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Inside Acura: Birth of a DPi Car

Inside the conception, development and early success of Acura’s ARX-05 DPi car…

Photo: Rick Dole/IMSA

While Acura may be the newest DPi manufacturer on the IMSA WeatherTech SportsCar Championship grid, having made its debut in this year’s Rolex 24 at Daytona, preparations for its entry into top-level IMSA prototype competition had been in the works for quite some time.

In fact, work began the moment the FIA, ACO and IMSA formalized the LMP2 regulations, which DPi would be based from, back in early 2016. 

At that time, Honda Performance Development was off to a winning start in the WeatherTech Championship, with victories in both the Rolex 24 at Daytona and Mobil 1 Twelve Hours of Sebring with Tequila Patron ESM’s Honda-powered Ligier JS P2, while the Acura NSX GT3, set for a 2017 race debut, was announced in March. 

It led to a busy time for Honda’s California-based motorsports department, according to HPD Race Team Leader Allen Miller.

“When DPi was coming, we had already set our direction to do the NSX GT3, so we didn’t go full-bore but we definitely started researching and talking with constructors,” Miller told Sportscar365.

“Throughout 2016 we started interviewing and looking at the products they’d have.”

With a 2017 debut, the first year of IMSA’s new LMP2-based formula, having been ruled out from the onset, HPD instead worked to secure the necessary partners for its first factory prototype operation since Acura’s championship-winning American Le Mans Series effort in 2007-09.

Photo: Mike Levitt/IMSA

Miller (pictured above, left), along with Acura DPi program manager Matt Niles, who were both part of the previous ALMS program, made visits to all four LMP2 constructors throughout 2016 before partnering with ORECA late in the year.

It came at a time when the Oreca 07, which the Acura ARX-05 would be based from, hadn’t even yet made its race debut.

By early 2017, HPD finalized its other major partnership in Team Penske, which as the year unfolded, turned into one of the worst-kept secrets in the media prior to its official confirmation in July.

The legendary motorsports organization, which last worked with Honda in 2011, played a crucial role in the program’s early development, according to Niles.

“Starting pretty early in 2017, we were having weekly calls with all three of us to sort through crunch lists on what to do,” he said.

“Because we had one team, it was easy to involve them and work together. We all brought our own resources and expertise to the table, so we were able to pick and choose what was the best way.

“Whether it was headlights or air conditioning mounting, there were a lot of changes compared to the LMP2 car.”

One of the biggest changes came with the car’s appearance, thanks to IMSA’s DPi-specific styling allowances that allowed HPD to work hand-in-hand with Acura’s design team to create an Acura-inspired design for the ARX-05.

Photo: Acura

“We went down to the design studio in Los Angeles, sat down with their designers,” Niles said. “We pulled up the rule book and said, ‘Here are the things that are open.’ They’ve worked with us in the past and they know racing and that there are limits.

“Out of that, they went through and tried a bunch of things and narrowed in on this. We gave feedback on it technically.”

While early CFD studies on the aero proved successful, Niles and Miller said the biggest challenge was achieving sufficient cooling to the twin-turbocharged AR35TT engine.

The 3.5-liter powerplant, derived from the Acura MDX, had already proven its success in the previous-generation Ligier LMP2 chassis, as well as in 2.8-liter form in the 24 Hours of Le Mans LMP2 class-winning HPD ARX-03b, although it was the first time in an Oreca, which was designed for the LMP2 class-spec normally aspirated Gibson engine.

Miller admitted IMSA’s DPi homologation process was also very thorough, although HPD’s previous experience in working with the sanctioning body made it relatively seamless. 

“With LMP2, with the homologation, it was, ‘Here’s our engine, here’s our car.’ It was like a ten-page document. Now it’s very detailed and very specific,” Miller said.

Niles added: “We were obviously running LMP2 cars against the DPs in 2015 and 2016 and we got that relationship with IMSA. We were part of the process, such as the dyno testing, and observed some of the wind tunnel testing.

“And going through the process with the GT3 car beforehand, it actually helped us through that process, from our side. It helped make it smoother with the DPi car.”

Photo: Acura

Despite some challenges, as with any new car, HPD and ORECA hit their major target of getting the Acura DPi on track by July 2017.

Juan Pablo Montoya handled driving duties at the first rollout at Paul Ricard, which was followed up by its first test in the U.S. at Road Atlanta in August.

“We set that target really early on in the project, so that was really good to hit that,” Niles said. “We pushed really hard to get on track as soon as we could.”

Less than one year later, and just four races into its first season, Acura Team Penske’s Ricky Taylor and Helio Castroneves delivered the ARX-05’s maiden victory at Mid-Ohio, in a dominant sweep of the weekend for the manufacturer.

According to Niles, it validated the nearly two years of work that had been put into program, in the birth of Acura’s DPi car.

“It was good to just check that box off,” he said. “Helio nearly got the pole at Daytona and just getting the pole at Long Beach was good. We learned a lot about the car there. After then, we just doubled down and made sure it was all good at Mid-Ohio.”

With multiple returns to the podium, the first-year program concluded with Acura finishing runner-up in the Prototype manufacturers’ championship and Montoya and Dane Cameron the best-placed Team Penske driver pairing in fifth, in what proved to be a hotly contested season.

Photo: Mike Levitt/IMSA

John Dagys is the founder and Editor-in-Chief of Sportscar365. Dagys spent eight years as a motorsports correspondent for and SPEED Channel and has contributed to numerous other motorsports publications worldwide. Contact John

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