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"  Jaguar. Just saying the name brings chills to even the most hardened of shade-tree mechanics. The beauty and charisma of the marque&amp;#039;s products are nearly matched by the complexity of the cars&amp;#039; mechanicals. But sometimes, there&amp;#039;s a design problem that threatens to overshadow Jag&amp;#039;s tasty rides. One incident stands out for its severity as well as its simplicity\u2014the failure of its Nikasil-lined V8 engines.  In the early nineties, Jaguar recognized that its long-in-the-tooth but much-loved inline six\u2014which traces its lineage to 1949\u2014was finally due for replacement. To compete with other luxury brands, the new engine would be an aluminum V8 and supercharged for the Jaguar XJR to produce 370 hp. Because aluminum is too soft to withstand the action of the piston rings scraping up and down the cylinders, most aluminum engines include iron liners or sleeves pressed into the cylinder bores. But Jaguar didn&amp;#039;t use iron liners. Instead, the plan called for lining the aluminum bores with a material called Nikasil. Nikasil is an ultra-hard, friction-reducing material invented by Mahle in 1967. It&amp;#039;s a mixture of nickel, silicon and carbon and is used primarily as a sort of spray-in cylinder liner, applied by electroplating it to a prepared metallic surface and then honing it. Think of it as Teflon for engines. Nikasil saw some success in racing, and it remains a good choice when weight and performance are the most important factors. The legendary Porsche 917 used Nikasil as a cylinder-lining material; the 911 still uses it, as do many sport motorcycles. However, when Jaguar decided to go with Nikasil, things didn&amp;#039;t work out quite so well. After the new engine went into production for the 1998 model year, spotty reports of odd engine failures began to trickle in. Slowly, almost imperceptibly, the engines would lose power: They&amp;#039;d take longer and longer to crank to a start in the morning and eventually they simply would not start. In short order the cause was found to be low compression in the cylinders; an inspection of the cylinder walls unearthed the problem. The Nikasil liner was failing, which allowed the rings to score the cylinder walls and reduced compression. The question was: Why? There was a two-part recipe for failure. The first ingredient was sulfur. Sulfur levels in the world&amp;#039;s fuel supply varied widely during the time Jaguar produced this engine. England, Jaguar&amp;#039;s home, had a fuel mix with very low sulfur levels, so Jaguar didn&amp;#039;t encounter the problem during design and development. But once the engines reached other parts of the globe with higher concentrations of the element in their gas, the trouble started. Sulfur can do funny things to an engine&amp;#039;s intake system. If the conditions aren&amp;#039;t just right, sulfur combines with ambient molecules to form sulfuric acid, commonly known as battery acid. Sulfuric acid in an engine will attack and corrode any surface it touches, though iron is considerably more resistant to corrosion than Nikasil is. Still, Porsche has long used Nikasil to line its aluminum cylinders, so why did Jaguar have a problem? Enter the second ingredient\u2014heat or, rather, the lack of it. For performance, fuel-economy and emissions reasons, the Jag V8 ran cooler than the Porsche. That lower temperature plus sulfur in the fuel allowed the formation of sulfuric acid.  Jaguar soon began replacing entire engines. By the next year, engineers had changed the design to include traditional steel liners. Since Jaguar&amp;#039;s troubles, though, automakers have made great strides in liner-free aluminum-engine design. Ford recently released its highest-performance Mustang engine ever, with a plasma-transferred wire-arc cylinder liner made of an iron oxide, which saves 8.5 pounds and improves overall performance. As the industry begins to focus on weight reduction and high-performance small engines, such technology will trickle down to more modest cars. When it does, let&amp;#039;s just hope the designs have been thoroughly tested against the kind of weird occurrences that doomed Jaguar&amp;#039;s Nikasil-lined V8s. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/cars/a6643/top-automotive-engineering-failures-jaguar-nikasil-v8/>