I have both the 3800 combo, and the 2400 combo. I have been keeping track of the results for similar speeds in my Stampede 4x4 running Trencher tires. . Thought some here might like to see the info. I started with some rotor pics. Please forgive the Tacon motor, but have it for testing purposes
Rotors of all 3. Note I have already had the 2200 Castle rotor, and the Tacon, side by side, and they are the same size.
Tacon and Castle, with a TRX connector for reference. The Castle rotor is probably about 1.5mm narrower.
3800 installed

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I relocated the esc to the front for better air flow. With the Sidewinder down in the chassis, I was getting much higher temps.
2400
Ran 43.3 mph gpsed with the 13/54 gearing, on 3s. 15 minutes, temps were motor 111, esc 90, ambient 54
I can not gear the 3800 for this speed on 3s with my setup. I sure wish there was a 1412 3000kv motor
Will have to continue.