Stephen Simpson in LMP2 ahead of Cadillac DPi cars during Watkins Glen six hours
A flawless final stint by Stephen Simpson in JDC-Miller Motorsports' No. 99 ORECA 07 ensured an LMP2 car won overall at the 2018 Sahlen's Six Hours of The Glen. | Photo: Jake Galstad / IMSA

In a notable shift from the first five rounds of the 2018 IMSA WeatherTech SportsCar Championship season, the series’ July 1 visit to Watkins Glen International saw LMP2 prototypes outshine their Daytona Prototype international competition over the course of the six-hour endurance race.

Having earned the pole on outright pace, CORE autosport proved with its ORECA 07 that the Gibson-powered LMP2 cars could hold their own against the Acura, Cadillac, Mazda and Nissan DPi cars. And after six hours of racing a day later in upstate New York, three LMP2 cars were scored in the top five and — remarkably, given the first five rounds of the season — two ORECA 07s finished first and second, relegating the top DPi car to a third-place finish.

At the season-opening Rolex 24 at Daytona, attrition struck much of the DPi field allowing three international-spec prototypes to finish in the top five. Yet, the two Cadillac DPi-V.Rs of Action Express Racing finished the 24-hour contest in first and second, reestablishing a trend of DPi dominance that persevered through the first six months of 2018, the second year of the “DPi” era that opened at Daytona a year earlier.

Acura DPi chased by LMP2 during six hours of Watkins Glen
With its ARX-05, Acura joined the Prototype battle for 2018 to compete against Cadillac, Mazda, Nissan and LMP2 machinery. | Photo: Jake Galstad / IMSA

The year’s second race at Sebring International Raceway once again swung the way of the DPis with the Nissan Onroak DPi of Tequila Patron ESM taking the overall victory ahead of two Cadillac DPis on the podium. CORE and United Autosports complete the top five with their LMP2 machinery.

The streets of Long Beach in April represented the first sprint race of the season and the 100-minute run to the checkers provided even more evidence for those tracking the impossible plight of LMP2 cars in the face of DPi superiority. Cadillac, Nissan, Mazda and Acura DPis locked out the top seven positions with one of JDC-Miller Motorsports’ ORECA 07s the top non-DPi prototype in eighth.

Rather than offering a glimpse of equilibrium between LMP2 and DPi cars, the season’s first two-hour, 40-minute race only demonstrated the ascendancy of the Acura ARX-05 and Mazda’s continued progress after being taken over by Team Joest. The Acura Sports Car Challenge at the Mid-Ohio Sports Car Course ended with two Acuras and a Mazda in the top three and Cadillacs filling out the rest of the top five. The race’s top LMP2 car, the Ligier JS P217of AFS/PR1 Mathiasen Motorsports, was joined by only one other non-DPi prototype in the top 10.

After debuting at Mid-Ohio, the modern DPi and LMP2 cars made the trip to Detroit’s Belle Isle where the custom suspension components of the DPi manufacturers lent those cars an advantage, as was demonstrated in Southern California. Only AFS/PR1 Mathiason’s Ligier and JDC-Miller’s ORECA made it into the top 10 in Detroit, split by a Mazda RT24-P.

Considering the track record of DPi versus LMP2 competition, this year’s Sahlen’s Six Hours of The Glen stands in stark contrast to the five races that preceded it.

Unlike at Daytona, where failing DPis led to modest success for LMP2 cars, speed proved to be the great equalizer at Watkins Glen. Of the 10 fastest race laps, six were set by those piloting LMP2 cars, led by CORE’s Romain Dumas. Dumas’ best time, a 1:33.619, was just under two-tenths of a second shy of Ricky Taylor’s chart-topping lap in his Acura DPi.

CORE autosport ORECA LMP2 through Daytona chicane during Rolex 24
In their Prototype debut, CORE autosport was the top LMP2 team after 24 hours of racing at Daytona in January 2018. | Photo: Scott R LePage / IMSA

Broken down by sector, LMP2 cars were strongest in the first sector which stretches from the start-finish line to the backstraight before the inner loop. Here, LMP2 cars had the four fastest times with Paul Di Resta quickest in United Autosports’ Ligier. While DPis were strong in Sector 2, which includes Turn 5’s inner and outer loops through the toe of the boot at Turn 7, CORE’s ORECA was second fastest. The ORECA, however, was quickest in Sector 3, which runs from Turn 8 through to the end of the lap.

From an “ideal lap” standpoint, which combines each car’s best sector into a perfect lap, CORE’s ORECA had the most potential for fast laps based on sector performance. The 10 fastest ideal laps were split evenly between LMP2 and DPi cars, demonstrating that sought-after parity might have been reached in the Prototype division at the smooth 3.4-mile Watkins Glen circuit.

Six races into the season, the mixed prototype class employed by IMSA seems to have achieved its promise. However, year-to-date data strongly points to a DPi advantage in non-endurance rounds. With the next three races for Prototype set to return to the standard 160-minute duration, the push and pull of manufacturer-supported DPi cars against spec LMP2 machinery will remain in the spotlight.

The next chance to acquire evidence of true prototype parity will come July 8 at Canadian Tire Motorsport Park with the Mobil 1 Sports Car Grand Prix.

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