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Looking Into a 617hp Brazilian Nextel Cup Motor

Full Brazilian

By Stephen Kim

NASCAR is turning into NASA CAR, but no one seems to care. In an era when Toyotas have pushrods and Chevys mount their distributors up front, all four manufacturers now field clean-sheet engine platforms that are designed specifically for competition and are completely unrelated to any production motor. This shift in engine philosophy means that the final vestiges of production-car hardware have been entirely eradicated from stock car racing. While the cutting-edge technology used in these motors—such as compacted graphite iron blocks, valvespring oil squirters, and cylinder heads whittled down like Renaissance sculptures to reduce mass—is impressive, they look like something heisted straight out of the Jet Propulsion Laboratory. Consequently, the average enthusiast can hardly relate to them, which makes the concept of racing on Sunday and selling on Monday a history lesson.

What would make things a heck of a lot more interesting for car guys is if LS1s, mod motors, and new-age Hemis duked it out every weekend, but since NASCAR's fan base is too mainstream to make a big stink about it, we're screwed. Interestingly enough, there is land where stock cars actually race with stock-car engines—GM LS3s to be exact—that harkens back to the glory days of 426 Hemis and Ford 427 Cammers. You just have to venture south of the equator to find it.

Brazil's Copa Nextel (Nextel Cup), the nation's premiere stock car series, pits rear-drive Chevys and Peugeots against each other at various road-course venues throughout the country. Like NASCAR Sprint Cup, the series has transitioned from production-car chassis to tube frames to improve safety and level the playing field. Unlike Sprint Cup, however, Copa Nextel stock cars are powered by ethanol-burning, 416ci GM LS3s that produce 617 hp and use stock blocks, cylinder heads, and intake manifolds. In other words, every single part on these motors will bolt right up to the LS3 in your Camaro or Corvette. What a concept. In an effort to promote parity and keep costs under control, the sanctioning body supplies identical spec motors to each team, and they are built by a single engine shop—Texas-based Mast Motorsports. Intrigued by what it takes to R&D a Brazilian-American hybrid of a stock-car motor, we followed along as Mast Motorsports put one together. To make things more interesting, we dyno'd the motor on both ethanol and 93-octane pump gas. While the 416 made 26 more horsepower on ethanol than on gasoline, it's not for the reasons you might expect, so keep reading before you contemplate an E85 conversion for your street machine.

Design Goals

Copa Nextel organizers aren't coy about the fact that Brazil isn't a wealthy country, and limiting costs is paramount in order to attract enough teams to fill the grid of 34 cars. The series launched an all-new chassis in 2009, but the engines for that season were carbureted, gasoline-burning, Chrysler-based 480hp small-blocks carried over from the previous-generation chassis. Looking to make the racing action more exciting and the technology more contemporary, the series wanted to add a big-time boost in power while also switching to EFI. Furthermore, since Brazil is home of the world's largest fleet of flex-fuel vehicles, it only made sense for its most popular form of racing to adapt ethanol as well. In stark contrast to the $75,000 it costs to develop and build a NASCAR Sprint Cup motor, the Copa Nextel series set a strict maximum budget of $15,000 per engine. Thanks to its low mass, outstanding power potential, compact size, and cheap and readily available parts, the LS-series small-block was the perfect solution. "The horsepower target was set at 600, since that's what the chassis and transmissions in these cars were designed to handle. The sanctioning body's top priorities were reliability and keeping costs down, but they didn't have any kind of displacement limit," explains Horace Mast of Mast Motorsports. "This helped tremendously in meeting their objectives, since it allowed us to build a 416ci motor that only needs to turn 6,400 rpm to meet their power goal. The extra cubic inches take a lot of stress off of the valvetrain, which is extremely important in a road-race application."

Replacing engines after every round of competition is far too costly, so the Copa Nextel series needed a package that would last the entire season. This is no small feat, as the cars log a total of 2,800 total miles throughout the course of a 12-race season. The 17 teams are issued a primary motor and backup motor for each of their two cars. At the halfway point in the season, all teams send their engines to the sanctioning body, where they are inspected, dyno'd tested to check their health, and refreshed as necessary. Furthermore, the top five finishers of each event are subject to an additional inspection following every race to ensure their motors haven't been modified in any way. While the bearings are checked for wear, Mast says that the rotating assemblies, rings, and valvesprings should last the entire season.

Short-Block

The grueling durability requirements of the Copa Nextel series would suggest that an ultra-exotic bottom end is a must, but surprisingly, most of the short-block components can be ordered straight out of the Summit catalog. In the quest for cheap and lightweight cubic inches, a 4.065-inch bore GM LS3 block was the natural choice, which Mast finish-hones to 4.070 inches. Combined with a 4.000-inch Callies/Compstar 4340 crank, it nets a 416ci displacement figure that hits a sweet spot on the cubes-per-dollar spectrum. While dropping the same crank in a 4.125-inch-bore LS7 block would yield 427 ci, an LS3 block is half the price at $1,400, making it a much more appealing proposition for the cash-strapped race series. Conversely, a factory 4.000-inch-bore LS2 block would sacrifice 14 ci and only costs $300 less. With the bore and stoke dimensions settled, Mast finished off the rotating assembly with Callies/Compstar 6.125-inch steel rods and 11.3:1 Mahle forged pistons. While the compression ratio may seem conservative, Mast didn't feel the need to raise it any further, as the target horsepower mark had already been reached.


By Stephen Kim
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