Adrenaline High

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NEW CAR MURTAYA

ADRENALINE Not all championship organisers will welcome Adrenaline Motorsport’s latest creation, but enthusiasts are likely to love it. Chris Pickering explains why

M

EET THE Murtaya. It’s a machine built with one simple aim: to create a new niche in the fast road and motorsport markets. The car’s creator, Adrenaline Motorsport, is a small Cornish company which packs a distinctly international-sized punch. Chief chassis engineer Daniel Muir can count the Lotus Elise and Aston Martin DB9 amongst his previous endeavours, and managing director Neil Yates has been a senior manager with several multi-national companies in between rallying everything from Mk2 Escorts to Audi Quattros.

The niche that they’re aiming to create is the affordable four wheel drive sports car. It uses the venerable Subaru Impreza drivetrain, coupled to a bespoke composite monocoque to offer explosive performance along with excellent reliability. The huge network that’s developed around the Impreza in motorsport – particularly rallying – means there is a wealth of supporting knowledge and technology. Depending on spec, over 300 bhp is available straight out of the donor Subaru, and the tuning potential beyond that is mind boggling.

majority of the structure. At the back, the rear suspension bolts directly onto the tub, while, at the front, a tubular steel subframe carries the suspension mounting points and the engine cross member.

With the basic structure defined, Muir and the team were able to develop the design using finite element analysis. They paid particular attention to high stress areas like the rear strut top mounts. “They’re one of the highest stressed areas in the entire monocoque,” comments Yates. “We worked to a safety factor of six times required strength or above across the entire structure, but that area was one of the biggest

challenges.” The end result is said to be a tremendously stiff, yet lightweight structure.

Although the Murtaya predominantly uses Impreza parts, the chassis geometry was all determined in-house. The suspension struts are a bespoke Adrenaline design, but production is outsourced to a specialist manufacturer. The wheelbase is 100 mm shorter than the donor Impreza and the car runs entirely its own geometry in terms of camber, castor and toe. “Another benefit of the Murtaya design,” comments Yates, “is that the centre of gravity is significantly lower than the donor Subaru’s and we have an inherently better roll centre location. The

COMPUTER SIMULATION As Yates recalls, the process of developing a new platform for this four wheel drive hardware began with computer simulation.

“We started out using Catia V5 as the software platform for the design of the car,” he says. “We cloud modelled an entire Impreza drivetrain, which gave us incredibly accurate measurements – to within microns – for all key components, mounting surfaces and packaging requirements.” As Muir then set to work with Catia to establish the basic layout and geometry, the design started to take shape with a composite monocoque forming the

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ABOVE The Murtaya combines power, light weight and four wheel drive in the one potent package (Photos: Duncan Jeggo) BELOW Murtaya has developed a number of platforms for the popular Subaru Impreza hardware. The rally/race prototype is seen on the left. The road specification kit utilises a modular build concept to help owners spread costs

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NEW CAR

HIGH car resists body roll very well, even to the point where we run no anti-roll bar whatsoever on the rear of the road cars and only a very soft unit on the front.”

The team developed the suspension geometry through a mixture of analytical methods and track testing, and Yates is keen to emphasise the importance of driver involvement: “The best theoretical set-up is not always the best solution dynamically.

We needed something that offered lots of feel and gave the driver plenty of confidence. We’ve managed to improve the weight distribution so the inherent understeer which is evident in production Imprezas has been pretty much eliminated.

We do build the road cars with a small degree of understeer as a factory set-up, but that can be dialled out very easily with slight geometry alterations.”

HITTING THE STAGES Initially the team concentrated on building a road-going variant, but the intention was always to produce competition versions for rallying, speed events and circuit racing.

The first Murtaya rally car was built towards the end of 2007 and Adrenaline recently

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BELOW The design was developed with extensive use of finite element analysis

the cornering forces aren’t so high, but the actual impacts are much, much greater. So the way you approach the design and the way you look to address those issues varies quite a lot from discipline to discipline.”

The basic monocoque, barring minor material changes, stays almost identical over all three versions. The main differences centre on the front subframe and the roll structure, with a comprehensive multi-point cage put into the race and rally cars.

There’s also some additional triangulation and different gauge materials used in the front subframe. The strut top plates get reinforced significantly for the competition variants. The area where the subframe triangulates back into the monocoque at the front bulkhead receives considerably more triangulation and bigger load

in certain areas, and small patches of epoxy-based resin are also used to reinforce localised stress points. This results in a strong but light structure. In road trim the GRP-bodied Murtaya’s rolling wet weight is typically around 900 kg. In comparison, the Subaru Impreza, from which it takes its powerplant and 4WD drive train, comes in at nearly half a ton heavier.

Initially the company manufactured everything in-house, but as demand for the cars grew it took the decision to sub-contract the monocoque production. “We actually use a company based in Dorset called Norco which specialises in speed boats. The move was made purely on the basis that we would otherwise have needed to invest huge amounts of money to scale up to the production levels required,” says Yates.

'TOO FAST TO RACE'

We cloud modelled an entire Impreza drivetrain, which gave us incredibly accurate measurements

acquired MSA approval for it under the K37 classification as a Category 2 Specialist Rally Car. Now, a fixed head circuit racing variant is set to complete the line up.

All three platforms use composite materials, but the exact composition varies depending on the application. “The main difference is the loadings and the abuse that the car is going to take,” explains Yates. “A race car generates huge levels of lateral force from the slick tyres and the suspension geometry that you run, so that creates one specific set of loadings that you have to create solutions for. A rally car takes an entirely different type of loading, where

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spreading plates.

The standard road car tub is predominantly glass-reinforced plastic (GRP), using a polyester-based resin, handlaid into the moulds and heat cured. Where the rules allow, the competition variants can be produced in carbon fibre. This entails a slightly different approach, but they’re still hand-laid, then baked, not vacuum formed.

Although the carbon fibre and GRP cars both use those fibres as the basis of their construction, there are a lot of other materials used in different parts of the car.

For example, high density foam core sections are used to provide extra strength

To showcase its talents, Adrenaline has turned to racing, but it wasn’t easy. “It’s been quite difficult to find a race series that will welcome us with open arms,” comments Yates. “There are a number of race series that we’ve been invited to compete in, only to have that withdrawn when we put an entry in.” An email from one championship organiser even stated that they feared the Murtaya would dominate to the detriment of their TV coverage. This of course proved to be a blessing in disguise for the car which has since unofficially adopted the old Group B slogan: ‘Too fast to race’.

Eventually, however, Adrenaline did find championships that would welcome the car. “There are a number of series – Britcar in particular – that allow us to innovate a

April 09

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NEW CAR MURTAYA

little bit and do something different,” says Yates. “We’re going to contest them this year and see how the car is received.”

The car they’re using was originally built as the first Murtaya rally car. It did a lot of development and testing although homologation issues [since resolved] mean it was never actually used in anger. During the summer of 2008, Yates explains, the team was approached by an ambitious young racing driver by the name of James Harrison: “He liked the car and thought it would be competitive so we struck a deal with him to test the car in 2008 and run in the championship in 2009. Essentially we’re taking the rally car and making some minor modifications to get it out on the circuit at minimum cost in the first year. Although we’re in a serious championship that’s used to big expenditure, we’re doing it on a very tight budget. The idea is that we’ll do a lot of testing and development for the forthcoming circuit racers this year, before a full factory-backed effort in 2010.”

BRITCAR CONTENDER The Britcar contender uses a standard Impreza Turbo engine coupled to a standard Subaru gearbox. The only significant powertrain modification is a Simtek ECU, which releases more power and allows fine tuning of the power delivery. Suspension, as

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with all competition Murtayas, comes from Exe-tc. This is a small British company that has won in everything from Formula One to Moto GP and is a veteran of several long stints in the World Rally Championship, including countless event and championship wins with Subaru and Citroen. “We’ve done spring and damper setup with Exe-tc using

The centre of gravity is significantly lower than on the donor Subaru

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BELOW A lightweight sprint version will see service for the first time this season

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ABOVE Murtaya has MSA approval for its rally car variant

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April 09

their strut bodies and bespoke internals and we’re really pleased with the result,” comments Yates.

A competition braking system completes the conversion with 360 mm vented discs gripped by six pot callipers at the front and four pot units at the back, running on 330 mm vented discs. The AMS branded callipers are manufactured for Adrenaline by Hi-Spec. An adjustable bias bar distributes the force between the two. Unlike the rally car, where it is bypassed to prevent interference with the vacuum supply for the anti-lag system, the circuit racer maintains the original Subaru’s servo assistance.

The car in question is just one of a growing number of competition Murtayas which are emerging currently. Former MSA Asphalt Rally Champion Steve Simpson is due to be contesting this year’s British tarmac rally championship in a TEG Sport-built car, and there are examples heading for domestic gravel championships in both Scotland and New Zealand. On the other side of the world, one customer in Canada is working on a 650 bhp carbon fibre-bodied car for local motorsport events. Add to that several owners looking to contest national level sprints and hillclimbs in the UK, and the diary is starting to look distinctly full for Adrenaline Motorsport. It may still be a relative newcomer but the Murtaya, it seems, is well on the way to establishing that niche. RT

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