Actually, back in the 80's, NHRA would let you run a Rotary in Competition Eliminator in D/Econo Dragster and in Super Stock in the Modified Compact classes. Terry Hoard ran an RX-3 that ended up winning a lot of races, and my Dad ran a Rotary in D/ED. The factor on the Rotary engine used to be X2, but when we went out and ran a 9.32 at 131, NHRA decided to start factoring the engine at X2.2 and killed the Rotary engine. Then NHRA came out with the Sport Compact series, and the Rotaries were back, running at a factor of X2.5, and when the Sport Compact series went south, so did the Rotary engine classes. As far as NHRA is concerned, the Rotary can run in the E.T. Bracket classes (Super Pro, Pro, and Sportsman) but only if they can meet the sound requirements, which is normally 98 db at five feet above the ground at sixty feet from the racing surface.Now, if you have ever heard an unmuffled Rotary, you know that they are ear shattering. The dragster we had used to read 132 db at an idle of 3000 rpm, and we used to leave the line and shift at 13,500. No one could seem to get a decibel reading going down the track on the car. Hate that NHRA has factored out the Rotary, because they were a great little engine and a lot of fun to run.