350bhp Jaguar XJC red herring 4.0 XJR6 power and we’re the first to drive it

350bhp Jaguar XJC red herring 4.0 XJR6 power and we’re the first to drive it

In a break from the usual Touring format, this one focuses more upon the car than the place. Peter Simpson visits Tom Lenthall’s workshop to drive a newly enlivened XJ Coupé.


350bhp Jaguar XJC red herring 4.0 XJR6 power and we’re the first to drive it


Peter Simpson’s been out and about in a supercharged XJ Coupé.

350bhp Jaguar XJC red herring 4.0 XJR6 power and we’re the first to drive it

Tom Lenthall has a passion for fast Jaguars. He restores, modifies and races them with boundless enthusiasm, something made possible by him being the proprietor of Berkshire’s busiest Independent Jaguar Specialist. Despite running a thriving business Tom has not taken a managerial back seat, remaining very much ‘hands on’, especially in the field of restoring and modernising classic Jaguars. In recent years Tom has worked on such celebrity cars as Harry Metcalfe’s XJ Coup. V12, rebuilding its engine and fitting a new fuel injection system as part of the restoration process.

“I must make it clear that fuel consumption is not the leading attribute of the this XJC-R.”

The XJ Coupe was a short-lived yet inspirational Jaguar model, adding an aura of sporting elegance to the luxurious XJ Series 2 saloon. As an XJC owner himself, Tom had long nurtured a simmering desire to do something avant-garde with this sophisticated gentleman’s coupe, and lurking at the back of his workshop was just the thing – a supercharged 4.0-litre XJR-6 engine from a mid-90s X306.

Tom knew it would fit without undue difficulty, as the XJ’s front axle was shared by the XJS, which carried this engine (without the supercharger) in its later years. The plot was hatched, although Tom chose not to employ his own coup. for the transformation because that is already rather special, being a V12 Lister. Instead, he bought a tired but relatively solid 4.2-litre example, sourced at a reasonable cost.

The idea was to carry out the project within a sensible budget that might be tempting to existing owners who fancied the idea of spicing up their own car. Of course, once underway Tom couldn’t leave it alone and the budget did become somewhat stretched. A lot of owners know that feeling too! At first glance the finished project does not look massively different from the car that Tom collected in Wales and drove back to Berkshire. This wasa major part of his philosophy, the idea being to retain the period refinement of the coup and, appropriately, the striking red paintwork topped by a black vinyl roof already presented the epitome of classic cool. The car had undergone some light restoration during the 1990s and benefitted from an exterior respray just a few years ago so, outwardly, little has changed apart from new wheels and period number plates. Inside, the cabin remains original wood, leather and decadent ambiance, although enlivened by a chunky Momo steering wheel and an all-important gear lever, the transmission previously having been automatic. The pleasing silhouette of the coup. is undisturbed, yet this is a fa.ade disguising a gentleman thug, a prize fighter in stealth attire. Beneath the surface dwells a potent machine that bestows road warrior status upon its driver. The original 4.2 was a fine engine in its day, somewhat stifled in twin carburettor form and constrained by an antiquated automatic ‘box, although it held its own from 1970s traffic lights. However, what we have here is from a wholly different realm.

350bhp Jaguar XJC red herring 4.0 XJR6 power and we’re the first to drive it


So, what did this transformation consist of? There was much discussion between Tom and his talented team as to the balance required to maintain the appearance and dignity of the original coup., while transplanting into it a vigorously beating heart. It was vital not to unsettle the fundamental characteristics of composure that were to be expected from this era of Jaguar’s magic carpet ride. The estimate was to approximately double power output from 180bhp to around 350bhp and torque from 228lb ft to perhaps 370lb ft. Bearing in mind that a 45-year-old car was unlikely to achieve anything like these original figures, this would be an astonishing boost. Naturally, the brakes and handling would require much upgrading to ensure the ability to cope, yet must still deliver a compliant ride. Starting with the engine, the rather shabby looking XJR unit had been lifted from a car destined for breaking so it was completely stripped, rebuilt and polished. A bigger supercharger pulley was fitted along with larger, electronic throttle bodies, all complemented by an Emerald fuel injection system. On the standard XJR air induction is through an airbox that is linked directly into the plenum on top of the engine, after which the air becomes restricted by being channelled around corners. Improved air flow was always on the agenda and Tom has cleverly fabricated an air box on top of the radiator with hoses leading more directly into the engine. The exhaust gases are expelled swiftly through over axle pipes and restricted only by two silencers at the rear. This has the benefit for providing a sonorous experience appropriate to the power output without being excessive. The manifolds are ceramic coated helping to control heat levels when exuberance dictates!

“The idea was to carry out the project within a sensible budget that might be tempting to existing owners”

The gearbox is a Getrag 5-speed manual unit linked to the engine by a very capable TTV ceramic racing clutch. Moving on to the steering and suspension, a later rack from an XJS was sourced and finished off with the three spoke Momo steering wheel, the centre infilled a leather XJR motif to lift the sporting image in an otherwise relatively standard interior. Uprated springs and Gaz adjustable dampers take care of the suspension and a limited slip differential assists handling.

350bhp Jaguar XJC red herring 4.0 XJR6 power and we’re the first to drive it

For the diff itself a sporty ratio of 3.54 was chosen to enhance performance whilst still maintaining sufficient cruising comfort. The front and rear axles are not the originals from the car because it was considered too time consuming to remove them, rebuild and powder coat while the car needed to be moved around, therefore others were restored in readiness for more rapid replacement. With the extra power on tap the car required uprated brakes, for which the Brembo system used on the XKR was chosen as the ideal solution. Clearly the wheels had to fit over the larger discs and Tom’s solution was a set of 17-inch alloys, those specified in the original X300 XJR launch car, which also provide a pleasing continuity with the engine.

The body was reasonably solid with only minor corrosion. The engine bay was repainted and the car thoroughly undersealed. Replacement fuel tanks were installed from a Series 3 to provide the fuel return system required, something that was not incorporated into the original car, which ran on carburettors. All wiring and cabling was renewed and every nut and bolt was either replaced or replated.


After all this work did the performance live up to expectations? The car was apprehensively strapped to the dyno and the results eagerly anticipated. The original estimate of an increase from 180 to perhaps 350bhp was favourably improved to 370bhp. However, the torque, initially guessed at a rise from 228lb ft to maybe 370lb ft smashed all hopes when the dyno revealed a staggering output of 464lb ft. This is a seriously raunchy motor for something nearly 50 years old and I felt it was time to politely ask Tom if I might take this trenchant weapon out for a road test, for the benefit of you dear reader, as I was sure you would be curious. I certainly was.

The Berkshire and adjacent Hampshire countryside surrounding Tom’s workshop is pleasantly wooded and looked particularly colourful in its late autumn hues. A mixture of road types and suitably grand static locations were compiled and more than a modicum of high octane petrol added to the tank. I must make it clear that fuel consumption is not the leading attribute of the this XJC-R, although these were still the early days of shakedown assessment and fine tuning will doubtless improve the figures. And besides, road testing is designed to be just that – testing. I was not planning to practice sedate manoeuvres and as Tom says the whole point of this car is to have fun, so I took him at his word. As for the basics, the desire to retain the essential characteristics of a floaty Jaguar is not especially compromised. The balance is pretty much spot on.

“The pleasing silhouette of the coupé is undisturbed, yet this is a façade disguising a gentleman thug, a prize fighter in stealth attire.”

The ride is comfortable and far superior to any of the hot hatches that may attempt to pour scorn on the old man at the traffic lights. This brings us to consider some adjectives that may become appropriate when those lights go green; explosive, ferocious, intense, rampant and utterly thrilling. The hot hatch is history, the new kid on the block is the cool coup… Nonetheless, this XJC-R is for the man of all seasons. Pop a pipe in your mouth and granddad can tootle to the shops for his Sunday papers with his car attracting respect as the deserved classic it is. Even the youngsters will acknowledge the undeniable appeal of the bright red paintwork contrasted by the time-warp black vinyl roof. It’s distinctive and unconventional in this anodyne modern age.

I did, however, harbour one concern before stepping boldly into the driving seat. Having previously driven cars with racing clutches I was aware that what is designed for the track may not be entirely suitable on the road. With some set-ups it is often a case that either the car is stationary, with latent intent, or instantly propelled into the hedge opposite. Thankfully, this clutch has middle ground and I must confess that I completely forgot its track based underpinnings when amidst dawdling traffic. When the congestion cleared and my right foot accidentally pushed a tiny bit too far, suddenly there was the rush of remembrance of what lies behind that pedal – a charging red bull, the howl of its supercharger provoking a surge of adrenal stimulus. By the end of the drive I had christened the car the ‘Janitor’, curiously you might think, until you realise it could wipe the floor with everything it sees.


Although not entirely finished, the XJC-R made its first public appearance at the NEC Classic Motor Show in November 2023. It was displayed on the Jaguar Breakfast Club stand with the bonnet open to reveal the unexpected vision of one of Jaguar’s most aesthetically appealing engines. The club’s volunteers were mobbed and excitedly explained the restoration to visitors, progressively elongating the ‘R’ with a west country burr. By the end of the weekend, it was an XJC-RRRRRR. The car was certainly a crowd pleaser and this got Tom thinking about the future for this desirable ‘Restomod’.

With the sad loss of his dear friend Emma Andrews recently, Tom has decided to auction the coup. at next year’s Classic Motor Show, the profits being donated to charity. And because Emma was a keen offshore diver her links were with the RNLI who will benefit from this heartfelt gesture. In the meantime, there are few finishing touches to complete. The bumpers will benefit from rechroming and there are a few minor paintwork blemishes to sort, following which the car will be paraded around the country, enticing admirers. Whoever bags this beauty when the hammer goes down will have bought a new car in old clothes with a split personality. It’s two Jaguars for the price of one.

There were many surprises when Classic Motor Show visitors looked under the bonnet. The public were enthralled. Suspension is sharper but compliant.

The Elvetham Hotel provided a stunning backdrop.

A first run out into the country. Will the new supercharged engine fit? The XJC becomes an XJC-R New axles with added stopping power The dyno sheet results were impressive.

The original 4.2 engine is removed But it’s a lot. better now. It could have been worse in there.

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