ok this is of the top of my head but should be 99% correct
when brushless was becoming popular there was suppose to be a rough equivalent by dividing a brushed by 1.8 ? or so.
usally the brushless had a bit lower rpm at same voltage but a lot more torque.
with the "y" there is two winds that are used generally with brushless motors
most of the brushless motors we use in 1/10 on road are Y wind motors
the difference between the two
a Y wind motor will have 1.73 times more torque than a delta wind
the delta wind will have 1.73 times the kv of the y wind.the wye is more efficient than the delta wind
so just say a 13.5 turn Y wind was 3300 kv,the same 13.5 wind in a delta would be around 5700 kv
getting a KV chart for turns is near impossible as each company quote diffrent kv,s for there winds (turns)
but its unknown how each company test there motor kv,s
as its possible to calculate kv on paper,but things like timing change kv.
neu uses a diffrent system,thats when you will see 1.5y or 1.5d etc (wye and delta winds)
but there also sensorless motors
sensored usually show a .5 wind (IE 13.5) were a sensorless will be a full wind 10t etc