The IMSA Continental Tire SportsCar Challenge will adopt GT4 regulations, beginning next year for its GS class, as part of a shakeup to the series, which features revised race lengths for 2017.

IMSA revealed a 10-round schedule for next year, with four-hour races planned at Daytona and Mazda Raceway Laguna Seca and a reduction from two-hour and 30-minute races to two-hour races for the remainder of the season.

“We expect that the addition of two endurance races to the IMSA Continental Tire SportsCar Challenge in 2017 will be welcome news for series competitors and fans,” said IMSA President Scott Atherton.

“Next year, we will begin the transition to GT4 technical specifications for the Grand Sport class ahead of full integration in 2018.

“As a result, we anticipate an intriguing and diverse mix of race cars in both the Grand Sport and Street Tuner classes at all 10 races next season.”

The sanctioning body has established a cooperation agreement with SRO Motorsports Group to utilize the GT4 platform, which will be eligible beginning next year and fully integrated into the GS class by 2018.

Existing GS class cars will be grandfathered for next year.

No changes will be made to the ST class through the end of the 2018 season, although IMSA is in dialogue with TCR creator Marcello Lotti regarding a cooperation agreement for the launch of an additional class for the touring cars for as early as 2018.

2017 Continental Tire SportsCar Challenge Schedule:

Jan 27 Daytona International Speedway (4 hours)

Mar 17 Sebring International Raceway

May 6 Circuit of The Americas

Jul 1 Watkins Glen International

Jul 8 Canadian Tire Motorsport Park

Jul 22 Lime Rock Park

Aug 5 Road America

Aug 26 Virginia International Raceway

Sep 23 Mazda Raceway Laguna Seca (4 hours)*

Oct 6 Road Atlanta

*Subject to final confirmation