Does Increasing the Motor Kv value Increase an RC Cars Top Speed?

In this video we break down increasing kv in order to increase the top speed of an RC car. What are our options to increase the top speed of the RC car and how do we accomplish this with the most success possible? in the video we use an RC Car as the primary example, however, the same principles would also apply to RC Airplanes and RC Boats.

Two scenarios play out. In scenario one we are using a 2200 kv motor as the base motor but asking the question - would increasing kv to the 2650kv motor increase speed? Does the answer change if we knew that the 2200kv motor was at a thermal limit? How about if we know that the 2650kv motor we wish to use is a smaller length?

Let's use what we learn from scenario 1 and apply it to scenario 2.

In Scenario two (where I show the buggy and its motors) we look at the case where the smaller motor with the higher kv is now at a thermal limit. This is the exact same idea as in scenario one applied here too. The best case scenario to improve reliability and increase speed is to move to a larger motor getting away from thermal limits.

Here is a link to an article on the same topic with a few more details:

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[lawrencewinter]

Hi guys, some useful intel in there for me. I'm totally new to the hobby, but I teach Physics at a high school. It's my understanding that the rotating magnet in the brushless motor will generate a back EMF which is in fact the limiting factor in its top rotational velocity at a given voltage. The more turns in the motor will increase the back emf at a given RPM which is why higher KV motors have lower turns of coils in the motor. Lower KV motors deliver much more torque at low RPMs but cannot reach high RPMs because they quickly generate a back EMF as RPM rises. Higher KV motors have fewer turns - which gives less force (torque) and so the acceleration is less but the top end is more. It may be useful to mention this too. Unless I'm horribly mistaken - forgive me if so.

[thumpr]

these videos are the best info ive heard in years for rc!! DONT STOP!

[kingrc]

Thanks a lot man you're like an RC professor was looking for someone to tell me the science behind the RCs 💯

[humlakullen]

Can’t believe I just discovered your channel… Absolutely awesome work.
Thanks a million!

[dnml]

I think what you're trying to say is that the light that burns twice a bright, burns half as long....

[NabiL_Lam]

Thank you for teaching us how to make our rc cars faster

[joeyboy]

Very informative. Thanks for the great review. Hope this channel really grows. Subscribed.

[scaleworksRC]

Awesome breakdown. I'm new to speed running and just now in the 70s. My ESC has motor timing settings that I could play with, but I still need to learn more before I change anything.

[bryanbolich]

There's more to it then that. Like amp draw, power to weight ratio, WATTS power of the motor. Higher Kv uses less voltage but more amps in order to get closer to the (Watts) actual power. But also shortens the run time. The specs show it all. Look at the volts and amps on the specs. Lower kv doesn't just mean longer run time. It means it requires more batteries then higher Kv motors to reach it's true WATTS OR POWER you need for faster speed.

[rcyalater...]

Learning so much. Don't ask why it took so long to subscribe. Keep up the great vids!

[rcbustanut]

This is excellent info bro😎👍

There are however motors out there that can handle the issue most higher kv motors have, which like you mentioned, is that they have smaller can size & overheat quicker. TP power motors have a nice selection of higher kv motors with large can size & capable of handling higher voltages & current than most common motor companies offering the same kv value.

I'm in the middle of working on a 4S high speed project, an Arrma Typhon 6S stretched build. Castle XLX2 controller. While the XLX2 can handle 8S & I can easily get this car over 120mph running 8S, I realized that I can run a higher kv motor, with a decent current rating, on half the voltage & still achieve high speeds & not worry about the too much current being pulled from the ESC, since the XLX2 can handle over 500A. I ran as a test an old hobbywing ezrun 2200kv motor I had on this new stretched Typhon 6S with a 34T/34T gearing on 4S. Pulled 207A from the ESC & hit 85mph. Did 3 runs back to back @85mph & i could still keep my fingers on the motor. My gear calculator estimated 86mph with this setup so I definitely was hitting max on my runs. Even with this "not top of the line" 2200kv motor, with a minor gear change & still running 4S, I should be able to get over the 100mph mark. Next motor will be either a TP Power motor or the Castle 1721 2400kv motor. Looking forward to breaking ~110mph on 4S. I know it's possible & even higher as others have already done so.

[madpengu]

You never mentioned adding a heatsink. It is a good way to reduce heat without having to upgrade the can size.

[cobrakilleridis]

yes buddy, you are a big helper for understanding more things around RC hobbies.
keep that way!!!

[lexhtfdct]

What's a good ESC, motor, spur, pinion set up for my XMAXX for bashing, 80mph, cool temps and battery

[tedsimington]

Thank you so much that was very informative👍

[foellerd]

Oof, I recently put a 4370 KV brushless motor in my 1/10th scale Redcat Volcano. With it I put in a 60 amp ESC that has a fan on it and use a 50C 2S battery with 5200mah capacity. Basically I did all this before watching this video and have some concerns now. Haha. Im about to head to you brushless motor hesitation video since this setup struggles with that issue badly. Learning alot quickly right now. Thankyou good sir.

[jimmyv]

Well there is actually a lot more to it than simple RPM. You can actually increase your top speed by lowering the KV and increasing the gearing. I’m curious to see your results because I’m going to be running the same experiment. Going from a 2050kv to a 1700kv swapping the gear to a high speed gear and see what happens

[tonya]

Seems simple enough, I just wonder why sounds so complicated!

[remkojerphanion]

Another good video, keep 'm comin' !

[Rcjamaica]

I hve a wltoys 124017 i want to use 3650 and a 4s esc .what kv do you recommend please ..and yes i want it to be a speed run car