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[h=2]IMSA 2017 Prototype Tech Profile: Mazda RT24-P[/h] Thursday, 26 January 2017


Marshall Pruett (words and images)

ORIGINS AND PERFORMANCE:

Mazda continued its relationship with Canada’s Multimatic and resumed an old partnership with Riley Technologies to produce its Daytona Prototype international. Mazda’s RT24-P (Road to 24-Prototype), the first DPi unveiled to the public, was built upon the WEC P2-spec Riley/Multimatic Mk 30 and represents a significant and inspired departure from that base model.
With IMSA’s mandate for auto manufacturers to make notable styling changes to the bodywork of their respective WEC-based DPis, Mazda mobilized a group from its North American and Japanese design departments to work with Mk 30 aerodynamicist Mark Handford while penning the RT24-P’s aerodynamics.
The result, according to many fans, is a shape that ranks atop the list of beauty and functionality in IMSA’s WeatherTech SportsCar Championship Prototype class. Handford’s utilitarian approach to the Mk 30, with its blunt nose and traditional lines from nose to tail, has been altered in every imaginable way with the RT24-P.
Soft, rounded front fenders are wholly unique among the six P2-based models in the Prototype category, and in almost every area where the Mk 30 has sharp, angular bodywork, the RT24-P sports curves and appealing contours. And as the speed traps revealed during the three-day Roar Before the 24 test, the Mazda’s flowing lines aren’t just for show: The No. 55 RT24-P set the fastest top speed of the event (while the Mk 30 was the slowest in class) and delivered the second-fastest lap of the Roar.
More speed is expected to come from the Cadillac DPis and the WEC Ligier JS P217 in the season-opening race, so the Mazda’s pace will likely have some company toward the top of the field, but as a whole, the performance gap between the RT24-P and the WEC Mk 30 has been remarkable.
Beyond the fundamental aerodynamic differences to the Mk 30, the Mazdas are also powered by something different than the spec Gibson V8 carried in every WEC P2 – a new version of its venerable 2.0-liter four-cylinder turbo engine.
The RT24-P made its public debut on-track during IMSA’s mid-December test at Daytona with a single car using an exhaust outlet in the left-rear portion of the sidepod. Noting the use of periscope-style exhausts on other prototypes at the test, and unaware it was an option, Mazda returned for the Roar with two cars and two exhaust configurations – one in the same sidepod location and the other with a periscope atop the left side of the engine cover.
From the Roar exhaust evaluation and further dyno testing, the simplified periscope layout, which features fewer power-robbing twists and bends than the sidepod-exiting configuration, freed more grunt from the engine. A slight decrease in radiator temperatures due to the exhaust being directed to the rear was also found. The periscope, as one would expect, has been chosen for both cars starting at the Rolex 24.
As noted with the Mk 30, one development issue – gearbox cooling – plagued the RT24-Ps in testing, but those issues were reported to be resolved before the end of the Roar. High ambient heat is still a cause for concern when it comes to gearbox cooling, and the SpeedSource-led Mazda team has options to move some of its cooling options in the sidepod and engine cover to direct more or less air to the gearbox cooler.
Inside and out, the RT24-P has the potential to make Mazda a serious player in 2017 and for many years to come. The development race against Cadillac (and Nissan at some point) will ensure the DPis are a source of intrigue and drama, and with reliability issues expected to plague every prototype model at the Rolex 24, it’s impossible to predict which brand will land in Victory Lane. As the only model without Cosworth electronics on board, the RT24-P should have fewer concerns about software or hardware failures than its competition.