new boy with question for speed t owners

[dean]

hi all
ive just got my speed t which is great... my question is, if i upgrade the motor to the 7500k version, do i need to change the esc or can i use the standard one. i run my car on an airfield so ive got plenty of room for the high speed and lots of perfect tarmac runways :)

[snoking]

What are you running for batteries. The SDT will take a 3S Lipo and they claim 65MPH. Lower KV motors and bigger batteries result in high RPM's. Not sure the higher KV motors can take a 3S battery.

Not sure you are looking at it correctly.

Chris

[swalker]

The ESC should be ok, but dont forget that the higher the kV raiting, the lower the torque the motor will produce and so the smaller the pinion gear that you can run.

It is not as simple as twice the kV and so twice the speed.

[Clint B.]

there is a formula to figure out what rpms you would get from batts and motors... Too bad i cant recall how to do it at the moment.
im am 100% sure that motor wouldnt handle 3s voltage it would spin so fast it would rip the magnets off rotor. not 100% sure but i think about 5400kv (about an 8.5 sensored) is most kv that can handle that kinda rpm
that 7500kv motor on 2s would probabally be close to the 4800kv on 3s but the 7500 would be toasty hot and would be harder on batts. ive heard your get more power and more run time from lower kv motors on more cells because its puss less strain on everything yet your running at same rmp.
Oh yea if you do get a 7500 get a temp guage (fingers dont work 120 feels hot when its not)and some pinions also these things like to run in the 160ish range dont go over 180 if possible and 200 is the point stuff starts to break

[XCELORIN]

Hey Clint.B I have a Quick Question? I have a 4800kv on 3c and i drive on road only.what gearing is best u think for the motor?

[Clint B.]

i think below stock should be in your range. then you can add teeth to the pinion until motor or esc get 160+

[BLUESTAR502]

On my speed t i run 18 pinion stock spur stays nice and cool if you run with a higher pinion keep an eye on the motor heat and a close eye on your esc it is known to get pretty HOT. Iforgot to mention that is running a 3s 11.1 5000 mah lipo

[speedster1919]

High KV motors can't take the 3s and 4s batteries because the bearings can not take that high RPM. The reason they offer 6000-7000KV motors is to get the most speed from a 2 cell battery that will fit most chassis. At 70,000 rpm the bearing have no chance to survive.