NASCAR to use restrictor plates as part of new package for Xfinity race at Indy

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NASCAR announced Thursday that a new package will be used for the July 22 NASCAR Xfinity Series race at Indianapolis Motor Speedway.

The new package is meant to increase competition in the 100-lap race on the 2.5-mile speedway. Last year’s race was the subject of criticism due to the lack of passing. Kyle Busch led 62 of the 63 laps and there were only two passes.

The package consists of a taller rear spoiler and splitter package along with aero ducts on the lower front bumper area. There will also be a 7/8th-inch restrictor plate currently used for superspeedway events at Daytona International Speedway and Talladega Superspeedway.

NASCAR said the Indy package was developed after a great deal in-house simulation and development and then field-tested last October at IMS. Xfinity Series teams from Richard Childress Racing, Roush Fenway Racing and Kaulig Racing participated in the test.

“We (develop) the analytical package and come to some conclusions,” Gene Stefanyshyn, NASCAR Senior Vice President, Innovation and Racing Development, told “But then we also need to go on the track and verify this. So this approach has been a two-step approach, analytical creation of the package and then on-track verification.

“We race at 29 tracks (across all three-national series) and they’re all very special,” Stefanyshyn added. “Indianapolis has a long history; it’s a wonderful track. Our objective is to give our fans the best possible show we can. We are very proud of being able to participate at Indy; we want to put our best foot forward. We believe we have come up with a package that gives us the best opportunity to do that.”

Stefanyshyn said officials had teams run various packages during the test. While the use of the restrictor plates enabled the cars to run closer together, the ability to pull out and pass remained difficult.

“We saw the cars were closer together, but we weren’t able to create some passing until we introduced the aero ducts,” he said. “That’s the main purpose of the ducts, to give the trailing car more of an advantage … we always hear about clean air and how the leader has clean air. Our objective here is to try to give the trail car more benefit.”

Without the aero ducts, cars running down long straightaways such as those at IMS hit a wall of air, which creates “a significant horsepower deficit” when they get within approximately one car-length of the lead car, Stefanyshyn said.

The aero ducts direct air in through the existing brake ducts and out through the wheelhouse on each side. The high-speed air flowing out creates a larger hole or “envelope” for the trailing car.

Use of the aero ducts should increase the amount of horsepower differential for the trailing car by approximately 25 percent.

“We’re giving the driver more momentum from four-five car lengths back, gaining coming into within half a car length; when he gets right into that bubble, he’s still got to cross through it, but he’s carrying momentum and he can break through it,” Stefanyshyn said.

Stefanyshyn said incorporation of the package isn’t “a slam dunk,” but studies and testing have thus far validated the changes.

“Our belief is that we will create a situation where they can pass on the straightaways,” he said. “That’s been done analytically, it’s been done with three cars. The question is when we turn 40 cars loose on the track can that still manifest itself and that’s still what we’re hoping will happen.”

Speeds likely won’t vary greatly with the new package, and the use of restrictor plates isn’t expected to generate the big packs of traffic on the track similar to what typically is seen at Daytona and Talladega. Stefanyshyn said it’s more likely that there will be several groups of five or six cars each, “and in each of those groupings we’re hoping to see passing on the straightaways.”

Greg Engle
About Greg Engle 7421 Articles
Greg is a published award winning sportswriter who spent 23 years combined active and active reserve military service, much of that in and around the Special Operations community. Greg is the author of "The Nuts and Bolts of NASCAR: The Definitive Viewers' Guide to Big-Time Stock Car Auto Racing" and has been published in major publications across the country including the Los Angeles Times, the Cleveland Plain Dealer and the Atlanta Journal-Constitution. He was also a contributor to Chicken Soup for the NASCAR Soul, published in 2010, and the Christmas edition in 2016. He wrote as the NASCAR, Formula 1, Auto Reviews and National Veterans Affairs Examiner for and has appeared on Fox News. He holds a BS degree in communications, a Masters degree in psychology and is currently a PhD candidate majoring in psychology. He is currently the weekend Motorsports Editor for Autoweek.