Former Daytona 500 winner Jamie McMurray may have recorded the fastest prototype lap of the day in Roar before the 24 testing today, but the Ford-powered Ganassi squad were forced to leave the test early.

Exhaust header failures on the new Ford EcoBoost turbo machines resulted in both the two Ganassi and the Michael Shank Racing entry packing up with one day of the test remaining.

Prior to the issue, McMurray set the fastest time of the day at 1:38.980

“Today we’re really trying to get the car comfortable for everyone,” McMurray said.

“The car is different from the one we raced here last year, with traction control, and it drives differently with the turbocharger. Absolutely, this would be a huge race to win. I’ve won the Daytona 500 and the Coke Zero 400, and even won in go-karts here. It would be awesome to win the Rolex 24.”

McMurray shares the No.1 car with defending Rolex 24 winners Scott Pruett and Memo Rojas and reigning Indy Lights champion Sage Karam. The team is looking to give Chip Ganassi Racing with Felix Sabates its sixth Rolex 24 victory since 2006.

Teams battled cool temperatures throughout the day in Daytona – completing four sessions including a night practice which was topped by Christian Fittipaldi in the Action Express entry. The Brazilian set a fastest time of 1:39.223 ahead of Ricky Taylor’s Daytona Prototype and David Brabham aboard ESM’s P2 HPD car.

Brabham originally ushered in the Daytona Prototype era in the Rolex 24 by winning the class in 2003, driving for Multimatic Motorsports. This year he teams up with Scott Sharp and Ryan Dalziel for Extreme Speed.

“It’s kind of cool to be racing in the first TUDOR Championship race, after being involved here in the very beginning of the DPs here,” Brabham said.

“The DPs have come a long way since then. Obviously, I’m used to the P2, having raced the HPD since 2007 and I know the car very well. It’s difficult to say what’s going to happen in the Rolex 24. The two cars have strengths in different areas and perform quite the opposite. It will be a fascinating battle as it goes on.”