After joining forces with Team Mugen during the off-season, ARTA has expanded to two Bridgestone-shod Honda NSX-GTs for the 2023 season as it bids for a first GT500 title since 2007.
The team has frequently topped the timesheets during the winter, with Nojiri's new team-mate Toshiki Oyu notably setting a new unofficial lap record in a private test at Suzuka earlier in the month in the #8 car.
That trend continued in the first official test at Okayama, where it was the sister #16 machine of Nirei Fukuzumi that set the quickest time across the two days.
The #8 car of Nojiri and Oyu was fourth-fastest, but was second during a qualifying simulation on the afternoon of the first day behind the #16 car that Fukuzumi shares with Hiroki Otsu.
However, Fukuzumi expressed some concerns about ARTA's long-run pace, something that Nojiri echoed when asked to assess the team's performance.
Nojiri said that trying to use the strong points of the #16 car to boost the #8 car hasn't been working as well as the team hoped.
"Whether we’re doing well or not, we are unfortunately understanding a lot of things with two cars," he told Motorsport.com's Japanese edition.
"This is something everyone in SUPER GT feels, but even though we have a standard chassis, the difference between individual chassis is so big now that it’s hard to put it down to just production errors.
"The difference between the cars is so great that we can’t use each other’s data. For that reason, we can’t fully get rid of the things we don’t like about each car. We have different troubles with cars #8 and #16."
Nojiri admitted he was puzzled that ARTA was able to lead the timesheets on Saturday afternoon considering its problems, which have left him concerned about the team's performances in warm weather.
He explained: "The thing that’s wrong with the #8 car is a lack of stiffness at the front. We tried increasing the stiffness, but when the conditions change and it gets warmer with less downforce, we can’t run that stiff.
"Now we’re wondering what to do. It feels like with our current set-up, we are going to have the same issues as we faced last year in hot races."
Nojiri stressed that a strong result in the Okayama opener, which is likely to be among the cooler races of the season, is less important than the Mugen-run ARTA squad increasing its understanding of its problems.
"I want to get off to a good start, but the most important is with every passing race that we get stronger as a team," said Nojiri. "I want to solve our problems in the first half of the season.
"While I hope we can make a good start, I hope we can also pay those problems enough attention."
