To break in the NSX engine, Acura uses a stethoscope

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honda engineer using stethoscope on engine Acura

Now available in the heritage color Indy Yellow Pearl, the 2020 Acura NSX remains just as much of an engineering marvel as on its long-awaited debut day in 2015. And while the street version is an all-wheel-drive hybrid, the reason why the rear-wheel-drive, combustion-only GT3 can also win races is the unique V-6 powering all of Honda’s mid-engine supercars.

nsx internals graphic rendering
Acura
nsx gt3 race car on track side-view
Acura

Turned from a corn field into Honda’s largest engine production site in 1985, the Anna Engine Plant near Dayton, Ohio, is a 2.5-million-square-foot complex counting 3500 employees pushing out 4500 engines on a good day. Yet within this massive facility is a 4000-sq.-ft. workshop where only Acura’s most-experienced master builders have the privilege of hand-building the unique twin-turbo V-6 of the NSX.

Acura says that on average, three decades of experience is required for this job, with an NSX engine being built in around five hours. On the nearby mass-production lines, each engine goes through around 150 employees before its first ignition.

nsx engine on stand
Acura
nsx engine render graphic
Acura

nsx engine render graphic
Acura
nsx engine cover
Acura

Honda’s JNC1 is a special engine designed for this platform only. It is an unusual 75-degree 3.5-liter DOHC V-6, so that its single-scroll turbos can fit under it without raising the top of the engine above the level of the rear tires. It features variable timing control on both cams, along with a forged-steel crank, connecting rods, intake valves, and sodium-filled exhaust valves. The block and cylinder heads are sandcast by Cosworth, while the pistons are cast aluminum, sliding up and down on a plasma-transferred wire arc thermal spray lining.

It’s also a dry-sump with triple-element scavenge pumps, which Acura says not only improves response, but also lets the “bone-stock” GT3 block survive 762 laps at race pace during the 24 Hours of Daytona, covering a total distance of nearly 2713 miles.

yellow 2020 acura nsx on track in motion front three-quarter
Acura
yellow 2020 acura nsx on track in motion rear three-quarter
Acura

For such a task, the NSX engine must be built with the utmost attention to detail. Acura’s experts use GPS-tracked torque tools to make sure all of the JNC1’s 547 fasteners are happy in their slots. They also have three multi-spindle nut runners to level out tensions, after which they run the assembled engines for an hour, listening to foreign noises via a stethoscope at up to 4000 rpm. Having completed the break-in procedure, Acura finishes the build by balancing the engine to spec with different weighted bolts.

Another manufacturer who can claim its road car engine was race-ready from day one is BMW, which supplied McLaren with the mighty S70/2 for the 1992–98 McLaren F1, and 1995’s Le Mans-winning F1 GTR. Interestingly, due to a Formula 1 partnership at the time, Gordon Murray also intended to use a Honda V-12, created by merging two V-6s of the original NSX.

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