Lee White, senior vice president for Toyota Racing Development, said Wednesday that the changes are part of Toyota’s efforts at “continual development and improvement of the product we have.”

White said results of chassis dynamometer tests following the Cup race at Atlanta earlier this year showed that Toyota has as much top-end horsepower as any other manufacturer’s engine. But at lower RPMs - when cars are trying to get off the turns and back up to full speed for straightaways - the Toyotas were not making as much power as other cars.

“We’ve been working a lot of hours, seven days a week, trying to make the power curve look more like that of the people who’re beating us,” White said.

The improvements include changes to existing parts and did not require NASCAR approval.

“There was no going to NASCAR and saying, ‘Can you give us this or help us out,’” White said.  ThatsRacin.com