What's better for more speed?
 

I have a HPI Sprint with a 3930kv brushless motor currently and want to do a major speed run just to see what it can do. Would it be better going to a larger ( 36x74 ) can 2800kv motor and running a larger pinion on 4 or 5s or stay with the 36x50 normal 540 size can with a higher kv and 2 or 3s? Also assuming the larger can is more powerful would it stay cooler under the same conditions than the smaller motor? If there are questions as to "how fast", well I don't know. I just have a little money to burn and want to mess around. I also have a 10 scale truck to put the larger motor in after my experiment.

Thanks for your input!

Speed needs power and you are always going to get more power by increasing the voltage.

it depends on your speed controller too.

or your gearing.:D

Don't exceed the max safe RPM for your motor. 4s or 5s may generate way too many RPM for that motor, grenading the rotor and destroying the motor.

Yeah I will be watching closely these things. Which route should I take though?

All of them. Highest KV motor you can get (12000 +), 150A + esc, 6S + lipo, and gear it to hell, 32 pinion and 52 spur. LOL.

is it rubber burning that I smell ?:D

Who makes a motor that can handle that rpm? I've not seen one.

LRP Vector X12 Brushless Modified - 3.5t 10,000KV @ 76000RPM as a start, but there are others out there capable of even more frightening speeds.

If you are really serious about getting into speed, the best place to start would be with your local RC Drags Association or RC Speed clubs, then work out a budget and start from there.

I have an RC Funny Car with a 5T motor running 6S and its insanely fast, i could ramp it up a lot more using boost and timing, and take it out to 10S, but super speed is not my thing, consistency is and heat is not an issue when a race is over in 2 seconds so you can do insane things.

I see ok. That's not really what Im going for. Just want to see what it can do once or twice. Kind of just to show off. Not looking to send a ton of money. Im at 50mph on my current setup. Ill just try for a little more.

Then the cheapest thing you can do is change your gearing, pinions and spurs are cheep and easy to install, you should be able to get an extra 10mph that way pretty easily.

Maybe I'll do that. I'm definately getting another motor though because I wanted to put it on my Esavage. hobbypartz says their 36x74 2800kv motor is 8 scale. Wanted to put that in my Sprint and gear it stupid! lol But people are telling me I'll get more speed out of something else.

There are 2 ways to do it, low voltage and high KV motor, IE: 7.4v (2S) and high KV motor 7200KV motor, or high voltage 14.8v (4S) or higher and low KV motor 2200KV.

TC on road is the former due to rules and off road buggies are generally the latter. So if you get that motor, you need to ramp up the voltage to get the most out of it.

I just bought a 5900kv motor that can handle 3s. Will get me to about 75k rpm which according to the calculators will get to 94mph with the gearing I have. Now I realize the calculators are off somewhat but if I could get 80+ out of it I'd be happy.