Acura Reveals ARX-06 LMDh Design, Technical Details

Acura and Honda Performance Development have revealed the design and technical details of the Acura ARX-06 LMDh prototype, including a 2.4-liter twin-turbocharged V6 engine.

The sixth-generation Acura sports prototype, which underwent its first track test last month, will debut in next year’s IMSA WeatherTech SportsCar Championship with single-car entries from Meyer Shank Racing and Wayne Taylor Racing in the GTP class.

Acura Motorsports and HPD will officially unveil the car at The Quail, an event during Monterey Car Week, on Friday.

Wednesday’s announcement included the first images of the car’s design without its camouflage testing livery and also confirmed key details about the technical specs.

The ARX-06’s part-electric powertrain, named the Acura AR24e, consists of the internal combustion engine connected to the spec LMDh hybrid system comprising a Bosch electric motor, Xtrac transmission and Williams Advanced Engineering battery pack.

The car’s direct injection engine, which has been developed by HPD, has a smaller displacement than the 3.5-liter V6 that powers its DPi predecessor, the Acura ARX-05.

At 2.4 liters, the new engine is the smallest displacement power unit produced by HPD for endurance racing to date.

Against the other LMDh brands, it compares with a 4.6-liter twin-turbo V8 from Porsche, a 4.0-liter twin-turbo V8 from BMW and a 5.5-liter V8 from Cadillac.

Acura says that the ARX-06 engine will meet the LMDh power target of 500 kW, which is measured by torque meters at the rear axle, while the combustion chamber has been designed to run on sustainable low-carbon fuel.

The engine is positioned at a 90-degree V-angle to lower its center of gravity and reduce the polar moment of inertia.

HPD has developed hybrid powertrain control, brake-by-wire and vehicle dynamics control systems that are implemented on electronic control unit hardware from Formula 1.

“We’ve taken the challenge presented by this new rule package from IMSA and the ACO, and developed what we believe is a very competitive solution,” said Pierre Descamps, HPD powertrain design team leader for the ARX-06.

“We’ve gone in a new direction for HPD in the design of the ICE. It is still a V6, which of course for Honda is well-known, but we have incorporated several new elements which we believe will make best use of the electric MGU and battery pack.

“Our new engine will rev to the maximum 10,000 RPM set by the rules, so it also makes a wonderful sound!”

The Acura ARX-06 is built on an ORECA chassis, with Acura-specific aerodynamics incorporated into the overall design.

HPD’s Vehicle Performance Group collaborated “closely” with ORECA engineers to simulate different options for how to develop the car.

As alluded to in previous imagery, the ARX-06’s front end resembles that of its ARX-05 forebear, with the nose stooping under a bridge between the front lights.

The car’s exterior styling was carried out by the Los Angeles-based Acura Design Studio, in conjunction with HPD and ORECA’s engineers, to “maximize the aerodynamic performance envelope” while keeping in line with IMSA and FIA homologation criteria.

The ARX-06 is built to the maximum dimensions allowed in the LMDh technical regulations, measuring 5.1 meters long, 2 meters wide and 1.06 meters high with a 3148 mm wheelbase.

“We’re extremely pleased with our relationship with ORECA,” commented Mark Crawford, HPD Large Project Leader for the Acura ARX-06.

“They’ve been great partners throughout both our ARX-05 DPi program and now with the ARX-06.

“The GTP project has brought with it a new set of challenges and, while you certainly can see the Acura ‘family resemblance’ to our previous collaboration, the ARX-06 is an entirely new design.”

Acura’s Executive Creative Director, Dave Marek, added: “The same world-class stylists that lead Acura production car design created initial sketches, then pared those down to several potential designs.

“Next, we created a scale model, did aero and wind tunnel model testing, and brought HPD and our partner teams in for their feedback.

“The design continued to be refined throughout the testing and evaluation process until we came up with a final treatment that met our performance goals while maintaining all-important Acura styling cues.”

According to Acura, input from the program’s affiliated drivers and teams contributed to the ARX-06’s design.

For example, the rearview wing mirrors were lowered following consultation with drivers using virtual reality headsets.

Outlining the car’s development process, HPD President and technical director Dave Salters said: “We started with the rule book, a challenging spirit and an open mind.

“Then our engineers got to work, utilizing all of the vehicle performance, powertrain simulation and development tools we have at HPD to address the critical areas for performance, including weight, power, packaging and center of gravity.

He continued: “We are HPD. We race, we develop our engineers and technology through racing.

“We have an amazing and unique racing legacy, both past and present. It’s what we do as Acura’s — and Honda’s — North American racing organization.

“We are looking forward to the challenge of racing Porsche, BMW and GM in IMSA’s pinnacle GTP championship.

“We are very cognizant this is a big step for us. We have a lot to learn, but that is why race.”