[VintageMA]

I've been reading that a 1506 should be fine to push a CRT.5 and a 1509 may be overkill. Looking to move from a 3S to a 6S setup to reduce amp draw and increase efficiency gearing for a modest 40mph - nothing crazy. Would like to keep the motor RPMs around 30-35K.

A few choices: (assuming quality LiPos holding 3.5v/cell under load - 6*3.5 = 21V)

1506/3Y 1850 = 38850 rpm

1509/2.5Y 1450 = 30450 rpm

So which do you think would run cooler with less amp spikes and overall draw?

The 1506 is a smaller motor and will draw less overall, but with a higher kv it may pull larger spikes trying to spin-up.

The 1509 will have more torque and a more mellow spin-up amp draw, but it's a larger motor and the added torque will come at the expense or more current.

I'm only getting 10 minutes run-time with 3S and a LMT 1930/6. Motor and esc cool, but lipos are touching 130*.