1995 Acura NSX/NSX-T Press Kit
The intention in creating the Acura NSX was to produce a hand-built, exotic, mid-engine sports car that would establish entirely new levels of prestige, performance, refinement, driveability and reliability. The NSX is designed to represent an entirely new definition of the exotic sports car.
For the 1995 model year Acura introduces the NSX-T. This model features a removable roof panel to provide the unique thrill of open-top motoring. The goal was to create a different level of excitement and broaden the appeal of the NSX, while maintaining the extremely high levels of performance and sophistication established by the NSX coupe.
As might be expected, creating the NSX-T involved far more than removing the fixed roof and engineering a new removable panel. Engineers extensively reinforced critical areas in the body to ensure that the handling precision and rigidity standards of the coupe were retained as much as possible. Special reinforcements were made in the rocker panels, front and rear bulkheads, floorpan and other vital areas.
All 1995 NSX models also feature a number of technical updates and refinements. Key among these is the optional Formula One-inspired Sport Shift automatic transmission with a unique column-mounted electronic shifter. Unlike other systems, this unit allows the driver to manually select a gear without the drivers hands leaving the steering wheel. This not only adds to the enjoyment of performance driving by allowing the driver to more quickly select a gear, it also enhances safety by allowing the driver to maintain his full attention to the road ahead.
Other innovations include a drive-by-wire throttle system, a new exhaust and muffler configuration for greater efficiency and lower emissions, an OBD-II onboard diagnostic system, improvements in the Traction Control System (TCS) and newly developed fuel injectors. The drive-by-wire system also allows the engineers to lower the threshold at which the Traction Control System will operate, an enhancement to stability and driver control. Beginning this year, all NSX models will feature a standard variable electric power-assisted steering system, a compact and efficient system pioneered in the first-year NSX equipped with the automatic transmission.
All 1995 NSX models meet 1997 federally mandated side impact safety standards.
Concepts and Goals
In designing the original NSX, the engineers formulated a list of attributes the automobile was to possess.
- Top-rank performance equal to or greater than existing exotics.
- Excellentliveability.The NSXhad to be as easy to live with as any other Acura.
- Outstanding handling.
- A high level of comfort and ergonomic design, and low ambient noise level.
- Reliability and durability equal to mass-produced automobiles.
- Lightweight construction throughout.
- Extremely high level of fit, finish and materials.
- Limited production.
- Excellent climate control system that could keep the occupants comfortable under any weather condition.
The NSX achieved all these goals and established itself on a level equal to or greater than existing exotic sports cars. Goals for the NSX-T include all the original attributes of the NSX, plus the intangible excitement of open-air motoring. Priorities include:
- Maintaining body rigidity for excellent handling and precision.
- Maintaining original levels of noise insulation.
- Providing a convenient storage compartment for the roof panel.
- Minimizing wind buffeting at speed
- Providing a security system that functions with the top removed.
The mid-engine, 2-seater NSX is powered by an all-aluminum, 3.0-liter V-6 which produces 270 hp and 210lbs-ft of torque. The normally aspirated engine is equipped with dual overhead cams, four valves per cylinder, a Variable Valve Timing and Lift Electronic Control (VTEC) system, and a Variable Volume Induction System intake configuration. The engine also offers Programmed Fuel Injection (pGM-FI) and a direct ignition system that uses an individual coil mounted atop each spark plug instead of a single coil for the entire system. A 5-speed manual transaxle is standard, with an electronically controlled 4-speed automatic with Formula One-inspired SportShift mode available as optional equipment.
The chassis features all-aluminum construction for light weight. The 4-wheel independent double-wishbone suspension also features aluminum-alloy control arms and hub carriers front and rear, and aluminum subframes for the front and rear suspension. The braking system features ventilated 4-wheel discs front and rear, and an advanced 4-channel Anti-Lock Braking System (ABS).A sophisticated Traction Control System (TCS) has been designed to help limit wheelspin and enhance control on slippery surfaces.
Beginning with the 1995 model year, the NSX is now available in hardtop or removable top models. Both models have been engineered to meet 1997 federal side impact standards.
The NSX engine is an all-aluminum, 90-degree, 3.0-liter (2977cc), dual-overhead-cam, 4-valve-per-cylinder V-6 which produces 270 hp at 7100 rpm when mated to the manual transmission, and 252 hp at 6600 rpm when mated to the automatic transmission. The torque rating is 210Ibs-&at 5300 rpm for both manual and automatic transmissions. The red line of the manual is 8000 rpm, while that of the automatic is 7500 rpm.
An exclusive electronically controlled Variable Valve Timing and Lift Electronic Control (VTEC) system optimizes volumetric efficiency at both high and low engine speeds. A unique Variable Volume Induction System changes the configuration of the intake system with varying engine speeds, working with the VTEC system to broaden the torque curve and increase peak power output.
Engine Block, Cylinder Heads, Crankshaft
To achieve both light weight and durability, the block is made of aluminum alloy with cast-in iron cylinder liners. The crankshaft is a fully counterweighted forged steel unit. The cylinder heads are low-pressure cast aluminum. The combustion chamber is a pent-roof design with generous squish area to promote swirl and enhance combustion efficiency.The spark plug is centrally located for optimum flame propagation, and features a platinum tip for improved durability and longer service life.
Titanium Connecting Rods
The connecting rods are made of a specially patented titanium alloy. While titanium rods are common in Formula One and other race engines, this is the first application of titanium in a production car. Compared to a steel connecting rod for the same engine, these titanium rods each weigh 190 grams less and are significantly stronger.
Variable Valve Timing and Lift Electronic Control (VTEC) System
Without question, the Variable Valve Timing and Lift Electronic Control (VTEC) system is a breakthrough in engine technology. It convincingly solves the age-old trade offs between low-end torque and high-end power.
The heart of the VTEC system is a unique camshaft and rocker arm system. For each cylinders set of two intake (or exhaust) valves, there are three rocker arms and three corresponding lobes on the camshaft. The two outboard lobes each have a profile suited for low- to mid-rpm operation. The third, or center, cam lobe has a dramatically different profile designed for longer duration and higher lift; this lobe profile is designed to optimize breathing and horsepower production at high engine speeds. At low engine rpm, the valves are operated by the outboard lobes. During high-speed operation above 5800 rpm, the VTEC computer sends a signal to a spool valve, which in turn delivers engine oil to small pistons in the rocker arms. Oil pressure causes the pistons to slide, locking all three rocker arms together. Once locked, the rocker arms are forced to follow the center cam lobe, increasing top end performance. The crossover from low lift to high lift occurs in 0.1 seconds and is virtually undetectable to the driver.
Variable Volume Induction System
In addition to VTEC, the NSX engine also uses a Variable Volume Induction System. This system uses a separate intake air plenum, located beneath the main intake manifold. This second plenum is separated from the primary manifold by six butterfly valves, which open between 4600 and 4900 rpm and are actuated by manifold vacuum.
When the valves open, the added volume of the secondary plenum creates a higher resonance frequency, which in turn creates a sonic pressure wave. This sonic pressure wave hits each pair of intake valvesjust as they open, promoting more rapid and complete cylinder filling. This system was designed to work in concert with VTEC to improve both low-end torque and high rpm power.
Programmed Fuel Injection (PGM-FI) ensures that each cylinder receives the precise amount of fuel necessary for the present load and speed conditions. This system has been specially tailored to the unique capabilities of the induction and VTEC systems. For 1995, a new air-assist mechanism has been adopted to aid fuel atomization for better combustion at lowtemperatures.
Onboard Diagnostic System (OBD-II)
A new onboard diagnostic system has been incorporated into the engine management electronics system. This unit records and stores information on transient engine malfunctions. These can be retrieved through the diagnostic port to facilitate maintenance and repair.
For 1995, the NSX receives a new and lighter exhaust system. The catalytic converters are now larger, 1.14liters vs. .96 liters, and have been moved closer to the engine for quicker converter light-up and a consequent reduction in emissions but without any sacrificein power output. The overall weight of the unit has also been reduced by using spherical joints in the exhaust system rather than conventional flexible tubes. Additionally, the shape of the exhaust tip has been revised from an oval shape to a circular shape.
Direct Ignition System
To ensure a hot, stable spark at high rpm operation, the ignition system has a coil mounted atop each spark plug, a design similar to that used in Formula One racing engines.
The standard manual transmission is designed to provide impressive durability, with short shift throws and quick, precise response. Shift throws, in fact, are the shortest of virtually any exotic sports car on the market. A dual-cone synchronizer is used for second gear, for quicker, smoother shifting, and reverse gear is also equipped with synchromesh. For 1995, the second gear ratio has been changed from 1.727:1to 1.800:1- 4.2% lower. This change was made to improve driveability and provide better response.
To handle the high torque and power output of the NSX engine, a twin-disc clutch was developed. The twin-disc design increases the torque capacity of the unit, while retaining a light clutch feel and reducing rotating inertia for quicker throttle response.
Sportshift Automatic Transmission
The optional SportShift 4-speed automatic transmission allows the driver the option of letting the transmission shift automatically in a conventional manner or selecting each gear manually by means of a fingertip control shift lever on the steering column. Inspired by advanced Formula One transmissions, this dual-mode system was created to give the driver of an automatic the same sporting performance feel of a manual. Unlike other similar systems, this one allows the driver to keep both hands on the wheel while selecting a gear. This feature adds to the safety of the vehicle by allowing the driver to concentrate his full attention to the road ahead.
The shift quadrant (PRNDM21) is depicted on the tachometer. SportShift mode is engaged by selecting the M, or manual, position. In M mode, the shift position is illuminated in a window to the right of the shift quadrant. To shift up, the fingertip control lever is moved up, and to shift down, the flipper lever is moved downward. A circuit in the CPU (central processing unit) prevents downshifting that would cause the engine to over-rev.
The automatic is also equipped with a programmed lockup torque converter to improve fuel economy and reduce slippage. In the Sport Shift manual mode, lockup is available in second, third and fourth gear during both acceleration and deceleration.
Torque Reactive Differential
A new torque reactive limited slip differential was developed to minimize spinning the inside wheel on NSX models equipped with the manual transmission. This unit uses a multi-plate clutch and new, helical-type planetary gears. When traveling in a straight, the amount of slip between the rear wheels is controlled by the force of a preset spring-loaded disc imparting a force on the multi-plate clutch. In a tight corner, however, the force of the spring-loaded disc is overridden by the thrust force of the new helical-type planetary gears, thus preventing the inside wheel from spinning and enhancing stability. In testing, this unit improved acceleration time out of a corner by 10%.
Torque Control Differential
The torque control differential employs a multi-plate clutch and planetary gearset to help maintain vehicle stability at speed in crosswinds and when driving over split friction surface conditions. The unit reacts to the rotational difference between the rear wheels and attempts to maintain the same rate of rotation for both wheels.
If the NSX should be forced off the intended direction in a crosswind, the differential will detect the rotational differencebetween the two rear wheels and transfer torque to the slower rotating wheel. This has the effect of directing the car back into the desired path. This differential is on automatic transmission-equipped models only.
Traction Control System (TCS)
The goal of the Traction Control System (TCS) was to minimize rear wheelspin on slippery or uneven road conditions. This unique development was created as a high performance system rather than a pure low-speed traction enhancing device.The TCS uses the wheel-speed sensors of the Anti-Lock Braking System (ABS) to detect the rotational differences between the front and rear wheels as well as a newly developed G-sensor. If the computer determines that the surface is slippery, the CPU (central processing unit) signals are sent to decrease the amount of air and/or fuel delivered to the engine. The driver can elect to disengage the TCS by a switch located on the instrument panel. Refinements in this system increase its sensitivity and lower the threshold at which the TCS is engaged. Using the wheel-speed sensors of the ABS and working in conjunction with the new drive-by-wire throttle system, the TCS engages at impending wheel-slip rather than at the moment of wheel-slip. A new logic circuit also controls stability on sudden deceleration on slippery surfaces.
New for 1995 is a drive-by-wire throttle system. This unit replaces the conventional throttle cable arrangement with an all-electronic system that senses the throttle pedal position and relays that information to a computer. The computer, in turn, performs the actual throttle activation instantaneously. The system works by means of a throttle pedal sensor, a throttle angle sensor, an electronic control unit and a step motor to control throttle opening and provide fail-safe throttle operation. This system also helps to enhance the precision of the cruise control system. In addition to this, all electronic control systems have been streamlined to redcue weight and to improve reliability.
A rigid structure is of paramount importance in a performance car. High rigidity provides a stable platform for proper suspension geometry and alignment, and it makes possible a tight, rattle-free interior. Additionally, central to the goal of performanceis a favorable power-to-weight ratio; a very light car can achieve high performance levels with less horsepower. After an intensive research effort, it was determined that the most efficient way to meet the rigidity and weight targets for the NSX was to build the car exclusively of aluminum.
Using a Cray supercomputer, the engineers performed millions of Finite Element Modeling (FEM) and stress analysis calculations. The result of this research and development effort is a chassis that weighs 210 Kg (462 lbs) with doors, hood and decklids installed- about 40% less than a steel chassis, but with the same rigidity and impact protection. The NSX structure is significantly stiffer than every other competitor currently on the market.
For the 1995 model year, the NSX will be available with a removable top. Both models meet 1997 federal side-impact standards.
To restore rigidity to the body with the roof panel removed, the structural engineers employed extensive reinforcement measures throughout the body. The areas that required reinforcement were a redesigned side sill aluminum extrusion with significantly thicker wall sections, the base of the B-pillar where it joins the rocker panel, a larger rear bulkhead crossbar, a thicker trunk leading edge panel, a reinforcement web in the rear floor cross member, an additional rib in the center rear bulkhead section, a redesigned and thicker walled rear roof rail section, a redesigned front roof rail section with increased wall thickness, a completely redesigned and thicker upper A-pillar, a redesigned and thicker upper dashboard cross-member, and a redesigned front lower floor section with increased wall thickness.
The removable top is made of aluminum for light weight and durability. The roof panel is body-colored and is easily removed by means of two latches located on the left and right side. Its light 8.5 Kg makes it easy to remove and stowaway. A dash indicator light alerts the driver if the latches are not properly closed. Once removed, the panel is stored under the rear glass hatch and the hatch can be locked with a key for security. Since the top has its own storage compartment, it doesn't use any of the available trunk or interior space.In addition, the vehicle security system functions with the top removed as well as in place.
Extruded Aluminum Side Stills
To attain a structure of high rigidity, complex aluminum extrusions were used for the crucial side sills of the unit body. These extrusions, with their carefully braced internal structure, contribute to the extremely high torsional stiffness of the NSX.
For the N5X-T, these side sills received extensive reinforcement. The wall thickness of the vertical center web of the five-sided extrusion was increased from 2 mm to 6 mm. Other wall thicknesses were increased from 2 mm to 5 mm, 3 mm to 6 mm, and 5.5 mm to 6 mm.
Radiused Front Frame Rails
To maximize occupant protection, the front frame rails of the unit body are designed with large-radius curves where they meet the passenger cabin. This design helps to dissipate energy in the event of a collision, spreading out impact loads and diverting them under the passenger cell.
Concept and Goals
The objective was to create an interior that was the sports car equivalent of a jet fighter pilots helmet. The key elements of this concept were unlimited visibility, a feeling of snugness or intimacy with the interior of the vehicle, and the sense that the cockpit and driver were out in the airstream rather than enclosed and isolated from the environment. To achieve this feeling, the seating space for the driver and passenger was designed to fit snugly at the hips and flow outward and upward to provide ample space for the head and shoulders.
Seating Position and Visibility
A low seating position contributes to a low center of gravity and helps to reduce the frontal area for improved aerodynamics. Ordinarily, a low hip-point would impart to the driver the feeling of being buried in the interior and create a claustrophobic feeling. To avoid this, the body engineers created a very low cowl section which allowed them to lower the height of the dash and instrument panel. The low cowl also enhances forward visibility.
Instrumentation and Controls
In designing the instrument panel, the approach was one of simplicity. Since the primary function of the instruments is to relay information as clearly and quickly as possible, the designers opted for a traditional analog execution. The instrument faces are round with white numerals on a black background. The instrument panel is dominated by the tachometer on the left and the speedometer on the right. To the left of the tach are the smaller water temperature and oil pressure gauges. To the right of the speedometer are the fuel gauge and voltmeter. All the major controls are clustered around the steering wheel column to make them easy to reach.
NSX/ NSX-T Interior
The windshield header of the NSX has a special aerodynamic design that directs the airstream up and over the passenger compartment to minimize wind buffeting at speed. It's also equipped with smaller sun visors to enhance visibility.
Additional features unique to the NSX-T include a dash light alerting the driver in the event the roof panel isn't fully latched and a locking mechanism for the roof panel storage compartment.
Dual Air Bag Supplemental Restraint System (SRS) with Automatic Seat Belt Tensioners
The NSX is equipped with drivers and passengers Supplemental Restraint System (SRS) air bags which are intended to supplement the seat belts. In conjunction with these, the NSX features automatic seat belt tensioners which use the same impact sensors as the air bags. The belt tensioners are activated simultaneously with the air bags, causing each belt to retract to help restrain the occupants in the event of a severe frontal collision.
Leather was a natural choice for the seat trim material; it is hand-stitched and handfitted to ensure quality craftsmanship and durability. The seat facings, door inserts, steering wheel and shift knob are covered with leather. The choice of a black or a tan leather-trimmed interior is available for all models, regardless of exterior color.
Automatic Climate Control System
A compact Climate Control System has been developed specifically for the NSX. This is a fully automatic system, but the automatic function can be overridden and the system can be used in a fully manual mode.
Acura/ Bose® Music System
Bose® engineers became involved with the NSX sound system at an early stage of interior design. This 4-speaker system was designed and calibrated specifically for the unique acoustics and resonances of the NSX interior and provides the highest quality imaging and spatial dynamics for both the driver and the passenger.
The Acura/Bose®Music System speakers are precisely aimed so that the pressure wave of the speaker closest to each occupant does not overpower the pressure wave from the speaker which is farthest away. This produces a balanced sound from each speaker and the net result is true stereo performance.
The AM/FM stereo/cassette features Dolby® Noise Reduction and an FM diversity antenna system. The auto preset function will automatically lock on eight strong AM and eight strong FM stations and store them into the preset selector buttons. An optional CD changer is available.
A sophisticated alarm system is standard equipment on the NSX. If an unauthorized attempt is made to enter or start the NSX, the horn sounds, the flashers are activated and the starter system is disabled. The system automatically arms 15 seconds after the doors are locked and is disarmed when a door is unlocked with the key. The system will operate even with the removable roof panel off the car.
The central goal behind the design of the unique NSX assembly plant in Tochigi, Japan, is to produce the highest-quality automotive product in the world.
This plant has no automated conveyor line. Rather, each car is mounted on a dolly and pushed by hand from one workstation to the next. Each team of workers is responsible for the quality of work performed at their station. The car is not passed on to the next area until the team is satisfied that their procedures have achieved the tolerances and goals required in the specifications. Each assembly station, in effect, also functions as an inspection station.
Engine assembly is also done in a unique way to ensure the highest level of assembly quality. Contrary to typical mass production procedures, each NSX engine is assembled by an individual, highly skilled technician from start to finish. This process keeps tolerances to levels that would not be possible in a mass assembly procedure and helps assure reliability and durability.
The NSX is painted in a 23-step paint process, including an aircraft-type chromate coating designed for use with aluminum. A waterborne paint for the base coat was developed to achieve a clearer, more vivid color and a smoother surface finish.
The desired goals for the NSX suspension went well beyond the typical goals of high lateral adhesion, transient response and linear response to control input. The engineers wanted a suspension that allowed the driver to easily control the car right to the limit.
The basic configuration is similar to that of a Formula.One car in that it employs an upper and lower control arm (or double-wishbone) design with a coil-over shock absorber and stabilizer bar front and rear. The rear suspension also has an additional transverse link for greater wheel control. All the suspension arms are made of extremely rigid and durable forged aluminum. The front steering knuckles and the rear hub carriers are also made from heat-treated aluminum castings. The springs are straight rate with an extended rubber bump stop mounted on the chassis which acts as a progressive springing element at the limit of wheel travel.
The shock absorbers are nitrogen-filled and feature a unique progressive valve design. The progressive opening of this valve produces a more favorable damping profile, and more precise damping control, than a conventional valve system in which the fluid control orifices are either fully opened or closed.
The front and rear suspension components are mounted on separate aluminum subframes using rubber bushings, designed to reduce vibration yet limit flex and shift of the suspension components relative to the subframes.
The suspension development program was far-ranging and took place at the Tochigi Proving Grounds, the Suzuka circuit, the 179-turn Nurburgring Coursein Germany, HPCC, and Hondas newest test track in Takasu, Hokkaido. In addition to the standard evaluations conducted in-house by the suspension engineers, the car was subjected to evaluation by top-rank drivers such as the late, three-time Formula One World Cha~pion Ayrton Senna, Indianapolis 500 winner Bobby Rahal, and Formula One dnver Satoru Nakajima.
The NSX is equipped with 4-wheel ventilated disc brakes and dual-piston steel calipers. The diameter of the front and rear discs are 282 mm (11.1in). The braking targets were to set new standards of braking performance and fade resistance, and to provide good pedal feel, linear braking response and low pedal effort. For 1995, new splash guards with cutouts were added to aid in air ventilation and enhance fade resistance.
Four-Channel Anti-Lock Braking System (ABS)
The 4-channel Anti-Lock Braking System controls each wheel independently with a 16-bit microprocessor. This 4-wheel independent capability allows fine control of the anti-lock function especially when the car is braking on a surface with a split coefficient of friction - for instance, if the left side wheels are on snow, ice or standing water and the right side wheels are on dry pavement. The basic configuration is independent parallel hydraulic circuits. In addition to the primary, non-anti-lock braking circuit, the anti-lock system has its own hydraulic reservoir, pump, modulator unit, solenoids and control pistons. If a failure in the anti-lock hydraulic circuit should occur, normal braking force will be fully retained by the primary braking circuit.
Variable Electric Power-Assisted Steering System
This power-assisted steering system was the first of its kind on the American market. The system consists of a rack-and-pinion steering gear with an electric motor installed concentrically around the steering rack. The steering system is a direct design which functions with no assist at higher vehicle speeds. A speed sensor in the electronic control unit determines road speed and, coupled with a steering sensor for torque and rotation, feeds a signal to the motor. To ensure reliability, the electrical system for this unit features gold-plated connectors. Prior to the 1995 model, this system was only available on automatic models. This year all NSX models will feature this electric power-assisted steering system.
Forged Alloy Wheels
To further reduce unsprung weight and provide the highest strength possible, the engineers specified forged-aluminum alloy wheels. The result is a very light wheel with the strength and impact resistance of a much heavier steel wheel. The rear wheels are 8.5 x 17 inches, and the front wheels are 7 x 16 inches.
The suspension engineers, working in conjunction with Yokohama Tire Company and Bridgestone Tire Company, sought to produce tires that would not only provide excellent traction and handling, but also allow the driver to "feel" the limits of the tires' performance.
The resulting uniquely designed tires were remarkable, meeting all the high performance targets the engineers established early in the program.
In 1994, the NSX was equipped with larger, lower aspect ratio tires, front and rear, for more responsive handling and increased cornering capability.The tire sizes are 215/45 ZR16 front and 245/40 ZR17 rear. These tires provide excellent wet- and dry-weather traction, high-speed stability and immediate and predictable reaction to steering input.