News & Media

Horsepower reduction among 2015 rules package changes

September 23, 2014, Kenny Bruce,

Other tweaks include testing, adjustable track bar

RELATED: Official NASCAR release | Drivers weigh in | Fast facts about new rules package

CONCORD, N.C. -- A reduction in horsepower, a shorter rear spoiler and an optional driver adjustable track bar are among the nearly five dozen changes that encompass the 2015 rules package for NASCAR Sprint Cup Series teams.

After nearly a year of testing and collaboration to arrive at the package, NASCAR officials informed teams of the 2015 changes this week.

In addition to the changes in "hard parts," NASCAR has banned all private testing by teams for next season. Organizations will be allowed to participate in NASCAR/Goodyear tests only.


Teams currently are allowed to test at non-sanctioned facilities as often as they choose, and have a minimum number of tests allowed at tracks that host Sprint Cup Series races.

There also will not be a preseason test at Daytona International Speedway leading into the season-opening Daytona 500. Teams were expected to be at the 2.5-mile track in January for the annual Preseason Thunder program.

There could also be qualifying and racing in the rain at Sprint Cup Series events contested on road courses if weather is an issue; and the new qualifying format unveiled this year could see some minor tweaks going forward.

"Last year when we did the chassis change, we wanted to do the engine power optimization, but it was too much, too fast for the engine builders," Gene Stefanyshyn told

Stefanyshyn, senior vice president of innovation and racing development, said speeds increased slightly with the implementation of the 2014 package, "so this year, even though we've got the power down, we're re-balancing the car."

The horsepower reduction, from 850 to 725, will be obtained in part through the use of tapered spacers, which are currently used in the NASCAR Nationwide Series and NASCAR Camping World Truck Series.

Flat valve lifters will be replaced with roller valve lifters; lower differential gear ratios (targeting 9,000 RPM) will be in use and the rear spoiler height will be reduced from 8 inches to 6 inches.

An adjustable driver track bar will be optional (the device was tested this summer at Michigan International Speedway); while the size of the radiator pan has been decreased from 43 inches to 38 inches.

Stefanyshyn said speeds will likely decrease by no more than 3-4 mph in most instances with the changes.

"You take the power out, but we're also taking drag off (by trimming the spoiler) to re-balance this whole thing," he said. "It's not going to be as dramatic as most people think. We're hoping … it will make the racing better, closer. Our goals are always that, right? To provide better entertainment for our fans."

The move to eliminate testing, he said, was at the request of teams. Any team that is caught skirting the rule will face a P6 penalty, the most severe.

"They say 'it cost a ton of money, takes a ton of time, a ton of resources,' " Stefanyshyn said. "They say, 'We test at tracks we don't race at, they're not rubbered in. When all is said and done, what is whole value of thing?'

"They all say that, but they all go (test) because the other guy is going. So how can we control all you guys, where you go? They said, 'Hey, put down a severe penalty.' So it’s a P6. It's a big one.

"We won't put a bodyguard with each team and follow them around but … thinking that people will let you know (if anyone breaks the rule)."

Teams will still test, but those tests will likely be run in conjunction with Goodyear tire tests and NASCAR.

"What we're trying to do is get Goodyear, NASCAR and team testing, which are separate now, and bring all three of us together," he said. "If we organize it well and do it in a smart way, say 'Goodyear's got to do their stuff, let's help them; NASCAR and the teams, if we want to look at this low downforce world, let's work together; and then you teams, you've got your time.'

"That's the thinking but we have to figure all that out."

Previously announced for 2015 were the move to automated pit road officiating, a new parts approval process and the implementation of an electronic rule book.