December 2013 \ Jaguar World Monthly | 55

MODIFIED XKR BADCAT

54 | Jaguar World Monthly / December 2013

MODIFIED XKR BADCAT

With a six-speed manual 'box, over 500bhp from its V8 and a potential top speed of 190mph, the Badcat XKR isn't your average X100. We visit the Sussex-based company that built it to experience this phenomenal machine for ourselves

W O R D S & P H O T O G R A P H Y N I C K G I B B S

WHEN WE look at a Jaguar the majority of the time we see power, elegance, sophistication, or a combination of all three. Graham

Wood looks at a Jaguar and sees… potential.“I’ve always power-enhanced my cars, since being a

lad,” he tells us. Since retiring from advertising, Wood has turned an obsession into a second career and created a business card like no other: a 500+bhp, 190mph XKR with upgrades that a skunk-works performance division Jaguar itself would be impressed with.

He winces ever so slightly when you ask exactly how much money he’s poured into this XKR, bought as a mostly stock car second-hand from a forecourt six years ago for £12,995. With a look that says ‘don’t tell the wife’, he admits to a further £15-20,000-ish.

But this obsession that has seen Wood upgrade, replace or even redesign most elements of the standard 370bhp four-litre supercharged V8, which has satisfied him to the point that he’s selling on what he’s learned as a new company: XK8/XKR Power Developments. He figures he can’t be alone. “I’m looking for people like me who want to make their Jaguar go faster,” he says.

Wood compares himself to a musical director or conductor of an orchestra. “I know how a piece has to be played and the way I want it to be played, then I go and hire the very best musicians to work with me,” he says. He has built a network of guys he reckons are the best in the game to help create the powerplant, reprofile the cams, install and tune the powerful new ECU, fit the manual gearbox, build the

stainless-steel manifolds, even fit bespoke harnesses. Wood’s obsession with upgrading the engine to

wring out every last ounce of hp is in many respects very American. The billion-dollar tuning industry in the States with its crate V8s and quarter-mile heroics has been transplanted to leafy Sussex and a cup of tea thrust into its hand.

Of course, the two V8 engines Wood has come to know well, the AJ26/27 and the later 4.2 AJ34, are American in that the cylinder configuration is much more associated with that country than the UK. They were created by Jaguar's engineering centre at Whitley to replace the old straight six AJ16, and like any standard engine, there's plenty of leeway for improvement.

“Jaguar built everything to a cost. They built a car that worked very well, and went very quickly but it was kind of standard,” Wood says.

He went with the XK because he loved the shape, and looking at the car he dubs ‘Badcat’ you see how well the muscular beauty of the X100 design has aged. Wood’s addition of the yellow band surrounding the oval grille has a Jaguar link in that the D-type that won the Rheims 12-hour in 1954 sported a similar band. In the flesh the modification works well, especially minus the original mesh grille.

The idea is that customers will pick and choose from a menu of enhancements, all of which can be viewed on the Badcat. It’s all a bit real-life Gran Turismo in its shopping list of bhp upgrades, starting with what Wood calls the ‘known mods’. For example, 20bhp by putting on a small top pulley (£285 fitted). And perhaps another 15-20 bhp with a larger bottom

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MODIFIED XKR BADCAT

pulley (£395 fitted with new belt). That means it spins faster and builds more pressure to help force more air into the cylinders. That’s the easy bit.

The trick ECU brings greater reward at an estimated extra 50-60bhp. Much greater cost too, at £3,995 (all prices including VAT), although this does include the hardware, integration into the management system and many hours of analysis and experienced re-mapping on the rolling road. And this powerful package of electronics brings the ability to tune each individual cylinder to optimise the fuelling for either all-out bhp, greater torque or even economy if that’s your bag.

This is done by one of Wood’s lead musicians, a highly respected racecar tuner working out of Silverstone (Wood won’t name him) whose rolling road sessions show you exactly the spread of power a more precisely controlled engine will develop. The sophisticated AEM box reads a range of sensors that feed into a digital dial neatly embedded alongside factory dials on the dash that displays results for revs, water temperature, throttle position, air intake temperature and other racecar-specific info that you should probably get your passenger to sing out rather than try and absorb yourself. Sensibly, apart from the bespoke Luke four-point harnesses, it’s the only modification to the still-elegant interior.

The engine upgrades are worth 70-80bhp according to Wood and ups the size to 4.4 litres. This isn’t a complicated rebore; instead, Wood uses the block from the Range Rover that came with a bigger version of the same engine. That was more designed for torque he says, but this version gets Wood’s new ported and polished heads with its high lift cams from Catcams and specially built pistons made by Mahle (to avoid the old ones clashing with the valves post cam-change). A recent dyno run shows the car is making 525bhp at the flywheel and 495lb ft of torque @3500rpm but with the revs limited to 6300rpm. Wood reckons there’s more to come.

In addition to the modified fuel rails and pumps, the large rammed cold-air induction, fed from vents fitted in place of the old fog lights and the uprated MAF meter, the Badcat is fitted with an RX Superchiller (£1,075). Imported from America where it is used extensively for drag racing, this unit ‘refrigerates’ the charge cooler fluids, helping reduce heat soak air intake temperatures, which so badly affect power stability (through the vapour density and timing retardation). Power Developments technical associates at TL Jaguar are charged with adapting and fitting these units.

Even without the additional performance technologies, a basic new-build Badcat engine, when installed, will cost around £12,000.

The mod Wood is most proud of and one that could potentially be most satisfying to fit are the new 4-2-1 stainless-steel exhaust manifolds. He

Interior is standard, bar... the six-speed manual Tremec ’box, a third dial for displaying ‘racecar-specific’ information, and those bespoke Luke harnesses

The Badcat has an estimated 0-60 time of just four seconds

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MODIFIED XKR BADCAT

reckons the vastly improved gas flow from these and the straight through system extracts another 25bhp from the engine output. “The original Jaguar manifold is a lump of iron you’d probably say was Victorian if you found one,” he says with a laugh. Costing £1,980 for the pair, Wood’s love of them comes from the fact that he had them designed and also built jigs to ensure they’re fabricated precisely. “I spent nearly two years travelling around the country trying to find someone to help me design and make the system. And to a man they all said it can’t be done; the engine bay’s too small,” he says. But eventually he found someone with the skills to do it and at the right price. The tubular exhaust manifolds (which Wood also had Zircotec ceramic-coated to reduce further heat soak in the engine bay) now form part of a full exhaust system that includes 64mm downpipes with two easier-breathing 200-cell catalytic convertors (“about as little as you can get away with”) costing £1,548 and a 64mm CAT-under axle exhaust system with tail finishers for £1,193.

The exhaust is also responsible for the hellfire serenade that assaults you when you mash the pedal to the floor. The signature whine of the supercharger is amplified but the noise isn’t just the deafening thunder crackle of an American muscle car – it’s more pedigree than that, more racecar with the promise of a lot more revs.

This car is all about the accelerator pedal and the heart-in-mouth rush pressing it brings, so it’s only fitting that it has two pedals alongside, not just one. No XK8 or XKR had a manual fitted as standard of course, so Wood has gone for a six-speed Tremec ’box imported from the US and fitted by his principal technical musician, Tom Lenthall, owner of TL Jaguar. Gearshifts are slammed into place rather than snicked and there’s absolutely no doubt that you’ve meshed – it’s that mechanical in feel. I found the twin-plate clutch Wood is using right now way too heavy for comfortable use, but I did love how shifts thrived on heel-and-toe changes, possible from the close-set pedals.

Wood agrees on the clutch workout, and the plan is to swap this back for a single plater on advice he received from another of his expert network, this

time an ex Aston Martin race engineer who said they had no problem putting 600bhp through this box on a similar clutch.

Wood is not quite at that point yet. The Badcat ‘prototype’ you feel will always remain a work in progress and he is already plotting to do away with the already race-modified Eaton supercharger in favour of a twin-screw Kenne Bell to give him the opportunity to push even more fuel into those cylinders. Like anyone with V8, Wood speaks of impressive economy ‘on a run’. Unlike everyone else, ‘impressive’ to Wood is 15mpg…

All that power is corralled via a Quaife rear limited slip diff that has the side benefit of delivering a controllable tail slide on occasion. The XKR also has lowered and stiffened springs for a reduced lean angle, but although corner grip is very good on the 20in tyres wrapped around those Ascari wheels, the star act is without a shadow of doubt the engine and its ability to produce an absolutely phenomenal turn of speed. Wood reckons four seconds to 60mph and I can easily see it. A slight lumpiness in the lower rev ranges is something he plans to remap out, but I love how it urges me to press past it onto the silky uplands of the rev range.

Many would question the sanity of throwing far more than the cost of the car into the engine bay with precious little hope of seeing it again, but to Wood this is no more than the 'undervalued' XK deserves. As he says: “How good to have a bespoke and very quick, X100 that can compete in performance with the latest that Jaguar can offer, but at a third the price?”

Twenty-inch Ascari Penta wheels with rare Jaguar stud centres were powder coated to body colour

THANKS TO: Graham Wood at XK8/XKR Power Developments 01435 883988 www.xk8rpowerdevelopments.co.uk

Elegant Arden quad rear lights give the Badcat additional visual presence