HK 4035 Series 4035-400 4035-500 4035-560 4035-630 Kv (rpm/V) 400 500 560 630 Max Power (W) 3500W 3500W 4200W 4200W Max Amp (15sec) 84A 84A 100A 120A Max Efficiency 85% 85% 85% 85% Io (No load A) 1.38A 1.9A 1.74A 1.74A Rm (Resistance) 0.028Ohm 0.020Ohm 0.012Ohm 0.012Ohm Shaft Diameter 8mm 6mm 6mm 6mm Gearbox N/A N/A N/A N/A Motor Diameter 48.9mm 48.9mm 48.9mm 48.9mm Motor Length 61.5mm 61.5mm 61.5mm 61.5mm Motor Weight 400g 400g 400g 400g Built in Fan Yes Yes Yes Yes Max Rpm 24,000 24,000 24,000 24,000 Poles 10 10 10 10 Case Outrunner Outrunner Outrunner Outrunner ESC Timing 20-25 deg 20-25 deg 20-25 deg 20-25 deg ESC Switching Freq. 8-16KHz 8-16KHz 8-16KHz 8-16KHz