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Mazda details diesel prototype at Daytona test

Diesel has without a doubt become the dominant fuel in the modern era of endurance racing. The 24 Hours of Le Mans has been won under diesel power for the past eight years running, as has every race in the FIA World Endurance Championship since its inauguration in 2012. Yet there will only be one diesel prototype entered in the top tier of the new Tudor United SportsCar Championship this year, and it belongs to Mazda.
The last Japanese manufacturer to win at Le Mans outright, Mazda has been gradually working its way back up the endurance racing ladder once again, following the example set by Audi with diesel power. Last year it campaigned a competition-spec Mazda6 Skyactiv-D in the GX class of the Grand-Am series, but rather than simply port over the existing racer into the new series, it's fielding a new prototype instead, just as it promised a couple of months ago. And now that prototype has hit the track for the first time, prompting Mazda to release its basic specs for the first time.
Tentatively referred to simply as the 2014 Mazda Prototype, the purpose-built racecar is testing this weekend in the Roar Before the 24, the official test session at Daytona that kicks off the racing season. It packs a 2.2-liter SkyActiv-D engine that's based heavily on the production version but tuned to produce 450 horsepower and 580 pound-feet of torque in race trim. Power is channeled through a six-speed sequential transmission from Xtrac, carbon brakes from AP and 18-inch racing slicks from Continental. With the Daytona-spec aero setup, it'll top out at around 186 miles per hour.

Junkyard Gem: 1981 Mazda RX-7

The first-generation Mazda RX-7 was sold for the 1978 through 1985 model years, and for decades you'd see and hear these nimble little sports cars buzzing around American streets. Then, well, the apex seals went out, or owners tired of a 2,400-pound car that drank fuel like an Eldorado, or the floor pans were eaten by the Rust Monster... and then nearly all of them were gone. Enough of them remain, however, for a steady trickle to show up with depressing regularity in self-service wrecking yards. Here's a pretty solid '81 that I found in a Denver yard last month. The 12A Wankel engine in this car made 100 hp and 105 lb-ft of torque, which was very good for 1981 (considering that you could buy a new Camaro with a 115-horsepower V8 that year). The $9,385 RX-7 looked like an especially good value when compared to, say, the $11,299 Datsun 280ZX or the $8,997 Fiat 124 Sport Spider, being much lighter on its feet than the former and much quicker than the latter. View 12 Photos If you have ever considered getting one of these cars, move fast before all the restorable ones are gone! Auto News Mazda Automotive History mazda rx-7

Mazda Skyactiv-X Review | The revolution begins with a squeeze-bang

The matte black Skyactiv-X prototype looks like a rough Mazda3, perhaps reconstructed after a bad wreck by an over-enthusiastic owner of a spot welder and lots of gaffers' tape. Ribbed ducts poke out of the dash sending two breaths of conditioned air to no one in particular. Even its revolutionary engine, the thing we're here to experience, is entombed in a massive, nondescript cover to mask its unseemly noises. It's a wild, strange way to meet a very unconventional vehicle that promises diesel-like fuel economy, a wide torque band, and an exotic method for burning less gas than ever before. It takes a few hours for Mazda's engineers to explain the fundamental principles of operation. For more detail, read our Skyactiv-X Spark Controlled Compression Ignition explainer, but here's a very brief overview. Skyactiv-X marries some traditional gasoline engine characteristics with a novel form of compression ignition called SPCCI. The key for Skyactiv-X is to use very high compression in the cylinder and an extremely lean fuel-air mixture. Squeezed right to the cusp of getting hot enough to blow up all on its own (which is very hard to predict), a squirt of extra gas and a spark interject to cross that compression-ignition threshold in a controlled and predictable manner. See the animation below: That takes a few essential components to get just right. One is a massive amount of computer processing power and some pressure sensors in the individual cylinders, because the ambient conditions change how and when these things happen. Skyactiv-X uses a clutched supercharger to pump in additional air when needed to nail the mixture precisely, and high-pressure injectors to get the low ratios of fuel to disperse properly in the chamber. And since it operates like a conventional gasoline engine sometimes, it uses valve timing to lower the very high compression ratio so it doesn't reach combustion ignition in that mode. In practice, the Skyactiv-X runs in compression ignition mode most of the time. In practical terms, that means it drives like a torquey gasoline Skyactiv engine. The torque curve is broad and flat — diesel-like in that respect. That also means it can get away with using a six-speed transmission and a lower final drive for better response. There's enough grunt and economy together that Mazda can let the engine spin faster — at 60 mph, it's running at roughly 1,000 more RPM than a similar gas engine, with greater efficiency.