The Rotary has no red line. The only problem it they are junk after so many miles. The apex ring is the only week spot on them. When they fall out there done. Remove the rev limiter and have fun. They were banned in Formula 1 because they could come out of the corner at 12,000 RPM while the other cars needed to run back up. Once they banned them Mazda left the Formula series. That stopped the development of them.