On this day : Jaguar V12 engine makes its debut (1971)

On this day in 1971, Jaguar unveiled its new V12 engine under the bonnet of the E-type Series 3, with the XJ12 and Daimler Double-Six following in 1972, and the Daily Mirror shared the juicy details.


The new world-beater from Browns Lane

Jaguar E-type Series 3

By Clifford Webb

Jaguar, British Leyland’s prestige car sales contender, yesterday unveiled its long awaited new 12-cylinder engine. By so doing, it became the first car manufacturer to introduce such a complex engine for volume production.

By relieving pressure on the existing six cylinder line at its Coventry plant it will be able to divert a substantial number of these older engines for use in its much sought after XJ6 saloon.

British Leyland has spent £3m on laying down new production facilities for the V12 engine. A great emphasis has been laid on automation. Despite its complexity the new engine will require only one third of the labour which goes into the six cylinder.

The installation is geared to produce 1000 power units a week on two shift manning. The initial production target is only 170 a week on single shift working, and for the time being this entire output is going into E-type sports cars destined for the North American market.

Jaguar XJ12 engine, which followed on in 1972
Jaguar XJ12 engine, which followed on in 1972

The remarkable success of the XJ6, deliveries are still lagging up to 18 months behind orders, has confounded the critics. It is this continuing high level of demand which has clearly led to the decision to use the V12 as an alternative power unit in the E type only, at least at this time.

It is also obvious however that with capacity for 1000 V12s a week it will not be long before a version of the XJ6 also appears with the new engine. In the past two years Jaguar has produced some 8000 E-types annually.

This year it plans to build 4500 of the new V12 E-types backed by an as-yet unknown quantity of six cylinder E-types, unknown that is because until it has tested market reaction to a V12 costing only £250 more than the smaller engine model it does not know if there will be any continuing demand for the older unit.

Jaguar E-type Series 3 engine

Keith Adams
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32 Comments

  1. Apparently even after they officially dropped the DOHC V12 work still persisted with a modestly-tuned road-going DOHC 48v V12 putting out 400bhp while a race version of the DOHC 48v V12 put out 627bhp with potential for more according to one Jaguar engineer.

      • The info in question was found in the Jagweb article – Big V12s & Special Versions, here is the full excerpt.

        “Jaguar produced some prototype 4 valve V12s in the early 1970s. A fast road tune version produced about 400 b.h.p. and a race tune version 627 b.h.p. which was quite impressive for the time, but has since been matched and often exceeded by well developed 2 valve engines. Jaguar never proceeded with the 4 valve V12 because the market simply did not warrant the extra complication although one of these engines was updated to grace the engine bay of the prototype XJ220.”

    • I suppose as the XJ40 AJ6 in 2.9 litre single cam form used the same head as the V12HE, the head from the twin cam AJ6 would fit a V12 (well at least 1 side) so a V12 quad cam was a viable option.

      • There was also Harry Mundy’s experimental 6.4-litre V12, however do not recall reading it featuring such updates.

        While the six-cylinder spin-off of the V12 was intended to be a slant-six, could a related V6 while less than ideal for Jaguar’s needs have instead been used in place of the PE166 as well as in other models (e.g. Range Rover, etc) lacking a six?

        • Was thinking along these lines: as discussed earlier under the article on PE166, from a broader BL-perspective such a 2.673 cc (2.5-3.0L) V6 could have been very useful in the last quarter of 20th century and apparently could have been produced in sufficient numbers (even without the possibility of a third shift to raise maximum production to 150.000 V6/V12 units a year for use in Jaguars/Rovers/Triumps and possibly MGs). Could have made a nice complement to Triumph Slant 4/V8 engines (for use in Triumph/Rover/Jaguar/MG models), together eliminating the need to develop O-/M-/T-series and/or PE166, as well as freeing up development and production capacity for a very useful earlier K-series small engine.

          • Sorry: 1.000 units per week on a two shift basis makes max 75.000 units in three shifts (not 150.000)

          • Concerning both the Jaguar V12 / hypothetical Six and Triumph Slant Four/Stag V8 engines, was contemplating if there was any potential for synergies between the two if such a thing was considered?

            An earlier scenario where Jaguar and Triumph were under the same combine, depending how far along in development their respective designs were during the 1960s could have opened up a different alternative for Jaguar in place of the 60-degree V8 and in turn for Triumph with their problematic V8.

            IIRC the Triumph engine family was designed as a Slant Four/V8 displacing 1.25-4-litres, the Jaguar V12 at least in its earlier form originally displaced 5-litre during development before eventually being capable of growing up to 7-litres via Lister with Harry Mundy achieving an experimental 6.4-litres equating to a V6 capable of around 2.5-3.2-litres.

            Taking Jaguar’s desire for a Slant Six in account (with them not wanting to retreat from the Six cylinder segment) and the likelihood of it acting as a barrier to Triumph’s desire to push upmarket, it would be fascinating to see how the things could be grudgingly resolved between both marques without creating a situation where Jaguar seeks to undermine Triumph’s aspirations (like for example proposing the latter re-enter the FWD segment, etc).

  2. 1000 V12s a week? With the summer break that’s still near 50,000 a year, a ridiculous number. Did Jaguar even produce that many vehicles at the time?

    • Of V12s yes, but this production facility was conceived with the intention that it would also build a V8, S6 and S4 as well for the XJ and the then planned GT(XJ-S), reskinned E type and small Jaguar saloon.

      These of course never happened, the V8 was never bottomed out and when the AJ6 arrived whilst it was essentially half a V12 (single cam used the same head), progress in engineering and production technology and technics meant it required a new line to build it.

      • Was aware a four-cylinder was a distant possibility in light of their other exotic and costly or less than ideal alternatives for their Jaguar Junior saloon, yet was that actually something Jaguar were seriously considering even if it was at most a paper project unlike the V8?

        • It was penciled in under BMH but after what became the XJ-C, the proposed E Type reskin and the GT that became the XJ-S, but was killed when Leyland took over as it was going to be a direct competitor with the Rover P6 and Triumph 2000. It was however probably unaffordable as it would have required a new factory to be built in viable quantity, and Lyons would not have allowed it to be built at a BMC factory or even a factory outside Coventry, having refused Governments offers to do a “Linwood” before.

          • In a hypothetical Triumph-Jaguar combine, the Triumph 2000 or it’s successor could have spawned a “MkIII” sibling (with Jaguar V6 – half the V12 – and Triumph V8 engines) to be built alongside the Triump at their factory in Coventry, with Brown’s Lane continuing to produce the Big Cats and Speke concentrating on all sorts of Ajax-variants.

          • Guess it makes sense with Jaguar looking at less exotic more affordable and cost effective alternatives to the 1.8-2.5-litre Coventry Climax CFF/CFA V8 for the XJ Junior and other models. What is notable would be how along with one Triumph 2000 equipped with the Coventry Climax V8, another would also be fitted with what later became the Stag V8.

            On top of that it is fascinating to note the similarities between the 2-door only 2+2 Jaguar Small Saloon aka XJ Junior project and the Triumph Stag fastback, being of roughly similar sizes and powered by small capacity V8 engines (the Stag’s originally being 2.5-litres as was the Coventry Climax CFA). With Jaguar’s early attempts at an XJ saloon based GT loosely resembling an enlarged Stag fastback.

            It does make sense for a different iteration of the Jaguar XJ Junior to use the Triumph 2000 as a possible basis since the original Stag prototype (instead of the MGC derived bitza) and even the lesser known Reliant Bond Equipe mk3 prototype both made use of a shortened 2000 platform, although can see it using a version of the modular platform planned to underpin Puma / Bobcat / Bullet / Lynx.

            Forgot to add Saab later pushing its version of the Slant Four up to 2.3-litres equating to a hypothetical 4.6-litre V8, with others via kits managing to push the Four further to 2.5-litres. Perhaps small capacity Sixes and V8s of 2.0-3.0-litres+ could be the domain of Jaguar, with Triumph’s purview between 2.0-3.0-litres (~3.2-litre tops?) being archived with the Slant Four and V6?

            Just cannot see Triumph immediately progressing from Sixes to V8s as they intended in a scenario involving Jaguar and if otherwise, how Jaguar held back the Rover SD1 V8 pre-Vitesse (and in turn restricting the 2600 Six to 136 hp) offers a rough guide of how they would constrain Triumph’s V8 ambitions (probably a blessing in disguise in light of the later fuel crises).

            Heard it being mentioned in the Code Name: Triumph Stag Michelotti’s Masterpiece DVD that the Triumph Slant Four / V8 engine family was itself part of a bigger programme, which like Jaguar was to also include inchoate Sixes and V12s before they were abandoned early on in development. Has those claims for Triumph been substantiated, like Jaguar’s short-lived investigation into a Slant Four?

          • The Saab connection also opens up further possiblities for economies of scale had the original Ajax in FWD-form been twinned to the Saab 99 (or their successors, earlier than in real life). A Jaguar-Triumph-Saab combination making use of two common basic platforms (one FWD, engine in line, possibly later with 4WD, and one RWD/4WD to ultimately succeed Triumph 2000/Jaguar “MkIII” as well as XJ/S) might have been succesful against BMW and Mercedes throughout Europe and US.
            At first, Jaguar/Lyons might have restricted Triumph and Saab in possible upward ambitions, though that would seem less of a problem than with Rover, as Triumph would comfortably under any Jaguar range, as you suggest. Ultimately one would expect Leyland to be the dominant partner and open up possibilities for careful, profitable overlapping/economies of scale. In a Triumph 2000 range (or successor), inclusing the Stag, a smaller V8 could supplement Slant 4s and V6s at the top, while that same V6 would supplement a Jaguar MkIII (and related the XJ Junior) an the bottom of that range’s V8s.

          • Almost forgot: Saab also opens up further cooperation between Scania and Leyland on Trucks, of course

          • An Ajax/Gudmund JV that included scope for a supermini in the manner of Triumph’s own Ajax-based supermini project has promise, maybe with elements of Webster’s ADO74 project and what can only be described as an Ajax-derived Allegro equivalent (in the positive Michelotti styled sense).

            That would also remedy criticisms against Saab of the view the 99 grew too large to be considered a direct replacement for the 96 (see Indie Auto article “Saab 99/900: The box that crushed a carmaker”).

            There is also the potential addition of Rootes to consider (despite its own issues that compared to BMC’s were overblown), which would have provided:

            -) More capacity for the upmarket-focused Jaguar-Triumph combine and more commercial dominance by Leyland (via Commer/Karrier).
            -) The Avenger Four/V6, likely to be discarded or merged with Jaguar and Triumph’s synergised engine families.
            -) The upcoming Avenger, think potential Ajax successor below Bobcat with Rootes C6 proposal showing ability to switch to FWD, whilst in other respects pretty much paralleling Bobcat in Avenger Estate-based RWD form.
            -) Rootes C car, specifically the planned 5-speed gearbox and De Dion rear suspension for use in Bobcat/Puma family.
            -) Imp for better and worse, thinking of that Saab-like Autocar FWD Imp sketch leading to the idea it could be merged with Ajax/Gudmund as the starting point towards a fastback supermini (new Herald and Saab twin?), similar to how the Allegro was the starting point for what became the Maestro.
            -) A hypothetical Rootes/Leyland Sherpa analogue.
            -) And the addition of Roy Axe to eventually succeed Michelotti, with future Triumphs drawing upon Axe’s sleeker designs that were not too far removed from what Saab were thinking.

            Like Triumph’s work on the Pony 4×4, elements from the following Type Four derived projects by Saab like the Volvo 480-inspired Saab Fjord and others (see Saabplanet: Secret Cars that could lift a Saab) would have also been beneficial for both. Both Lancia and Saab looked at Type Four based coupes, with Saab even looking at a 7-seater 9000 MPV project.

            Not sure how long Saab would remain entwined with Jaguar-Triumph if GM makes an approach, yet Leyland would potentially benefit from an alternate “World Van” project replacing the Sherpa and Bedford CF if not even being in the running to gain Bedford itself during the 1980s.

          • On the other hand: would any form of cooperation with Saab have had much chance of succes, Saab having the very strong mind of it’s own that it always had (ignoring for a moment any attitudes with the British, particularly at that moment in time)?
            Perhaps better to concentrate on a hypothetical Jaguar-Triumph combination which would have been challenging enough, and to limit cooperation with Saab to further development of the Slant 4 engine.

          • Of the view Jaguar-Triumph would have benefited from the rub of Saab’s reputation for over-engineering, that although not completely positive (as GM found out) does share some parallels with the real-life Honda effect BL/Rover experienced from their largely mutually beneficial tie-up.

            Saab demonstrated how to repurpose an uprated Triumph 1300 (?) gearbox for the 99 and also looked at Stag V8 powered 99s before opting for the turbo. On top of further developing the Slant Four and even redesigning the H engine twice for both the 9000 (B234) and 900 NG (B204), Saab also revisited the V8 idea until GM stopped it.

            The nature of the Jaguar-Triumph co-operation with Saab would be an known variable, since as much as the latter has a strong will of its own at times and constantly sought to stray from a given brief for the sake of being different. At the same time by way of Saab’s then close relationship with Fiat in the late-1970s (producing the Type Four) they were willing to sell the short-lived Delta-based Saab-Lancia 600 and had minor input into the Delta’s development, with it and the Lancia-badged Autobianchi A112 also sharing Nordic showrooms alongside the 99/90 and 900.

            Unlike with Fiat, Saab by continuing to maintain a co-operation with Jaguar-Triumph would potentially be able to better cushion the costs required to develop new models below the 99/900 due to the pre-existing commonalties between it and Triumph though cannot imagine it being a long-term alliance.

    • Yes that would have been just 3 years of production at that rate!

      I think it’s been mentioned elsewhere that supposedly the block was strong enough to have a diesel version, but I’m not sure what commercial applications it would have had.

  3. the problem with fitting the dual cam heads on the V12 was that there wasnt enough easy room left for a decent induction system (inlet manifold). V12 I think is a 60 degree V (V8 is 90 degrees.

    • True, however It is an issue that both Ferrari and Lamborghini solved with their 60 degree V12s for example Ferrari Daytona or Lamborghini Espada hardly have high bonnet lines despite having quad cams. Also the installation in the XJ13 also seems no more bulky than the installation in the XJ12 and XJ-S.

      • Graham : are you sure you are correct about Ferrari and Lamborghini being quad cam. The V12s I have seen were all single cam

        • The Columbo engine was first given quad cam in 1967 for the 275 GTB/4, and then enlarged for the Daytona.

        • The Lambo V12 was always a quad cam from design and first run in 1963, it was done as such because at the time the Ferrari engine was a single can design. Ferrari as Daveh said below moved in 1967 to a Quad Cam head.

  4. @Zebo
    Whilst a Jaguar Triumph business following a sale to Leyland on paper would make sense with better synergies than the merger with Rover could ever have delivered. However it fails because of one problem, people, there was little if any respect between Jaguar and Standard Triumph at any level in the organizations and if Leyland had purchased Jaguar Lyons would have demanded autonomy for Jaguar as he did in the British Leyland merger.

    • I guess it would be very difficult to find any one or any company Lyons, being the character he was, would accept to play second fiddle to. I remember reading in the end he choose BMC because it had acquired Pressed Steel but, as Nate states, it seems he regretted huis choice very soon afterwards (even ignoring the following merger with Leyland Motors).

  5. Joining Leyland was something Lyons himself had considered if his biography is any indication had his old friend Henry Spurrier lived a bit longer, and while Lyons did not get on with Stokes that did not stop him contemplating joining as late as 1965 nor from later allying with each other to protect their own interests at BL.

    Lyons by that point bitterly regretted his decision to join BMC instead of Leyland and likely would have not done so had he known the true state of affairs.

    Do wonder if Lyons would have gotten on better with Alick Dick or Stanley Markland than with Donald Stokes.

    • You are right Lyons was open with the idea of merging with Leyland, but that would have been with the idea of Jaguar being a fully autonomous division of the Leyland Group. I doubt he would have had issues letting Leyland take Daimler Bus and the Climax Fork Lift Trucks away, as these were things that he had had to acquire to get the extra manufacturing capacity in Coventry as the Government would not allow the construction of new factories in the area. However he would have insisted in the cars retaining its independence for design, engineering and manufacture and the only restriction would have been not to venture into the sub 3 litre market to avoid competing with Standard Triumph. What he would not have accepted is that any Jaguar product was in any way associated with “Canley”, the reason think is that this for him represented Jaguar returning to its Pre War (SS cars) status as a coach builder using Standard Chassis.

  6. Could see it being the case that Lyons would initially have his own fiefdom within Leyland separate from Triumph, maybe it is the case that would also extend to their engines with Triumph having its Slant Four / V8 (plus small block four or Slant-based triple) and Jaguar its V12 derived family.

    In practice there was overlap between Rover-Triumph and Jaguar within real-life BL for their engines between 2.6-litres and 3.5-litres, so could see some creative reinterpretations and mental gymnastics occurring over time with the original stipulations (as Lyons influence wanes – although he did put a stop to the XJ receiving a VM Motori 6-cylinder diesel* before it was signed off for production in the late-1970s and almost sacking Norman Dewis over it), both with displacement-based tax special models and superficially which cylinder layout plus number is assigned to which marque.

    *- Essentially a 6-cylinder version of the 90 hp 2.4 turbodiesel used in the Rover SD1, which was used in a factory-approved conversion for the AMC Eagle rated at 150 hp.

  7. The smaller 2.8 engine found in the original XJ6 was withdrawn due to mechanical problems and being slightly underpowered. Thereafter, except for the slow selling 3.4, all other Jaguar engines were considerably larger than engines found in Rovers. It stopped any kind of overlap with the SD1 and made Jaguar feel more exclusive.

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