Super Lightweight Roadster
Despite being only around 10kg heavier than the previous generation, the NC model has been labelled as too big and heavy by purists. In response to this, Mazda performance specialists Good-Win Racing, based in California, have created a project car with the goal of seeing just how light a track focused NC could become.
Owner and founder Brian Goodwin set the targets for power and weight at 300Bhp and 2000lbs (907kg). Since the car would not be raced in a series, there were no rules as to what could be done to achieve these figures. The only limitation was that the car had to be ready to be displayed at the 2010 Miatas at Laguna Seca event, allowing the team just three months to build the car.
AWR Racing were able to provide a bare chassis that had been prepped for racing but never used. It was fully seam welded for strength and already had a full MX-5 Cup rollcage fitted. With the chassis sorted the project was off to a great start and it was time to think about engine options and how best to achieve the desired power output.
It's possible to squeeze in much bigger engines such as a V8 but the larger drivetrain and other reinforcements required went against the lightweight philosophy. The same thinking was applied to turbo and supercharged conversions and a decision was made to keep the car normally aspirated. The plan was to use the Cosworth tuned 2.3 MZR from the Formula Atlantic race series but before such an engine could be sourced plans changed again. Due to another car's fiery retirement from a Thunderhill endurance event, the opportunity to acquire its 2.5 MZR built by MER Racing from Texas was too good to miss.
The engine was originally from a Mazda 3 and was built for the World Challenge series. It featured a 12.5:1 compression ratio and used uprated pistons, race camshafts, stronger valves & springs, and a rev limit of over 8000rpm. The engine was also fitted with a Cosworth intake, Thermal Research side exit exhaust, and controlled by Motec electronics. Once it had been setup and tuned, the engine was producing 270Bhp at the wheels. Almost on target and only a little heavier than the stock 2.0 engine.
The car's suspension uses RX-8 coilovers by Moton with Swift springs, and Delrin bushes in the control arms. Anti-roll bars are changed depending on the track being driven and also use strengthened droplinks. The brakes were upgraded to RX-8 rears and 4-pot front calipers with 13" discs. Despite being larger these brakes actually weighed less than the factory parts thanks to their two-piece design and aluminium calipers.
With the primary aim of weight savings, the interior has been completely stripped out.
All that remains is a Cobra race seat, Sparco steering wheel, adjustable Tilton pedals, AiM digital dash with data logger, aluminium centre switch panel, and a single piece of carbon fibre across the top. Major weight savings were made with replacement body panels and doors. The entire front nose section (bumper, bonnet, and wings) is a single piece of carbon fibre. The hardtop provides aero benefits at high speed on track and is made from carbon fibre, as are the doors. Lightweight Enkei wheels help reduce unsprung weight and there is also a carbon fibre GTC-200 rear wing and aluminium front splitter by AWR Racing.
Brian and the car made it to Laguna in time for the event and at the time the MX-5 weighed under 2100lbs (950kg). You can read more on this car, and Brian's other projects, over on the website: www.goodwinracing.com