Honda NSX GT3: Tech analysis

The last of the Japanese ‘Big Three’ to jump into GT3, Honda finally committed to the global sportscar platform to help maintain a presence in IMSA racing on release of the latest GT3 regulation back in 2016. This coincided with the all-new hybrid NSX flagship car back in 2017 – the next generation of the model after a 15-year run by the original car, which was famously tested in development by the late great Ayrton Senna.

MORE TECH ANALYSES | HONDA NSX GT3 ON THE NORDSCHLEIFE

The Honda NSX GT3’s gestation is an interesting one; in that it features a truly global input from three of Honda’s primary motorsport arms across the world. The pen-on-paper design of the car was done by Honda R&D in Japan, using support and knowledge from long-time Honda WTCC factory partner JAS Motorsport in Italy. The car’s base chassis and 3.5-litre twin turbo V6 powerplant is built in Ohio, USA by Honda Performance Development (HPD) – which is also the lead entity that tested and developed the prototype NSX GT3 prior to locking in its FIA homologation. Final assembly and build is done in Italy by JAS Motorsport.

Honda took its first season of IMSA racing as a test bed against some very established manufacturers in the GT3 space. After just one season of racing, Honda released an Evo (upgrade) version of the car – a year or two earlier than most GT3 upgrade kits are released. This kit furthered the car’s overall performance through aerodynamic and drivability tweaks and the spec will remain in place for several years.

Body

With the NSX as Honda’s performance flagship, the car is built for total performance. Long gone are the Japanese manufacturer’s agreement to build performance cars up to a certain level of power – the NSX is kitted out to compete on a supercar level.

At the heart of the NSX is a hybrid chassis – primarily aluminium with key members done in steel. To give the chassis racing-grade stiffness, an FIA compliant chromoly roll-cage is tungsten inert gas (TIG) welded in to handle the dynamic stresses of racing and also to help increase crash repairability. An access hatch is fitted to the roof for driver helmet removal in the case of a heavy crash.

Body work is done in full carbon fibre – similar to other latest GT3 builds. The car’s stance is widened to suit its racing tyres – to 2040mm. Much of the NSX road car shape is retained, with vents repurposed for racing applications. Once the racing build is complete the NSX GT3 weighs 1240kg.

The LED-based headlight arrangement remains from the road car. Supplementary LED racing lights can be fitted to the outer parts of the front vents and are integrated with the bodywork for clean lines. Rear lighting is also cleanly executed and retains the road car profile. A rain light is added to the rear for compliance with GT3 regulation.

Rolling, bumping and stopping

The NSX GT3 is halted by a Brembo brake system, with ventilated steel rotors paired to six-piston front calipers and four-pot rear calipers. These are paired to a Bosch M5 ABS system – a very common GT3 system.

Suspension is provided by double wishbones up front, and multilink system in the rear. Damping is served by five-way adjustable Sachs racing dampers. Mounting points are stiffened courtesy of the roll cage to ensure optimal compliance and sharp handling.

Being mid-engine, rear wheel driven – the NSX GT3 follows the trend of having larger rear rubber than those mounted up front. The front wheels are 315/680 – 18, mounted on 12×18 inch OZ wheel rims, while the rear is 325/705 – 18, on 13×18 inch rims.

Power and Transmission

With the NSX GT3 being fully compliant with the technical regulations, the hybrid system is removed from the car. The sole source of motivation for the car is a mid-mounted longitudinal 3.5-litre 75 degrees V6 twin turbo based off the J35 engine platform – but known as JNC, which does not come with Vtec and is DOHC – placed behind the driver. While heavily related to the famous J35-based HR35TT that powers the Scuderia Glickenhaus SCG003c racer and various prototype sportscars, the NSX GT3 engine is not the same unit. The J35 JNC can produce 500hp in road trim, and after some love from HPD it becomes a 3501cc, 550+hp unit capable of 15,000km before replacement.

Engine management is via a Cosworth ECU, with 12-level Traction Control.

Putting this power to the rear wheels only is an X-Trac sourced six-speed sequential gearbox, sitting directly behind the engine. It connects to the motor via a Sachs clutch system.

The exhaust system for the engine is rearward discharge, from a space above the rear diffuser via twin exhaust systems, each serving one half of the cylinder bank.

Cooling for the motor is done up the front of the car: an angularly mounted unit served by the main grille on the nose of the car and heated air through the coil is exhausted via a bonnet tunnel to a large vent just before the windshield. Intercooling for the turbos is done in the engine bay and fed air by the large intakes on either side of the car just behind the cockpit doors. Air to the engine is also fed from these side vents.

Aerodynamics

The sleek shape of the NSX GT3 makes it fit easily into the field – being comparable in size and shape to the Audi R8, Lamborghini Huracán and McLaren 720S. The low-slung roof line allows for less drag.

At the front of the car, the NSX road car’s three-section front grille arrangement is retained, with the two outer grilles serving air to the front brake assemblies. The central grille, composed of two intakes, feeds air to the main radiator in the bonnet. The car has a pronounced front splitter – updated in the Evo kit to produce more downforce which separates lower speed air over the top and funnels faster flow stream under the car for stronger vacuum. Complimenting this are singular dive planes front corners of the car, mounted quite low – a change on the Evo model. The original car had pairs of dive planes.

The widened body of the car allows for significant work to be done around the wheel arches, with louvres above the wheels to help remove wash from the rotating tyres complimented by a rear facing vent just behind the tyres to provide further assistance and send air flow down the flanks of the car.

The car doesn’t have any pronounced side skirts to separate flow from the sides of the car to the under floor – it is assumed the existing items do enough to prevent interruption to the flow to the diffuser system on the flat floored car, and much of the air flows into the engine bay courtesy of large vertical ‘V’ intakes either side of the car. The upper part of the intake feeds air into the engine, the middle feeds intercoolers and the lower feed air to the rear brake ducts.

Following the roof line of the car, the low-slung NSX has few ducts taking flow from the top of the car – however the engine bay is covered by a slotted louvre panel to help dissipate heat into the atmosphere.

The rear of the car is dominated by the high-mounted rear wing, which sits in clear air outside of the flow over the car. Interestingly, it does not appear to be full width of the car – uncommon in GT3 builds – and is an indication that the car produces reasonable rear downforce levels, and that the reduced width minimises overall drag for more efficiency down the straights. It is mounted via a S bend neck struts to the underside of the wing, which is a straight chord with relatively small endplates.

The rear diffuser is quite sizable for the car – with seven wider tunnels provided on the Evo model after a profile change from the release version. The height of the diffuser is quite tall and the transition from the flat floor starts from just between the rear wheels. Width wise, the out tunnels fan out from the centre of the car to give it a wider final appearance.

Wash from the rear wheels is removed from the car via a set of open ducts located just underneath the rear taillights on either side of the car.

Interior

The NSX GT3 features a stripped-out interior for minimal weight and optimal functionality for racing operations. Within the bare metal and carbon fibre finishes surrounded by the roll cage are the primary equipment for the driver.

An OMP and Honda-designed racing carbon steering wheel is provided, with ten buttons and five dials to operate the car. Light flash, radio, drinks, wipers and the reverse gear are handled by the buttons, as well as start/stop and pit lane speed limiter. Dials control the level of influence on ABS and Traction Control, as well as various pre-tuned engine maps.

The driver is seated in a fixed carbon racing seat by Sparco and held in place by a six-point harness. Pedals and wheel position can be adjusted during a driver swap courtesy of a floating pedal box and adjustable wheel for fore and aft movement. Metrics are provided to the driver via a Bosch DDU10 display.

The FIA racing-grade fuel cell is squeezed behind the driver and forward of the engine, located just aft of the firewall and keeping it out of the cockpit.

Driver comfort in hot conditions is provided via an air conditioning system – optional equipment from the factory but essential for keeping the internal temps to the mandated 40 degrees Celsius during hot races.

Future

The Honda NSX GT3 is a fairly young car compared to many other offerings on the market.

While almost a decade behind some of the more established competition in GT3 racing, Honda’s arrival comes at an interesting time in the formula, with market dominance from the German brands making it difficult to get established, particularly with customer racing programs.

Long-time rival Nissan has retracted its global involvement in GT3 racing significantly since winning the 2015 Blancpain GT Endurance championship and failing in a bid to race competitively at Le Mans, and Toyota’s Lexus RC F GT3 had a twice-aborted entry into the formula that has led to a very radical final build.

Where all three brands still maintain a stronger presence is their domestic market: Japan. Super GT and to a lesser extent Super Taikyu providing consistent order numbers for the cars to race in front of adoring fans of each brand. For 2020 in Super GT, Lexus has four RC F GT3 cars, Nissan five GT-R GT3s and Honda is represented by three NSX GT3s – one notably by long-time brand stalwart ARTA and another by Honda factory favourite Ryo Michigami – this makes up more than half of the 23 GT3 cars in the field.

Both Lexus and Acura remain racing in the American market in IMSA competition – but with the retraction of GT3 factory involvement in that series it remains to be seen how viable the future is for both brands.

Honda has inherited the role of being the leading Japanese representative in GT3 for the Intercontinental GT Challenge in 2020, with the car’s first foray down to Australia to race in the Bathurst 12 Hour. Without significant numbers of cars to bolster the ranks, Honda finds it difficult to lobby for more effective Balance of Performance against the established brands – but increased operations in Europe should help garner more attention.