Toonces the cat

Hi, so I am generally new to the sport of rc racing, and so I have decided I want to upgrade my Dominus 10TR (highly recommend checking it out) because it was my first rc. I currently run a 3500kV stock motor, but what kV can I run? Can I up the kV without burning the motor out? Just some questions I had I hope you guys here at the forums can answer, because I definitely do NOT want to buy a Castle motor and ESC and break the whole "kabosh."

Banshee8530

iTrader: (1)

This is actually more than just a "what motor?" Question. Since this vehicle uses 32 pitch gears, a smaller pinion should be fairly easy to find assuming the car uses a standard geometry pinion. When you go up in motor rating, you have to drop the pinion tooth count to avoid over-heating. When you go up in kV rating, you are trading torque for rpm so a smaller pinion is required to help the higher rpm motor get the car going.

Also, when you make the change from stock to a Castle set-up, you should consider going to a better battery and charger such as a lipo set-up to get the most out of your upgrade.

Those are just a few of the many considerations that must be addressed.

kodack10

I too am getting up to speed on the Brushless revolution. What I've come to discover is that KV isn't as relevant as I thought.

High KV motors tend to get you more power for the available battery. IE it will draw more amps, and deliver more speed than compared to a lower KV motor (all things being equal). However a low KV motor will tend to run cooler than a high kv. And a low kv motor can have the same RPM's as a high KV just by increasing the voltage and using more cells. The key thing is heat.

The high kv motor is going to put out a lot more heat. If it's 85% efficient, which would be very high, and it's pulling 100amps, that's still 15ampsx11 or 14 or 22 volts of PURE HEAT. The lower kv motor isn't going pull as many amps per cell.


So if you think about it, the limit to how much power you can put through a motor is how much heat it can handle before failing. The answer to that depends on the motor, the load, how well it dissipates heat, etc.

If you are wanting speed decide right now what kind of battery you want to use. If you plan to stick to 2 cell, get a motor high kv. If you plan to go to 3 or more cell, get a lower kv motor. It will give you more room to increase rpm's without as much waste heat.

Toonces the cat

Well, I saw that there was a rookie zone, and I thought a moderator would delete this one because it wasn't in the rookie zone

Toonces the cat

Thanks for that, that totally answers my question. I thought it would have to do mostly with what the limits are with how I want the car to perform (which is also understandably so) and what can be done.

Toonces the cat

Yeah, I saw a pretty handy post on the internet for what to do with your pinion gear when upgrading your motor. It says the same thing, that higher kV also means that a lower pinion gear will be needed