Relationship of RC Brushless Motor Power Output 

Hey Ryan, thanks for the comment! I'm glad they make it easier to learn!

Yes, what specifically were you hoping that I talk about in the video?

Best gears for 4370 kv motor redcat nascar

@@RCexplained I think for speedrun guys going over which motor to choose would be a good place to start (high KV low volt conservative gearing, vs low KV high volt with aggressive gearing etc). I know picking a battery is the first thing you usually want to do and work back from there

Thanks for the comment. I can and have one already in queue. What specifically were you looking for me to talk about?

Hi Mark, What does long run times mean for you? A long run time to me is 6 minutes. You could use a 36mm x 64mm or 36mm x 74mm motor around 1500kv on 4s to achieve the speed. As for run time you would need to bump the mAh up for the pack to hit the run time you are looking for.

@@RCexplained Hey thanks for the reply so you can better understand I was looking to power a vessel something like this ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Bo5nTgmPXaw.html I was wondering what size motors and battery could approach the run time claimed in this video. I can go twin engines if I have to too. Thanks man!

The motor above will get you close to the speed you are looking for. Run time will be tough. You will not be able to travel at top speed for that long. At the same speed as shown in the video you can achieve similar run times. I updated the kv of the motor in the previous comment.

Waste heat is related to the efficiency of the motor and how much power is being asked of it to deliver. Surface area can be calculated for any given motor size.

Thank You!

What LiPo would be used on each motor?

@@RCexplained 1/8 scale racing is 4s lipo. Most of the time I use 5000mah capacity

Hi Greg. This is not an easy question to answer, I like it. I would expect in your example the race is for endurance and not maximum power output. To make a proper comparison, each motor would have to be physically tested in the application. I would expect (an assumption) and its very likely the smaller motor would have a lower Rm and Io value. Since you are not taking advantage of the lower kv value through higher voltages, it's very possible that the smaller motor would be more efficient in its power delivery. If each motor is geared to travel at the same top speed, both motors will have to output identical wattage to hit those same speeds. This equates to approximately the same input currents to the motors. The larger motor with a higher Rm value will produce more waste heat from copper losses. It will also produce more waste heat from iron losses. If the larger motor can dissipate this waste heat, it will be able to operate at this power output. However, because of the losses, more power will have to be input for equal output power. Every motor is different and the only way to make a proper comparison is actual tests. In addition, looking for these improvements in efficiency through tests will be quite difficult as the difference could be quite minimal. A very well planned and executed experiment would have to be used.

@@RCexplained i have tested a 4074 1550kv motor at 4s compared to 4074 2200kv motor and results is the 1550kv motor runs cooler and runs longer on the same battery at the same speed from gearing . So im thinking a big 4092 lower kv motor will allow me to race long 30min races with the nitro buggies

@@gregstafford2155 When you tested the 1550 vs 2200kv motors, was the output at the wheels geared to the same speed?

What are your goals?

@@RCexplained To have some more speed and battery life Nothing else Thank you for your answer

I'm not familiar with that particular RC boat. However, if you are able to understand the size of the motor it's using, you could get an equivalent brushless motor. Do you know the size of the motor in the boat? Diameter and length in millimeters. I'm assuming it's brushed, 2 wires from the speed control are routed to the motor.

@@RCexplained The size is 13.00* 7.00*4.00 End is 1100kv Yes , with 2 wire.

The dimensions you have provided are in millimeters?

What impeller and cell count will you use?

RCexplained impeller is from a guy called Mark from Youngesters jets channel, it's 53mm and the voltage is 6s

Hi Rama, Inrunners and outrunner are both quite powerful.

@@RCexplained Outrunner r more powerful coz of the long lever from center. Which inrunner has short lever from centre.