NASCAR is going restrictor plate racing at Indianapolis Motor Speedway
Teams competing in the NASCAR XFINITY Series race at Indianapolis Motor Speedway later this year will do so with a race package that incorporates three major modifications aimed at one goal — improved competition at the legendary 2.5-mile speedway.
Designed specifically for the 100-lap race scheduled for July 22, the modifications consist of a taller rear spoiler and splitter package; aero ducts on the lower front bumper area; and a 7/8th-inch restrictor plate currently used for superspeedway events at Daytona International Speedway and Talladega Superspeedway.
The static ride height of the cars will remain at 4 inches, which is unchanged from the current 2017 rules package.
The Indianapolis Motor Speedway restrictor plate package was crafted after much in-house simulation and development and then field-tested on Oct. 12 at IMS for verification. 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 NASCAR.com. “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.”
The XFINITY Series has competed at IMS since 2012, and the lack of passing on the big, flat track has been a concern for NASCAR and speedway officials. Kyle Busch (Joe Gibbs Racing) led more than half the laps in winning the last two XFINITY Series races at Indy and he led 92 of 100 when he won the race in 2013.
Dale Earnhardt Jr. addressed the Indianapolis Motor Speedway restrictor plate package this week during his weekly Dale Jr. Download podcast. Earnhardt Jr. competes in the Monster Energy NASCAR Cup Series for Hendrick Motorsports. He is also co-owner of JR Motorsports, which fields four full-time teams in the XFINITY Series.
“I’m curious to see (the changes),” he said. “I think NASCAR sees this as an idea on how fix racing in general at Indianapolis.”
According to NASCAR officials, there currently are no plans in place to utilize the package at any other venue or in the Monster Energy NASCAR Cup Series.
The Indianapolis Motor Speedway restrictor plate race will take place on July 22, 2017.