Carbon Conqueror - 2013 Mazda 6 Skyactiv-D GX

At the beginning of the decade, the car industry at large was faced with an ever-growing problem. With public awareness and concern about the effects of car usage on the environment on the rise, more and more manufacturers were forced to face the facts. This new focus on lowering emissions moved the vast majority to adopt the practice of downsizing, creating ever smaller turbocharged engines to replace their larger naturally aspirated predecessors.

However, there was another way. As environmental agencies, scientists and governments alike pointed towards carbon-dioxide (CO2) as the biggest “greenhouse gas”, the petrol engine seemed to under threat. Instead of wasting huge amounts of money in research and development to solve a seemingly incurable problem, several companies put renewed focus on the diesel engine.

Volkswagen was one of the most prominent proponents of the diesel engine.

Thanks to its relatively low CO2-emissions, the diesel was seen as the savior of the internal combustion engine. Advances in emissions controls like particulate filters, improved drivability and reduced noise made the oil burners a viable alternative.

Governments around the world realized the same, and introduced tax cuts and stimulus packages to get the public to buy diesel cars en masse. Some countries even went as far to offer compensation for those willing to trade in their petrol car for a cleaner diesel example. European manufacturers like PSA, VAG, Renault, Daimler-Benz and BMW happily profited from the new political climate, as they were already deeply invested in the lucrative European diesel market.

Mazda's first diesel vehicle, the 1970 E2500 truck.

One manufacturer which had failed to secure a large share of the market was Japanese auto maker Mazda. On the old continent, the Japanese firms were never really taken seriously when it came to diesels, as more refined designs from Mercedes-Benz, Volkswagen and Peugeot had taken preference.

In developing countries however, the Japanese diesel engine in its many forms had become a vital part of society, powering along most of the so-called Second and Third World. As such, Mazda was no stranger to diesel engines. After using a series of British-designed Perkins units starting as early as 1970, the company finally started developing in-house designs at the end of the decade.

The Skyactiv-D concept was intended to break Mazda into a brand new market.

The jump to the European continent didn’t happen in earnest until the late 1980’s, including the unusual Comprex wave-supercharged 2.0L RF engine. Predictably, Mazda found itself fighting a losing war in the conservative and largely gridlocked European market. With the advent of favorable diesel laws in the late-2000’s though, a new market presented itself.

Following in the footsteps of diesel kings Volkswagen, Mazda prepared to break ground in the unlikeliest of countries; the gasoline-obsessed United States of America, which was experiencing a period of high fuel prices.

The Mazda 6 Skyactiv-D GX at the 2012 Los Angeles Auto International Show.

VW was blazing a profitable trail with its incessant Clean Diesel campaign, which inspired Mazda to follow suit. In order to win over the Americans, the Japanese firm constructed the SH Skyactiv-D engine, a highly refined 2.2L four cylinder diesel with an innovative light build, quiet demeanor and very favorable fuel economy.

The engine was first presented at the 2009 Tokyo Motor Show, and met with critical acclaim following its launch in the flagship Mazda 6 in 2012. The engine being a minor hit was all well and good, but something needed to be done force a major breakthrough.

Despite numerous technical advances over the years, most people still though of diesel engines as dirty, noisy, rough-running agricultural machinery. Diesel really needed to be made sexy to appeal to more consumers.

The Grand Am RX-8 was taken as the base for the new diesel racer.

Again, Mazda seemingly took inspiration from the biggest name in the business. Adhering to the time-tried adage Win on Sunday, sell on Monday, the company decided to enter motorsport with their Skyactiv-D engine.

Volkswagen’s subsidiary Audi had already proven the diesel’s worth in competition at Le Mans followed by French auto giant Peugeot, with VAG problem child SEAT successfully taking diesel to the World Touring Car Championship. Keeping these examples in mind, Mazda knew it could win big with a racing diesel.

To this end, Mazda elected revamp an existing campaign. Through race engineering firm SpeedSource, the company had been running a 20B-powered version of the RX-8 in the Rolex Sports Car Series, the premier category sanctioned by the Grand Am Road Racing Association. For 2013, Grand Am added the Grand eXperimental class, a category intended to showcase alternative drivetrain technologies in the traditionally V8-dominated series.

To save precious time and money, Mazda again contracted SpeedSource to base the new GX-car around the existing tubular steel spaceframe chassis previously used for the RX-8. In order to accommodate the longer silhouette of the 6 model, the chassis was stretched by six inches (15 cm). Otherwise, the car was left alone. The 6 bodywork was made exclusively out of carbon fiber to save weight.

Fitted as far back in the chassis as possible was a sequential bi-turbo version of the Skyactiv-D straight four. Mazda’s American chief of motorsport operations John Doonan stressed most of the powerplant was interchangeable with the standard motor, with only a few strengthened parts used to increase longevity.

"We’re up to over 250 part numbers straight out of the road-car engine that are in the race engine. It’s about 63 percent of the motor. The crankshaft, rods, pistons, and valves are all racing-based for material changes. Those pieces that have been changed have had that done only for durability and materials."

John Doonan.

In addition to uprated running gear and the impressive turbo setup, the engine benefited from specialist fuel supplied by Dynamic Fuel. The company had developed a renewable synthetic fuel by reusing fats, oils and other combustible waste products from the meat-processing industry.

Using this organic go-juice, Mazda-engineers saw engine temperatures drop by 10 to 37.7 degrees Celsius (50-100 Fahrenheit). More importantly, the Skyactiv design principles combined with the fuel negated the use of a heavy power-sapping particulate filter, and virtually eliminated the infamous black smoke.

Power was also marginally increased by three to four horsepower, resulting in a grand total of 380 horsepower and a monumental 610 nm (450 ft lbs) of torque. Naturally, both figures were attained at dramatically low revs. Max power was reached at just 4800 rpm, with max torque spreading out quite nicely between 3750 and 4750 rpm. The engine’s rev limiter cut in at 5200, meaning full power was on throughout most of the active rev range.

Owing to the chassis’ RX-8 origins, the engine was placed longitudinally, driving the rear wheels through an EMCO 46P1 6-speed sequential transaxle. Dual wishbones were fitted on all four corners, and Alcon steel racing brakes were on board to stop all of 1,111 kilo (2,449 lbs). A basic aero package featuring a large rear wing and front splitter provided much-needed downforce.

The 6 GX in a simple black testing livery, Daytona 2013

Three cars were finished in time for the first round of the Rolex Sportscar Series: the prestigious 24 Hours of Daytona. Car #70 was the de facto factory car, running in Mazda’s familiar deep red racing color and featuring Silvain Tremblay (CAN), Tom Long (USA), James Hinchcliffe (CDN), Marino Franchitti (GB) and Jonathan Bomarito (USA) on the roster.

The two other machines were supplied to customer outfits Visit Florida Racing and Freedom Motorsport. The yellow and red #00 VFR car enjoyed the services of Mazda driver development graduates Joel Miller (USA), Tristan Nunez (USA), Spencer Pigot (USA), and Tristan Vautier (FRA), who were joined by highly decorated veteran Yojiro Terada (JAP). Terada had been a Mazda factory racer since the early 1970’s, taking 29 Le Mans starts and four class wins. The third and final entry was the #25 green and white Freedom Motorsport car, piloted by Derek Whitis (USA), Andrew Carbonell (USA) and Rhett O’Doski (USA).

All three Mazda entries side by side.

With the GX-class still in its infancy, the three Mazda’s were only challenged by three examples of the BGB Motorsports-prepared Porsche Cayman GX, which were infused with copious amounts of 997 GT3 DNA and given a direct injection 3.8L flat-six engine.

In qualifying the Porsche’s proved too strong for the Mazda’s, with the Napleton Racing and BGB Motorsports entries taking first and second in GX. Following in third was the Visit Florida Racing Mazda, fourth the Mazdaspeed car, and fifth the Bullet Racing Porsche, leaving the Freedom Motorsport Mazda 57th and last on the overall grid.

“The brakes are phenomenal, the transmission is excellent. The big difference, of course, is the engine, which revs so low and yet is still so torquey. It’s a big adjustment. And we’ve come from driving what is essentially the loudest engine ever produced by man (the rotary) to one of the quietest ones. You have to rely a lot more on the shift lights on the dash because you cannot hear the motor as much, especially out on the banking with all the wind noise.”

James Hinchcliffe.

Sadly the long-anticipated run at Daytona was tragically cut short. One after another the three Skyactiv-D racers dropped out with burnt out pistons. As it turned out, a 25-cent nut had vibrated itself out of a fuel line, leading to fuel starvation and overheating, quickly killing the engines.

At the Circuit of the Americas in Austin, the GX-field reverted to three cars in total. With only the BGB Motorsports Cayman to contend with, the Mazdaspeed car and Visit Florida Racing machine stood a real chance of scoring the first diesel-powered victory in Grand Am. Unfortunately Tristan Vautier and Tom Long lost out to Spencer Pumpelly (USA), Jeff Mosing (USA) and Jim Norman (USA) in the Porsche. Sadly, the second Mazda retired on lap 39 with a broken driveshaft.

Tremblay / Long, Circuit of the Americas 2013.

The third round of the season took place at Barber Motorsports Park in Birmingham, Alabama. For the first time, the diesels managed to out-qualify the single Porsche. Tom Long and Sylvain Tremblay were given the honor of starting from the first diesel pole position in GX.

The high spirits from qualifying were stifled on race day however, as the Mazdaspeed car dropped out after 51 laps. Visit Florida Racing with Joel Miller and Tristan Nunez soldiered on, but finished three laps behind the BGB Motorsport Porsche.

Mazda's fortunes turned around at Road Atlanta.

The BGB Motorsports Porsche was back on top in qualifying at the swooping Road Atlanta circuit. Tremblay and Long were second fastest in #70, with Joel Miller and Andrew Carbonell close last after failing to set a time.

The Visit Florida machine was able to best the Porsche this time, and took the lead in GX. Mazdaspeed dropped back to four laps behind the other two, but Miller and Carbonell were able to fend off the quick Cayman to take Mazda’s first win in GX. In the process they had secured the first victory for a diesel-powered car in Grand Am after only four races.

Miller/Carbonell took the checkered flag for Mazda.

For the fifth round at Detroit, the Mazdaspeed car once again took pole in GX, this time by 1.523 seconds over the Porsche. Ironically the red car would again be the one to fail to finish, leaving the yellow and red of Visit Florida Racing to take the win ahead of the Cayman.

The pattern of two cars finishing and one retiring continued at Mid Ohio, where the Visit Florida Racing machine gave up the ghost on lap 66. Because of this the #70 Mazdaspeed 6 was able to take its maiden win.

Round 7 of the championship took place at the grueling high-speed Watkins Glen course. Spread out over 6 hours, the race would once gain test the strength of Mazda’s resolve. More than anything, the company hoped to bring two cars to the finish for the first time.

Sadly this was not the case. Tremblay and Long in the Mazdaspeed car were the second entry to retire, having completed only 58 laps. BGB Motorsports followed them out of the race 29 laps later, meaning Miller, Nunez and Yojiro Terada were left without any competition to sail to Mazda’s fourth victory of the season.

Pitstop for #00 Visit Florida Racing, 2013 Watkins Glen 6 Hours.

At the famous Indianapolis Motor Speedway, Mazda finally got its wish of bringing both cars to the finish. Split by the BGB Porsche, #70 took the win in front of #00 in 3rd. At long last, both diesels had completed a race distance.

Road America near Elkhart Lake, Wisconsin was the venue for the ninth round of the Rolex Sports Car Series. Business resumed as usual, with Mazdaspeed retiring with mechanical woes on lap 55. Visit Florida then took the win in front of BGB.

Publicity shot comparing the Mazda 6 Skyactiv-D GX to the 1952 Cummins Diesel Special Indycar.

At Kansas Speedway, Visit Florida beat BGB to another first place finish by a commanding 6 laps. Ironically the junior team car appeared to be the dominant one, as the red factory-sponsored machine again failed to finish. The 6 Skyactiv-D was by now the car to beat in the still tiny GX-class

Laguna Seca saw the initiative shift back to Mazdaspeed, with Tremblay/Long pipping the BGB Porsche to the win. Visit Florida Racing encountered trouble along the way this time, and came in dead last, 20 laps down. A new GX-car, the SDR/Lotus Racing Evora of Scott Dollahite (USA) and Jeff Mosing failed to impress, finishing two laps ahead of the stricken #00 Mazda.

Mazdaspeed battling its archnemesis, the BGB Motorsports Porsche Cayman GX.

The season finale at Lime Rock Park near Lakeville, Connecticut was not only the last race of the season, but also the last for the Rolex Sports Car Series. The Grand Am Road Racing Association had entered into a merger with the American Le Mans Series. Part of this merger was the consolidation of the series into four different classes, which excluded GX.

Mazdaspeed took the the final win of the short-lived GX class in front of BGB Motorsports. Visit Florida Racing sadly missed out on a farewell tour of the podium by going out on lap 133. The late-blooming Lotus Evora disappointed again by succumbing to accident damage on the opening lap.

The Mazda 6 Skyactiv-D GX was a daring experiment by an entrepreneurial manufacturer looking to get a foothold on an unexplored market. In the face of ever more strict emissions regulations in the war on CO2, Mazda opted to develop the cleanest diesel engine they could think of.

Looking to follow in the rather large footsteps left by Volkswagen, Mazda wanted to assert itself as a diesel manufacturer in the gasoline-infused American market. They deemed the best means of promotion to be the noble art of motorsport, and managed to build a competitive diesel racer on their first try.

With nine out of twelve rounds won, Mazda’s GX campaign was a resounding success. However, with the GX-class axed for 2014, the company was forced to take to the big leagues with a diesel-powered LMP2 in the new IMSA Weathertech Sportscar Championship.

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