THI MOTORSPORT
THI MOTORSPORT

This page provides links and copies of web and magazine based features that we have been involved with.

Below, are the three months worth of features that we were involved with, regarding the aerodynamics of the car. Thanks go to Race Car Engineering Magazine and Simon McBeath

A review on the car from a passenger perspective. Thanks to SELOC and Andy Swift.

A ride in the EP Tuning Time Attack Exige

Since my earliest days watching motor racing I’ve always had an over-arching fascination with two things: Oulton Park and ludicrously fast club-level racing cars. I had never really thought these two passions might combine into anything more meaningful than enthusiastic spectating and occasional reporting. Yesterday, though, I had the opportunity of a lifetime to experience Oulton from the passenger seat of one of club racing’s fastest machines.

Along with my love for club racing and Oulton Park, I’ve also developed something of a fascination for Lotus. Unfortunately my bank balance is frequently depleted by a troublesome little S1 Exige which provides equal parts bliss and despair. I rather get the impression that Jamie Willson shares this ‘special’ relationship with his Exige.

 

Jamie owns an S1 Exige too. The primary difference between us being that he got a little carried away with the modifications; so carried away, in fact, that his bewinged monster now generates 600kgs of well-balanced downforce. And it’s motivated by a 650bhp compound charged Honda K20a engine. That means a supercharger for instant torque and a massive great turbocharger to carry it on a boosted swell to 8,500rpm.

As I’d agreed to write an article on the car, Jamie thought it might be worth me experiencing its performance from the passenger seat; to offer a little anecdotal spice to proceedings. It’s fortunate that I’ve had 24 hours to recover a little objectivity otherwise my summation might’ve been a quivering mess of profanity.

My chauffeur for a few laps of Oulton Park’s International circuit is legendary independent Lotus engineer and driver Simon Scuffham. Bedecked in Jamie’s race clobber and with my spectacles awkwardly bent into his helmet my surroundings were familiar and intimidating in equal measure. With my movement severely limited by the presence (reassuringly) of a chunky roll-cage and carbon bucket seats, any degree of claustrophobia would need to be stifled instantly. The sight of Scuffers in his open-faced helmet with his aviators on added a level of surreality to the whole affair.

After a short wait in the garage in pretty serious heat we were chuntering along the pitlane and out onto the track for Time Attack’s Pro category morning warm-up. No time for messing around and it’s flat out in second, third, and what’s this…fourth through Dentons with the pedal mashed to the floor? But when are we going to brake for Cascades? Ye Gods, we’re through Cascades in a single violent arc before I even have time to curse my imminent demise.

 

Along Lakeside and we’re going through gears so fast via the paddleshift ‘box I barely have time to swear before we’re barrelling into Island bend. The speed Simon is able to carry through here is the most vivid demonstration of the car’s potential. Along Lakeside the acceleration is savage – changing up into (what I presume is) fifth only seems to bring an even harder kick. The braking events are so short that I barely have time to consider their severity before we’re back into corners again. The downforce and slick tyres are really working through Island and the time we’re making up on the other runners is comical.

There’s oil down on the run from Hilltop to Knickerbrook so Simon is necessarily cautious under braking. Brett Winstanley in his mighty TVR Sagaris sends up a huge plume of cement dust from the trail of oil. From the exit of Knickerbrook, though, everything is moving very quickly indeed. Clay Hill looks a relative innocuous crest from the spectator areas. Under full-bore acceleration in the Exige it feels akin to cresting Everest. While cornering hard. Have I mentioned how fast this thing is?

Turning into Druids is made all the more entertaining as I initially believe that Simon has entirely forgotten how his brakes operate. This fearsome double-apex right hander is approached at flat chat, with a moment of heavy braking, a downchange and then hard back on the power for the run to Lodge. If I had time to consciously do so, I’d have shaken my head at the lunacy of the whole affair.

Into Lodge, Winstanley’s TVR is finally dispensed with and we can really start getting a shuffle on. Oulton Park is rarely straight, and even less often flat. The Exige’s staggering composure in all circumstances allows Simon to work it hard everywhere. It’s stable under braking, the downforce tears your head from your shoulders and the traction is such that no amount of crests and cambers prevent Simon from using full throttle openings by the apex of any given corner.

 

After three bruising, pummelling, laps the car suddenly struggles to find a gear. We cruise into the pits where it seems miraculously to regain its mojo. With tyres pressures checked it’s back out on track. Here we go again – hammering down Dentons. Sadly this flyer only lasts until Lakeside when the turbo hose pops off. Simon manages to diagnose the problem from the cockpit and the car is soon back in the garage cooling down. No damage done and it’s ready for the next session.

Given traffic and oil on track, we never manage a clean lap. In addition, Simon isn’t running full boost and claims not to have been really leaning on the car. Bloody felt like it to me. Our session best is a 1:48 which isn’t bad given the circumstances. Next session out and Simon nails the monster Exige to the top of the timesheets with a 1:40. It’s staggering stuff, and to offer a little perspective, would’ve qualified him comfortably on pole for the GT Cup race at Oulton a week earlier, and well into the leading Radical runners the week before that.

So I’ve managed to avoid the profanity but I’m really struggling with the superlatives. Compared even to a conventional road-going Honda-engined Exige, this thing is…well, there’s no comparison. It’s ludicrous, ridiculous, staggering, and mind-bending. Even after just three quick laps I’m starting to feel the effect on my neck and I’ve dislodged the footrest from trying to brace against the multi-directional forces. It’s absolutely fantastic though and I’m itching for more laps. Before the run I was worried I would be revisiting my breakfast. Not a bit of it. My stomach is settled but I’m riddled with adrenaline and my hands are quivering as I emerge.

The car is, as you’ll have gathered, stupendous. Equally impressive, though, is Simon. He is utterly composed and fearsomely committed. While my poor brain struggled to compute the speeds we were going he was nailing every apex. There was no showboating and no ragged moments, just searing progress.

I find out afterwards that Jamie himself hasn’t been out in his car this season adding to the immense privilege of the experience. Even better, he is terribly apologetic to me for having the session interrupted by mechanical malaise and implores me to come back for another go; this time running full boost. Well Jamie, in the interests of journalistic research, it’d be rude not to, wouldn’t it?

SELOC would like to thank Andrew for allowing us to share his article. You can find more of his work on his website, Motor Car Diaries and in his look under the skin of the EP Tuning Exige on RaceTech Magazine.

This is a 2 part review of the car in Race Tech Magazine. Thanks to Race Tech Magazine and Andy Swift

Maximum Attack (pt1)     

Written by 

            
              
Maximum Attack (pt1)     
 
  

In the first of a two-part series Andy Swift meets one of the rising stars of the UK Time Attack scene to find out about his much-modified Series 1 Lotus Exige

  

Race Tech has recently spent some time grappling with how motor sport can help engage with a younger audience – the so-called ‘Generation Y’. With many branches of the sport remaining the domain of an ageing audience, youngsters of 2013 are the products of an era dominated by Gran Turismo, PlayStation and an automotive culture distinctly influenced by Japan.

Set against this cultural backdrop is Time Attack. Recently described by one sage commentator as, “a track day you can actually win”, this branch of the sport has been imported from Japan and has already proven itself to be a tremendous success.

A neat metaphor for this Anglo-Japanese championship is the crazy Lotus Exige of Jamie Willson. Powered by a Honda K20a engine, of the kind originally installed in the Honda Civic Type-R, Willson’s Exige is now compound charged to create one of the wildest machines in the UK race scene – a perfect storm of English lightweight chassis know-how and high-revving Japanese engine technology.

The Series 1 Exige was a road car developed from a race car, and in Willson’s case now returned to a race car. His example is one of Lotus’s development prototypes, and blessed with an illustrious past, as he reveals. “It was the exact car driven by Tiff Needell on Top Gear and by Jason Plato on Fifth Gear and many moons ago and also appeared in a couple of magazines.”

Despite this provenance, it wasn’t long before Willson was bitten by the modifying bug: “Within a few weeks, the original VHPD engine had been removed and shipped to someone in the Far East to be put in a race car. The Honda engine conversion then followed very shortly after.”

Time Attack differentiates itself significantly from other circuit competition because it doesn’t feature wheel-to-wheel racing. Competitors take to the track together, but rather than racing for position, the drivers aim to set the fastest possible lap during each session.  It might be loosely described as a track day crossed with a traditional qualifying session.

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Despite being recognised as an MSA-approved championship, Time Attack’s unusual format has reduced the number of hurdles facing track day enthusiasts wishing graduate into competition. Several factors enticed Willson into having a crack at it: “Time Attack is very relaxed with regards to the modifications you can make to your chosen car and, apart from strict safety regulations, pretty much anything goes. In the lower classes there is no requirement for a racing licence, which again made it very accessible to me.

“I also wanted to take part in something which wasn't a big commitment in terms of time spent away, i.e the number of events that we had to compete in.  Lastly, I didn't want to do any proper racing in order to try and cut down on the potential risk of damage to the car. Time Attack is strictly non contact and is run by almost the same rules that you would find on any normal track day.”

While the purists might baulk at the lack of genuine racing, it’s apparent that the technical freedom afforded to teams has made it one of the most liberal categories in the country. Many of the nation’s top tuners have chosen to use the championship as a showcase for their abilities. For firms like Milltek, it has offered a shop window to a demographic which features tuning enthusiasts and track day regulars – their key customers.

The top Pro classes have historically been the domain of the Japanese four wheel drive monsters from the likes of Nissan, Subaru and Mitsubishi. Willson and his team, though, are gunning for outright wins with their rakish Exige, which has now been developed beyond recognition – mechanically and aesthetically. The project has entailed innumerable different companies and a huge degree of completely bespoke work.

The decision was driven by the ambition to step up to the top Pro Class, Willson explains: “At the end of last year, after winning the Club Pro championship outright, we decided to make the step up into the Pro Class and compete against some of the UK's finest tuners and Pro drivers. During last year, and also 2010 when I won the Club Pro RWD championship, we had always been using a bog standard Honda K20 engine with different cams and a supercharger bolted on. This produced enough power to make it competitive in those classes, however just wouldn't cut it in the Pro Class. We needed something quite a lot more potent to stand a chance against the other machinery, some of which produces upwards of 1,000bhp. We also needed an engine package that made the car useable and friendly to drive.

“The engine we have is a high revving, small 2ltr and bolting on a huge turbo to get the power we would need would bring along with it a fair amount of lag. Bolting on a bigger supercharger would probably not have given us quite enough power. Therefore we just thought, ‘what the heck, let's just get the best of both worlds and use both!’ We know this isn't something that a lot of people do, especially on a circuit racer, as it's fairly complicated. However, all the hard work has paid off and we now have an engine package that produces huge amounts of power and torque from very low rpm, has zero lag, excellent driveability and still revs all the way to 9,000rpm.”

Willson shares driving duties with Simon Scuffham of Link-Up, who has lead the development of the powertrain for this unique racing car. Scuffham has been one of the pioneers of Honda conversions for Lotuses for many years. Despite considerable experience of supercharging these units, this was Link-Up’s first effort at compound charging. Matthew Bentley Racing runs the team, with input from a number of contractors and suppliers – many of them familiar within Lotus circles.

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Extracting this kind of power and making it workable in the Exige has not been easy. The engine was built by Paul Exon of Exon Racing Engines, with many parts being shipped from the US, “We now have a great engine fitted with Darton MID liners to cope with lots of boost, 89mm CP Carillo 10:1 flat-top forged pistons, Manley I-Beam connecting rods, ACL bearings and a Cometic multi-layer headgasket. These are all off-the-shelf parts in case we need anything quickly in the future.”

Remarkably, the head has been left completely standard, with the exception of the deployment Eibach valve springs.  The team decided not to use a brand-new, crated engine. By employing an engine which had already been through multiple heat cycles, it enabled a more stable platform for such extreme modification.

The turbo arrangement was assisted by Turbo Dynamics, who supplied the turbo and wastegate set-up for the engine and advised on the best parts to use. A Garrett GTX3582r turbo is employed cold side with up-rated bronze bearing carrier, and a stainless Tial GT35 hot side with 1.03 A/R ratio. A Tial V60 wategate controls the boost and a Tial Q50 deals with excess pressure.

This set-up has brought its own issues, Willson laments: “Our first sizeable problem was that our first stab at getting the correct size of wastegate went wrong. We fitted a Tial 44mm MVR wategate, but only found out on the dyno a couple of days before our first event that it simply couldn't control the amount of boost that we were creating. This meant that we couldn't map the engine properly and then resulted in a DNF at Cadwell Park, when we blew the headgasket due to a boost spike.”

With the team learning how to control these huge levels of boost, providing the greedy powerplant with enough fuel became the next problem, as Willson recalls with a smile:  “On the dyno doing full power runs, the engine was consuming between five and six litres a minute! As a result, we had to fit a new high flow Bosch 044 pump to feed off a new bigger swirl pot and also squeeze in an additional in-tank pump to feed the swirl pot. Even now, we are running at well over 90% duty cycle.”

Unusually for a road car, the Exige features a roof scoop. The road-going models used this simply to allow cool air into the engine bay but Willson’s team has modified the standard roof to use this for induction. A K&N air filter is housed in a gold-lined airbox. This location is up in clean airflow, keeping filters clear of debris and enabling optimal induction. The team had previously used one of the air scoops on the flanks aft of the doors, as per the original arrangement, but found the filters were clogging up too easily.

Pro Alloy Motorsport has long supplied cooling solutions for Lotus owners and their aluminium radiators are popular modifications for road-going Elise and Exige models. The manic Time Attack Exige has required a completely bespoke solution, working within the tight confines of the Exige’s aluminium chassis and fibreglass body.

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The main radiator is front-mounted in the usual Exige position – in this instance a triple-pass motorsports unit topped with a puller fan. Also at the front, under the crash structure, is the first of the intercooler pre-rads. In the back of the car is another large intercooler pre-rad sitting behind the nearside side scoop, with a puller fan mounted to it as well.

There is also a pair of heat exchangers within the engine bay, each serving a different purpose. The larger unit sits after the turbo with a dense single core, sandwiched between the supercharger and inlet manifold. The car cannot accommodate a big post supercharger intercooler so the supercharger is gradually bypassed once the turbo starts coming into action, in order to avoid the associated heat that would be generated. Finally, a specially-fabricated water jacket keeps the wastegate cool.

Keeping engine and gearbox oil cool and at the necessary pressure has also provided its own challenges. As a result, two Mocal Laminova oil coolers have been installed. A large one manages the engine oil temperatures, with a smaller one performing similar duties for the sequential gearbox. In a bid to keep oil pressures properly-regulated under the provocation of such extreme cornering and braking forces, the team has elected to install an Accusump oil accumulator for this season.

Transferring all this fearsome boosted power to the road is a sequential, paddleshift gearbox. This unit has been developed specifically as a solution for Toyota and Honda engines by Eliseparts. The control system for the six-speed ‘box is by Geartronics with the final drive ratio set to 3.7. A Wavelength limited slip differential manages getting all that boosted power smoothly onto the track via slick Dunlop racing tyres.

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Maximum Attack (pt2)     

Written by  Andy Swift

            
 
              
Maximum Attack (pt2)     
 
  

In the second part of this feature, Andy Swift talks to Jamie Willson about the mechanical and aerodynamic specification of his 600 bhp Time Attack Exige

  

It's easy to get sidetracked by the power of this car. In the previous article we looked at Jamie Wilson's quest to extract 600 bhp from the 2-litre compound-supercharged engine in his diminutive Lotus Exige. But beyond the car’s wild, Lancia Delta S4-aping drivetrain, lies an equally rigorous development programme for the chassis and aerodynamics.

The basic Exige chassis is a very stiff bonded, extruded aluminium tub and doesn’t benefit from a huge amount of additional bracing. However, the rear sub-frame has strengthened to prevent twist as a result of the new forces introduced by the vehicle’s extreme dynamics.  

The suspension features endless upgrades, as Willson reveals, “last year we fitted EP Tuning anti-roll bars & mounts, T45 rose-jointed race wishbones, race steering arms, adjustable bumpsteer kit, front & rear Race GT hubs and bearing packs with 5S99G high tensile steel hub stud kit, along with 4-pot brake calipers front & rear.”

If these measures weren’t comprehensive enough, the team is now experimenting with cutting-edge damper technology, courtesy of long-time partner, Quantum. Having run with two-way adjustable dampers for the past couple of seasons, the team is now helping to develop a new four-way damper, known as the X Series.

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Willson explains the advantages these dampers can confer: “These new units are a recirculating design and the oil passes around the outside of the shock absorber, as opposed to through the main piston as is the case with mono-tube shocks. In both bump and rebound, oil is compressed between the main piston and the valve head. The floating piston, separating the oil from the gas pressure charge, is behind the valve head and is never exposed to the high pressure on the damping side.”

This means the shock can generate significantly greater damping forces than are possible with monotube shock absorbers, with significantly lower gas pressure too.

What sets the X Series apart from similar designs is the unique method of adjustment. In place of the traditional needle-and-jet, the X Series employs a drilled bleed adjuster, explains Willson: “every X Series low-speed bleed adjuster has eight positions corresponding to eight drilled bleeds. At position one, one bleed is open. At position eight, all eight are open. Each bleed can only ever be open or closed and there is no in-between.”

Four different bleed adjusters are available, ranging from fine to coarse adjustment. The design offers a significant improvement in usability, with almost digital operation and clear, precise adjustment when compared to the previous two-way dampers. The dampers are still in the early stages of their development, and Willson admits that the team is still fine-tuning its set-up; as pictures of the car lifting an inside front wheel under hard cornering at Croft attest. The extreme lateral forces the car is now capable of will continue to challenge the engineers as they zone in on an optimal mechanical set-up.

tunnel rear

In road-going form, the Exige became noteworthy for producing negative lift straight out of the factory. As standard, the car features a flat floor, Kamm tail, aluminium diffuser and a rear wing mounted atop the fibreglass clamshell. While these measures do produce downforce at track speeds, they are completely insufficient for the kind of performance which takes overall wins in Time Attack. The team has been lucky to enlist the help of highly regarded aerodynamicist Simon McBeath, who designed the rear wing and helped arrange time in the full-scale wind tunnel at MIRA to prove the concept.

The car is, in fact, still on its original bodywork, although some modifications have been required.  The front clam now features louvres cut into the wheel arches reduce high pressure build up from within the arches. Otherwise, apart from some vent covers to improve airflow at the front, the clam is standard. The rear clamshell has been modified slightly to accommodate wider rear wheels.

Willson describes the multitude of measures at the sharp end of the car: “We now use a 20mm deep ally front splitter instead of the old plywood version. This runs under the front of the car, joining up with the flat floor and is fixed directly to the front crash structure. The reduction in the splitter material thickness gives us more front ground clearance and allows us to run the car lower.

“The leading edge is turned up to create a nice radius so that the air that encounters it doesn't get detached from the flat floor that follows, basically simulating a thicker splitter with a generously radiused leading edge. At the sides of the splitter we have some big fences to trap the air and generate downforce. To the side of these, inverted tunnels create vortices down the side of the car to seal the underfloor. Dive planes are also incorporated into the front clam for additional downforce.”

One of the Exige’s most prominent features compared to its road going brethren is the enormous front wing. This is mainly used to create a forwards shift in downforce balance, allowing the team to run the rear wing at steeper angles of attack.

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The same focus is applied to the rear, where the usual louvred engine cover has been replaced by a smooth non-vented version to improve airflow to the big rear wing. The pre-preg carbon, twin element rear wing was designed by Simon McBeath.  This is mounted further backwards than normal to get the cleanest air, using bespoke, adjustable knife-edged struts which are then bolted directly to the rear chassis members, rather than into the fibreglass clam on the road car.

Willson describes how hard the team is trying to work the car’s floor as well as upper surfaces: “At the back we run an ally diffuser, much wider than the standard item and also deeper, but with the same ramp angle. This joins onto a new floor panel which eliminates some of the large wheel area cut-outs of the standard part, allowing the diffuser to drive the rest of the flat floor as efficiently as possible and to interact with the rear wing.

“For the sides of the car, between the front and rear wheels, we run wide running boards in order to help prevent airflow from outside the car entering the low pressure zone underneath - a gain maximising what's available to us. These running boards are further enhanced by using vertical strips of runner skirting to seal them close to the floor.”

track rear

The team has suffered from a couple of minor reliability issues in the opening rounds of this year’s championship, but is now confident it is on top of these and is gunning for overall wins over the rest of the season. The car itself is now producing just under 600bhp at the hubs and - weighing only 825kg - this means performance is appropriately vivid.

The racing purists will still doubtless still take issue with the lack of perceived racing involved in Time Attack. What cannot be denied, though, is that the championship has created a regulatory framework sufficiently loose that it permits the creation of some of the country’s fastest road car-derived circuit racers. If a crazy, bewinged, Exige can't raise Generation Y’s collective pulse, then perhaps nothing will.

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