.

He said, I ended up with the ‘gold-top’ head with triple carburettor set-up and had some decent wire wheels. I put some anti-tramp rods on the back-axle, took all the interior out (or what was left of it) and got its weight down a bit”. Hobbs goes on to say, I raced like that in 1960 and ended up with four wins of one sort or another. One was a handicap race at Goodwood and other wins at Oulton and Silverstone.”  David had his heart set on the Clubman’s Championship at Silverstone which would give him the chance to drive the big circuit.

In 1961 Hobbs raced a Lotus Elite and he recalls that although I was still working as an apprentice at Jaguar, I took a lot of time off to race much to the disgust of my Supervisor“. He nearly got to drive a Jaguar again at the end of 1961 because he had a call from Mr England who asked if I would like to go to Oulton Park to drive John Coomb’s E-Type. So I rushed up to Oulton and, with a typical Hobbs piece of luck, of all people, Jack Sear’s Ferrari fell off the trailer whilst getting ready for the same race which was a support race for the Grand Prix. So Jack Sears ended up driving the E-Type instead of me – being a close friend of John Coombs and all. They let me drive in practice a bit which went very well – I was very impressed with it.”

David says“Shortly after that I tested at Silverstone with Mike Parr  and Mike McDowell who was Competition Manager at Jaguar then. I tested Cunningham’s E-Type. Cunningham had a rather special E-Type with a flared tail like a D-Type. It was one of his Le Mans cars. Parr tested it and I tested it. That was really the first time I had driven a powerful car. I had a lurid slide going through Abbey. I slid this car from just past the apex – a great long slide with all four wheels locked – ending up at the feet of Mike Parr and Mike McDowell”. Hobbs grinned and said, “Good Afternoon gentlemen.” Unfortunately, Hobbs’ slide flat-spotted all four tyres and they didn’t have any spares. The car was loaded onto a trailer and took it back to Coventry. That was the first time David Hobbs had driven a Jaguar other than a 140 – not the best of starts!

Hobbs married at the end of 1961 and left Jaguar because his apprenticeship had finished. He says, Lofty England put in a good word for me with Peter Berry and I drove his E-Type in 1962 as well as his 3.8 saloon. I drove the saloon in the British Saloon Car Championship as well as a number of GT races”. David goes on to say that Pete Berry’s cars were never the best – “always a day late and a dollar short. We were always a couple of steps behind the competition. The Ferrari GTOs were around then. There’s no doubt about it – the Coombs car and Tommy Sopwith’s car were quicker vehicles and I didn’t have any success in Peter Berry’s car. In fact, in about June he gave up racing and took up flying instead. So that was a bit of a short season!”. 

David remembers his first race in 1962 with Pete Berry’s E-Type as follows:

Our first race was the inaugral Daytona 3-hour. The fore-runner of the 24-hour … That was interesting –  I had never been to America before (certainly places like Daytona were real ‘red-neck’ country)…. Jimmy Clark was there racing for Colin Chapman. Chapman rang up and asked if Clark could drive my Lotus Elise in the same race because it was about the best that was going at the time. So Jimmy and I shared a room – he drove my Elise and I drove Pete Berry’s E-Type … he did very well but I only managed five laps before the fuel pump packed up. Jimmy was leading the class by a minute, minute-and-a-half. He came in for a pit-stop and the bloody thing wouldn’t start. After that, he and I both tested a Ford Galaxy for the Daytona 500.” Hobbs laughs and modestly says that Peter Berry had really built him up – saying he was Saloon Car Champion and all sorts of incredible stories – all of which they took in. We both tested for a Galaxy run by Holman & Moody. We both went quite quick and both turned in laps of about 155 which, at that stage, was the fastest I had ever been in a straight line let alone around a racetrack!”Hobbs recalls, Pole that year was ‘Fireball Roberts’ in a Pontiac at 159. In the end they seemed to have decided that us two limeys weren’t big enough or strong enough to drive their stock-cars”.

Fast-Forward to 1967 and Hobbs’ Encounter with the XJ13

Hobbs competed in a variety of races in the US and the UK before he was summoned by Lofty England of Jaguar in 1967. The following transcript was taken from when Hobbs was interviewed by Philip Turner (former UK “Motor” Sports Editor). This is a previously unknown interview and is published here for the first time.

Hobbs The next time I drove a Jag was some years later … 67. Got a call from Lofty again. Would I like to come to MIRA? About 6 o’clock on Sunday morning. That was the XJ13. The original V12.

Turner Was it a surprise? Did you know about it already?

Hobbs Well I knew about it inasmuch basically they had started it before I left Jaguar in 1962. I mean the thing had been kicking around since then. In fact, when I tested in 1967, I’m not exactly sure of dates and things here, but I got a feeling it had been “under wraps” at that date for about two years. 

Turner Kept under a dust-sheet in Experimental. When I went to ….

Hobbs When they finally decided to run it, it had already been built for some time. At least a year or two and they started to build it when I left in 62. And, I think, wotsisname, Norman Dewis wanted to … but they decided that, to test it, they really outta get a racing driver. Although going round MIRA, really, was particularly tame for a racing driver of course. And we went there four or five days actually. And, the lad in charge, of course was Mike Kimberley. And now your actual Managing Director of Lotus. He was just a lad then. Old Mike. Always tapping his teeth with the end of his pencil and saying, “what is it doing going over the bumps? .. would you say it wants more in or more out?”. And it was pretty basic. I mean it had the Dunlop Racing tyres of five years previously and the old Dunlop disc brakes. Pressed steel D-Type wheels. It had E-Type front suspension – rubber-mounted – polybushes – and it had the E-Type rear suspension.

Beautiful-looking thing. And a helluva engine of course cos that was a four-cam. It really gave a lot of horsepower. It gave about 500 … 525? 

Turner About 500.

Hobbs Yeah. It gave quite a lot of horsepower. It went extremely fast. We went to MIRA about four or five times. Sir William came once .. Mr Heynes used to watch it. Then they made the decision to drive it at Silverstone so they decided to get two drivers – me and Richard Attwood, another Jaguar apprentice. So off we go to Silverstone and I can’t remember the exact times but I think we did round about a 1:36 – 1:35 – 1:36. The lap record at the time was help by Paul Hawkins in his red GT40 – about 32 or 33. So we weren’t all that far off the pace. If you consider it had these old pads, old wheels, old brakes. The suspension flexed far too much of course. And of course it had no attempt at any sort of spoilers on it. Very sleek. It was incredibly quick of course down the straights.

Richard and I gave a job list of things to do. We wanted wider tyres – we wanted modern wide wheels for a start and modern racing tyres. I think those two alone would have seen us down to the lap record. And another … I seem to remember the bias front to rear brakes was poor. It wanted a lot of, you know, a good tidying up. We reckoned it would have been quick. 

They went back to the factory and, at that time, the take-over … and that was the beginning of the decline of Jaguar Cars. Really sad. Along with the whole of Leyland. The whole place just ground down. They had no idea of the innovations – they were all just numbers-men – counters. As far as making cars that people wanted they just didn’t have a clue. 

They put it under a dust sheet and it stayed there. Until Norman Dewis took it to MIRA. He’d always been a little bit piqued that he hadn’t been allowed to drive the car in the first place. Of course he rolled it into a little ball. The one that you see now, of course, is a complete rebuild.

But the car, and there’s no doubt about it, but Jaguar were beset with the same problems – mental problems – then, as they have now. They can’t go to Le Mans unless they could guarantee winning and everybody said so. Clearly, you can never guarantee winning the race. The only way you can get close to it is to go! You can test, and test and test until you are black in the face but you really aren’t going to know just how the car is going to perform You are just going to have to go. To win the race you are going to have to go.

But I really think the car would have been an absolute wow. I mean, at Le Mans, the thing would have had it. Because the GT40 in those days was an iron-block Ford that was only giving about 300 brake horsepower. I mean, this thing gave nearly 200 horsepower more than the GT40. There’s no doubt about it, it wouldn’t have been as quick as the Mark 2s, which of course raced in ’67. But it would have been very fast and, just by updating it, cos I’m sure it had been sitting in the shop for a couple of years – just by updating it.

But they had a problem. You’ve got to use Firestone or Goodyear racing tyres for example … Dunlop weren’t making good racing tyres then … for that type of stuff … 

Turner You did 160? It’s still the record isn’t it?

Hobbs It is. Yes.

Turner Did it feel incredibly quick?

Hobbs It seemed pretty quick. Smoother. 

Turner Acceleration along the straights then braking for the bends? Braking quite hard? Or?

Hobbs Not really, no. 

Turner Was it enough to lift off?

Hobbs It was quite quick.

Turner I’ve been around at 120 but not much more and even that felt fairly fast.

Hobbs Yes – very narrow isn’t it? …. 

Turner So – what did going down the straights feel like?

Hobbs At the straight at Silverstone I would bet we were doing about 150. And, of course, lap speeds of 1:36 is very quick. I don’t know what it is, 1:36? Have to look at a lap chart. A Group C now does about 1:15 .. so … 36 is quite a lot slower.

I think, the way it went, and the way that lap record stood at the time , I think with some mods and if we sat down and made a racing car I think we would have just about cracked 1:30 – probably high 1:20s … 

Turner What was it like aerodynamically?

Hobbs Very fast but no downforce of course. No downforce at all.

Turner Was it lifting at all?

Hobbs Well it probably was but it behaved like a normal racing car of the time. But, there again, the GT40s did have some downforce. They started to have downforce. Well, that was just about the time when people were just starting to tweak downforce. It grew spoilers on the back and stuff like that. The Jaguar was as clean as a whistle. You’d have probably found if you’d put some little Lola-type front spoilers on it and one on the back it would have been absolutely quick around the circuit. To be sure. Malcolm Sayer was the stylist who designed it of course and things like that would have been an anathema to him. The clean bullet-shape was the shape that racing cars were supposed to be and he might have taken a bit of persuading to get any sort of spoiler. Which, in those days, although the word wasn’t applied, was a spoiler…. See the Lola, T70, by then had the big spoiler on the back and a little spoiler on the front…. So I’m sure a little spoiler would have given a big advantage. And they hadn’t even started …

So – it seems this Hobbs is quite a special driver?

Undoubtedly so. Hobbs’ modesty shines through in his interviews but, to find the true story of his many successes, we have to look no further than his career racing history:



INDY 500

What is David Hobbs up to Nowadays?

Hobbs provides commentary for Formula One and GP2 races (alongside Leigh Diffey and former Benetton mechanic Steve Matchett), the SCCA Valvoline runoffs, and parts of the 24 Hours of Daytona. He has also worked for CBS on its Daytona 500 coverage, working as both a color commentator and a feature/pit reporter from 1979 until 1995, and then moved to Speed in 1996 working as a color commentator and then moved to NBC Sports Network in 2013.

David Hobbs appeared in the 1983 comedy film Stroker Ace, playing a TV race announcer. Hobbs appeared in the Cars 2 movie, which premiered in June 2011, as announcer “David Hobbscap”, a 1963 Jaguar from Hobbs’ real life hometown in England.

The words Jaguar, Jaguar XJ13, XJ13 are used in a historical/descriptive context and in no way suggest our recreations/replicas are approved by Jaguar. It is widely known that there was only ever one Jaguar XJ13 and any others can only ever be replicas, facsimilies, tributes, recreations, toolroom copies or similar.

How many quad-cam V12s were built and where are they now?

XJ13 Original Quad-Cam V12

A question often asked of me is,

“How many prototype V12 quad-cam engines were built by Jaguar and where are they now?”

As I reported on this blog back in May 2010, the answer is SIX. Of this six, only three progressed beyond test-bed stage and were installed in cars. A seventh engine was assembled as a 60° V8 and run on Jaguar’s test bed. The V12 block for this engine was converted into a V8 using a special crankshaft with throws for only eight of the twelve cylinders. There were plans to assemble an eighth engine but it never reached the test bed stage.

The above has now been confirmed by XJ13-expert Peter Wilson in an excerpt from his forthcoming book which appears in the November 2011 issue of “Jaguar World”. I can now add further confirmation of these facts from a collection of previously unknown and unpublished original documentation. These documents were in the personal collection of the late Claude Baily – the architect of Jaguar’s quad-cam V12, their legendary XK engine and quad-cam 90° 8 litre V8 amongst others.

XJ13 - Building the Legend
Claude Baily

Claude Baily joined the SS Jaguar drawing office during the second World War and his engineering talents were soon exploited by Jaguar. Baily became intimately involved in Jaguar’s plans to replace their pre-war engine designs with a new generation of engines designed to power their latest saloons. He is perhaps best known for his part in the design of the legendary XK twin-cam engine.

XJ13 - Building the Legend
Claud Baily’s appointment letter.
© Copyright Tony Bailey (WPO Communications) – not to be reproduced without permission.

Spending long war-time nights fire-watching in a small office above the assembly tracks in Coventry, in the company of William Lyons, William Heynes and Walter Hassan, the architecture of the world-beating XK engine was laid down. The new engine was required to reliably provide a minimum of 160bhp, have a long service life and be refined in operation. Before the end of the war, a number of experimental single-cylinder and full engines were evaluated. The following original document from 1941 is likely to relate to one such experimental engine. J.A.Prestwich was better known by its initials “J.A.P.” whose engines were used in many famous motorcycle marques and early aeroplanes. Customers included Morgan, Triumph, Brough Superior, AJS and HRD.

XJ13 - Building the Legend
12th December 1941 – letter to SS Cars referring to experimental engine.
© Copyright image – not to be reproduced without permission.

4, 6, 8 and 12 cylinder configurations were all considered at this very early stage but it was the 4 and 6 cylinder versions that were finally adopted. It has to be said that the BMW 328 engine played an important part in formulating the architecture of these engines. Indeed, Heynes was great friends with an owner of a 328, Leslie Johnson, who loaned his 328 to SS Cars for evaluation.  Johnson was a British racing driver who competed in rallies, hill climbs, sports car races and Grand Prix races. Johnson’s car was highly developed and had raced pre-war. In my opinion, the styling of the XK120 owes much to the BMW. A BMW saloon was also acquired by SS during the war and was fitted with one of the early experimental engines (the “XG”). Walter Hassan used this car as his own personal transport for an extended period for evaluation. One of Jaguar’s own 2.5 litre SS Saloons was also used for testing the prototype engines although most of the development work was carried out on the test bed.

XJ13 - Building the Legend
3.5 litre experimental XK engine – drawing produced to calculate compression ration.
© Copyright image – not to be reproduced without permission.
XJ13 - Building the Legend

Left to right – Walter Hassan, William Heynes, Claude Baily.
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Heynes and Baily applied all their thoughts on engine design to the XK engine although they later commissioned Henry “Harry” Weslake to help optimise their design. Jaguar already had a long association with Weslake, a cylinder head specialist who had been instrumental in modifying the side valve standard engine used in the first SS sports car. He also worked on the larger SS engine. It is believed he was involved in the design of every Jaguar engine up to and including the V12 of the early 1970s.

XJ13 - Building the Legend
Harry Weslake – © Copyright image – not to be reproduced without permission.

The following Weslake report gives a fascinating insight into his evaluation methods and his closing summary bears testament to the soundness of the XK basic design. Weslake concludes:

“…. The engine has stood up remarkably well through these series of tests. The valve gear has remained quiet throughout, there has been no sign of variation in oil pressure and the engine improves in power out-put the longer it runs. The tests have been very severe, particularly the distribution ones, but never once was any mechanical trouble experienced. It is suggested that some breather attachment should be developed in order to keep a small depression in the crankcase so that oil corrosion can be minimised and this would also help to stop oil leaks, particularly in the valve chest covers …”

XJ13 - Building the Legend

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XJ13 - Building the Legend
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XJ13 - Building the Legend
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XJ13 - Building the Legend

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XJ13 - Building the Legend
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XJ13 - Building the Legend
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XJ13 - Building the Legend
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The camshaft drive was by duplex roller chain – an arrangement that was carried forward to the quad-cam V12 prototype engines. This arrangement was used in the first engine installed in the XJ13 as well as the second engine built and tested in a Mk.10 Jaguar. The “genetics” of the XK engine could clearly be seen in the later quad-cam V12. The following page of sketches (made by Claude Baily around 1949/50) clearly show how he was formulating a suitable cam drive for a quad-cam engine. It is believed the sketches were produced as a precursor to designing and building a quad-cam 8-litre 90° V8 engine for a post-war military application. A similar architecture found its way into Baily’s quad-cam V12.

XJ13 - Building the Legend
Baily’s drawings showing his ideas for a quad-cam duplex chain drive
© Copyright image – not to be reproduced without permission.

Claude Baily had been working on a quad-cam 60° since 1949/50 – perhaps earlier. By the February of 1951 a fully-working engine may have been running on the test bed. This 12-cylinder engine was later developed as an 8-cylinder variant for military use. The following quad-cam V12 performance data was recorded on the 19th February 1951.

XJ13 - Building the Legend
Claud Baily’s 1950/51 60° quad-cam 8-litre V12 engine performance data.
© Copyright image – not to be reproduced without permission.

The following picture shows Baily’s data in his own hand. Was this an estimate/conjecture or are they figures actually recorded on the test bed?

XJ13 - Building the Legend
Claud Baily’s 1950/51 notes.
© Copyright image – not to be reproduced without permission.

In 1962, Baily was given the go-ahead to develop his design as a 5 litre V12 to challenge at Le Mans. Although primarily designed for racing, consideration was also given to using the engine in production cars. At least two years before the go-ahead, Baily’s 60° V12 engine was being proposed as a future Jaguar engine with a range of possible capacities as the following memo from Claude Baily to William Heynes demonstrates:

XJ13 - Building the Legend
5th December 1960 memo – “POSSIBLE FUTURE RANGE”.
© Copyright image – not to be reproduced without permission.

The quad-cam V12 engine project was given the code “XJ6” – not to be confused with the saloon of the same name. “XJ6” followed on from “XJ5” which was the code name given to the Mk10 replacement (eventually to become the 420G). Two Mk.10 cars (XJ5/4 and XJ5/5) were to become mules for the production variant of the “XJ6” racing engine. The following memo confirms that six prototype engines were being developed.

XJ13 - Building the Legend

25th November 1964 memo – “12 CYLINDER ENGINES”.
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The first two engines (XJ6/1 & XJ6/2) were first assembled to almost identical specifications which included dry-sump lubrication and Lucas mechanical fuel injection. In April 1966 XJ6/1 was installed in the XJ13. The second engine, XJ6/2, was installed in a Mk10 Jaguar (XJ5/5 – manual gearbox) on 14th April 1965. It was converted to wet-sump lubrication although its Lucas fuel injection system remained. After six months of testing in the Mk.10, XJ6/2 was removed from the car and reunited with a dry sump for further test bed development. In March 1966 it’s dry sump was again converted to enable fitment in a second Mk.10 (XJ5/4 – automatic gearbox). By this time it had acquired a sextet of SU carburettors. It ran for almost 35,000 miles in this car before it was removed and replaced in XJ5/5. It was finally removed from the latter car and placed on the test bed for further development/testing until it was put into store in March of 1969. It remained as a complete engine until I acquired it in 2010. It is now being rebuilt to its original specification and will be placed in my replica of the 1966 XJ13.

So, to answer the question “How many quad-cam V12s were built and where are they now?” SIX quad-cam V12 engines were built.

  • XJ6/1 The first quad-cam V12 built but only the second to leave the test-bed and be installed in a car (XJ4/1).  Damaged in 1967 and retained as a spare by Jaguar. 
  • XJ6/2 The second quad-cam V12 built and the first to be installed in a car (XJ5/5) Survived as a complete engine and sold by Jaguar in the mid 1970s. Currently under restoration to original specification (same build spec as XJ6/1).
  • XJ6/3 Only ever ran on the test bed in a variety of configurations. Has not survived.
  • XJ6/4 Built using cast iron block and ran on test bed. Has not survived.
  • XJ6/5 Internally modified to run as a V8. Ran on test bed for a short while in 1965. Surviving components are with a collector in the US.
  • XJ6/6 No records exist. It is believed this engine was never actually assembled.
  • XJ6/7 Built to trial a die-cast “open-deck” engine block.  Installed in XJ4/1 (XJ13) to replace its original engine when damaged in 1967. Remains in the car to this day.
  • XJ6/8 Built to competition spec with ultimate development of cylinder heads but never left the test bed. Cannibalised whilst in storage in 1969. Cylinder heads placed on XJ6/2 which remain with it until today. The engine block found its way into an XJ13 replica built by Bryam Wingfield for the collector Walter Hill. 

It is interesting to note that Jaguar’s XJ13 currently has a die-cast block that differs from its original XJ6/1. This die-casting process is used to reduce costs and will have been more relevant for a production as opposed to competition engine. The following letter indicates the target casting weight of a V12 block (OXW 5620 is an experimental part number current at the time of quad-cam testing)

XJ13 - Building the Legend
XJ13 - Building the Legend
Die Casting Quote.
© Copyright image – not to be reproduced without permission.

The XJ13’s rather poor power to weight ratio when compared with its likely Le Mans competitors may have contributed to this attempt to lighten its weight?

As Mike Kimberley recorded after a test of the XJ13 at Silverstone in 1967:

BHP per lb weight

  • Ferrari P4/ .210
  • Lola Chev/ .207
  • Ford Mk4/ .206
  • XJ13/ .177

It is also interesting to note that the engine currently installed in the XJ13 has a single OPUS 12 cylinder distributor. Its original engine, XJ6/1, as well as XJ6/2 were fitted with twin 6-cylinder distributors.

XJ13 - Building the Legend

XJ6/2 Original twin distributors as originally fitted to XJ6/1.
© Neville Swales.
XJ13 - Building the Legend
XJ13 single 12-cylinder distributor on XJ6/7 engine.
© Neville Swales.

The rebuilt XJ6/2 will, of course, be built using its original twin distributors. In 1966 Claude Baily was charged with pricing the OPUS system. The following letters give an interesting insight – comparing the various options under consideration.

XJ13 - Building the Legend
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XJ13 - Building the Legend
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XJ13 - Building the Legend
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There are other differences between the XJ13’s original engine (XJ6/1) and the one currently installed in the car (XJ6/7). One is the inlet manifold throttle bodies. The first photo shows the original (1967) arrangement with dual throttle bodies (and separate mounting plates – coloured yellow) and the second shows the current arrangement (photo taken 1973) with individual throttle bodies and a single mounting plate on each head. Note also the different cam cover treatment – the earlier engine has the “trademark” polished cam covers wheras the currently-installed engine has a crackle-black finish.

XJ13 - Building the Legend

1967 (original car)
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XJ13 - Building the Legend
1973 (rebuilt car)
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The words Jaguar, Jaguar XJ13, XJ13 are used in a historical/descriptive context and in no way suggest our recreations/replicas are approved by Jaguar. It is widely known that there was only ever one Jaguar XJ13 and any others can only ever be replicas, facsimilies, tributes, recreations, toolroom copies or similar.