By Christopher A. Sawyer
The Virtual Driver

(October 31, 2015) I remember taking my brother Bill for a ride in the NSX a few years after its introduction. On a deserted back road we touched 135 mph in surprising comfort, and not more drama than you might experience taking your family sedan up to the store to get some milk.

Yeah, it was a silly thing to do, and the mid-engined Acura didn’t possess the ultimate ride, handling or feel of some of the established supercars of the time (and make no mistake, the NSX was a supercar), but that didn’t matter. Build quality was above reproach, the climate control kept you warm in the winter and cool in the summer and not the other way around, you could take it to a Honda dealer to get fixed, it didn’t leak or smell like curing fiberglass, and so on.



It, quite honestly, forced every upper tier sports car maker to raise its game, even if the NSX was something of an appliance.

Now, 25 years after the debut of the original, there’s a new Acura NSX. It looks very similar to the concept first shown at the 2012 North American International Auto Show, but is almost completely different than the plan Honda originally had for this car. The second-generation NSX almost reached production as a front-mid-engine, V10-powered coupe with all-wheel drive.

Prototypes were filmed lapping at the Nurburgring in late 2008, but that program died as the global recession took hold. It was replaced by a proposal similar to the original NSX, a mid-engined, all-wheel drive two-seater powered by a hotter version of Honda’s transversely mounted, naturally aspirated 3.5-liter V6. That was the car shown at Detroit. Only it wasn’t enough. To fulfill Honda’s self image needs, the car needed more tech, more power, more stuff.



Powertrain

The first thing to go was a hotter version of the standard-issue Honda 3.5-liter V6. In its place was substituted a 3.5-liter quad cam V6 with a 75-degree bank angle, dry sump lubrication, a pair of single-scroll turbochargers with electronic wastegates, and both direct and port fuel injection. Instead of being mounted transversely, it would be placed longitudinally behind the seats.

The aluminum block is sand cast and the cylinders liners get a thermal spray coating. Compact swing arm-type valve actuators reduce inertia, and variable timing is used on both the intake and exhaust cams.

The nine-speed dual-clutch gearbox has a first gear designed for maximum launch acceleration, seven close ratios to keep the engine in its power band, and an overdrive ninth gear to maximize cruising fuel economy. In order to keep mass low and things compact, the clutch and differential are located side-by-side in the same housing. This moves the center of mass forward, reduces rear axle overhang, and allows better packaging of the direct-drive electric motor sandwiched between the engine and gearbox.

All-wheel drive traction and torque vectoring is provided by the front axle Twin Motor Unit. It can support acceleration up to 120 mph, but provides torque vectoring at all vehicle speeds. Plus, when the selector is placed in Quiet Mode, a light-footed driver can drive the NSX as a front-drive electric vehicle over short distances at speeds up to 40 mph. The Power Drive Unit is located beneath the center console, while the Integrated Power Unit and its high-voltage lithium-ion battery are packaged together and mounted just behind the driver and passenger.

Chassis

As with the original, the NSX is built around an aluminum spaceframe. Only this version has cast pieces at each suspension attachment point that are supported in all three dimensions. Each element is analyzed to optimize both strength and weight, and many of the pieces have custom wall thicknesses that vary from surface to surface.

Two upper and two lower nodes in the front and two nodes in the rear are made from ablation casting, which makes them both strong and malleable. They are designed to progressively crush in an accident while retaining their strength, and the upper nodes act as suspension mounting points.

Steel stampings are used where energy absorption is required, while the A-pillars are formed from ultra-high-strength steel that allows their cross section to be minimized. These pieces are heated then robotically bent, and the parts cooled by water jets. Like the ablation cast nodes, this is a first for this technology in the auto industry. In addition, the floor uses a carbon fiber core forward of the seats, the body panels are a mix of aluminum and composites,  there is the option of a carbon fiber roof panel, the rear trunk is made of sheet molded compound (SMC) plastic, and the fuel door hinge is magnesium. Even with extensive use of lightweight materials, the 2017 NSX weighs 3,803 lb. All the tech used in the powertrain and chassis takes its toll on weight.

Suspension, Steering, Brakes and Tires

The aluminum front suspension use double wishbones with a double ball joint lower arm designed to keep the twin motor drive unit up front from affecting steering feedback. Out back, there’s an aluminum multi-link independent layout. Yes, that’s it. Aluminum multi-link. Nothing too fancy, but nevertheless very rigid to take the expected lateral loads. Finally, the 2017 NSX features third-generation magnetorheological dampers with the widest damping range ever offered, and even faster millisecond response.

Steering is via a dual-pinion electric power system with a rack-mounted power assist motor. It is constant-ratio when the steering is on center, but that gets quicker as the wheel is turned. The combination eliminates any nervousness on the highway, while increasing turn-in response through the corners. The idea was to reduce, if not eliminate, the need to shuffle the wheel or go hand-over-hand in corners in order to keep the driver’s hands on the wheel.

Since it’s a hybrid, the NSX has both friction and regenerative braking systems. The Brembo friction brakes comprise two-piece ventilated 14.5-in. rotors clamped by six-piston monoblock calipers up front, and 14.0-in. ventilated rotors with four-piston monoblock calipers in the rear. Carbon ceramic rotors are available as an option. Openings beneath the car and air ducts in the hollow rear powertrain cradle helps keep the rear brakes cool.

Lightweight “Y” spoke alloy wheels fitted with Continental Conti-Sport Contact 5P tires are fitted front and rear. Not surprisingly, the NSX uses staggered wheel sizes with 245/35ZR-19 wheels and tires up front and 305/30ZR-20s in the rear. These tires are designed for good all-weather traction and long tread life, but those with performance on their minds can order one of the optional wheel and tire packages featuring Michelin Pilot Sport Cup 2 tires.

Driving Modes

With all this tech, you wouldn’t expect the engineers to make it a “set it and forget it” type of car, would you? Of course not. Thus, the 2017 NSX has an Integrated Dynamics System that lets the driver choose from one of four modes: Quiet, Sport, Sport+ and Track. Each choice changes the settings for the steering and brakes (friction and regenerative), throttle, electronic stability control, dampers, engine, gearbox and all-wheel drive system.

It also varies the sound allowed into the cabin through the Active Exhaust Valve and Intake Sound Control. The latter features twin sound pipes with an electronically controlled valve that varies the amount of sound let into the cabin from the engine’s intake plenum. Acura claims a massive 25 dB volumetric sound difference between Quiet and Track modes.

Quiet is for driving on electric power only at lower speeds, and lets the least sound into the cabin. If the power demand is such that the engine is required to start, engine speed is limited to 4,000 rpm, and the ISC’s sound valves are closed. In addition, the transmission’s shift points are altered for greatest efficiency, and the tachometer and central display are bathed in a cool blue color.

Sport uses a higher rev limit and more aggressive throttle map, and the gearbox holds onto each gear longer with higher shift points. More sound from the intake and exhaust is allowed into the cabin, and the stop-start function used in Quiet mode is continued. This is the car’s default setting.

Sport+ adds more aggression to the throttle and the transmission’s shifts up and down the range. The electric motors are used to their maximum under acceleration, and the more assertive yaw control setting is mirrored by more aggressive damping, steering and torque vectoring. Engine sounds are raised yet again, and the central display is bather in red light while the tachometer needle has an aggressive yellow color.

Track is set for at-limit driving on a circuit. Shifts are faster and crisper, the hybrid system and driver aids are more aggressive. More sound enters the cabin, and the braking system is given better pedal feel and response. In addition, the lithium-ion battery’s state-of-charge is set to maintain a consistent torque delivery and response from the torque vectoring system for consistency in lap times. Also, the electronic stability control can be disabled in this mode.

The 2017 NSX will be built at Honda’s Performance Manufacturing Center in Marysville, Ohio, which is manned by nearly 100 associates. This includes 70 skilled manufacturing technicians responsible for body construction, painting, assembly and quality confirmation. The unique twin-turbo V6 engine is built at the engine plant in Anna, Ohio, and is broken in on a dyno before it is mated to the direct drive motor and nine-speed dual-clutch gearbox.

This assembly is dynamically balanced before being shipped to the assembly plant in Marysville. The front-mounted Twin Motor Unit and other hybrid system components are sourced from Japan, which is also where the initial design work took place. This was developed and taken to production by the Acura Design Studio in Los Angeles.

The Virtual Driver