Not to argue a dead topic...but BLE, Barichello's Ferrari red lines at over 20,000rpm. So, yeah...it's a four stroke, but it's revving up higher than most people's two strokes do. Just think of how amazing that precision is. Also, both that car and the "four stroke powered retro rail" have almost unrestricted exhausts giving as much boost in performance as possible. Why do you think Harley's are so much louder than Civics? Exhausts!! They rev up way less, but have those big beefy exhausts. So...I'm just pointing out that rules of thumb apply to the vast majority of things. Also, R/C engines meant for reliability and fun aren't the same as engines costing hundreds of thousands of dollars with millions of dollars invested in designing them for absolute maximum power and minimum endurance. That's why (until recently) F1 had a one engine per race weekend limit on cars. Then they limited it to one engine every two until they made the engines V8's and increased it back to one per weekend. If not, I have no doubt that teams would have an engine each for practice, qualifying, and the race. I've owned one 4-stroke and 6 2-strokes. I crashed my Saito 100...a 280 dollar engine that cost me 160 in parts. It would've been over 200 for shipping the engine to and from HorizonHobby and the labor on it. I also buried a 46AX 8 inches in mud and over 3 feet of water. I pulled it apart and soaked it in WD40 for 3 days (first chance I had to get back to it) put it back together (i mean cylinder head, carburetor, and muffler ONLY) and it still started first flip. Now, I love my Saito to death (still waiting on the parts for it), and it intrigues me that it can turn such a huge prop with so little problem, but my AX has never given me anything but love and support!!