A special manufacturing technique usually reserved for supercars has found its way into the all-new 2019 Nissan Altima 2.5-liter engine.
Inside the four cylinders of the engine block is where Nissan’s state-of-the-art mirror bore process is used to reduce friction and improve efficiency. The treatment, first used in the Nissan GT-R and applied to other specialty models like the Sentra NISMO, helps engines run smoothly by eliminating the need for bulky cylinder liners.
The Decherd assembly line added mirror bore equipment for the launch of the Altima – making it the highest volume application of the technology within Nissan. The team in Decherd assembles an engine every 19 seconds and is capable of building about 1.4 million engines a year.
“Advanced technology like the mirror bore process only makes sense for Nissan if we can offer it to as many customers as possible,” said Jay Boyte, director of engineering at Decherd Powertrain Plant, Nissan North America. “The end result is an innovative and efficient engine made with manufacturing technology usually not available at this volume or price point,” added Boyte.
The process involves spraying and polishing the cylindrical space inside the engine in which the piston moves. During the spraying phase, sparks fly as charged metal wire is blown using gas to atomize the material and coat the inside of the cylinders. The thickness of the coating only needs to be about 200 microns (0.2 millimeters) – or about twice the thickness of a human hair (100 microns) or three times thicker than a grain of salt (60 microns).
In the second stage, a special drill bit is used containing tiny bits of diamonds that were unfit for jewelry. The bit is spun at high speed inside the cylinder to polish the metal until shiny and smooth – giving the process its ‘mirror bore’ name and the cylinder walls a reflective surface. The water applied during this stage is intended to keep the machinery and metals at optimum temperatures and reduce friction.
The Nissan Decherd Powertrain Assembly Plant is the highest-volume engine plant in the U.S., assembling more than 1 million engines annually; and nearly 13 million since opening in 1997. The 1.1 million square-foot facility is located about 90 miles southeast of Nashville and employs 1,700 people.
Nissan Decherd currently assembles engines for Nissan Altima, Maxima, Rogue, Pathfinder, Frontier, TITAN and INFINITI QX60, as well as motors for the all-electric Nissan LEAF.