800kv vs 1100kv Brushless Motor for RC Cars [In 2024]

Last Updated on September 16, 2023 by Jaxon Mike

Choosing the right brushless motor is critical for getting the best speed and power from your radio controlled (RC) car. Two common options are 800kv and 1100kv motors. But what do these numbers mean and how do they impact performance? This article explains the key differences between 800kv and 1100kv brushless motors for RC enthusiasts.

comparison Table for 800kv vs 1100kv Brushless Motor for RC Cars

Specs	800kv Motor	1100kv Motor
KV Rating	800	1100
Max RPM on 10V	8,000	11,000
Torque	High torque at low RPMs	Less torque at low RPMs
Gearing Needs	Fewer reductions needed	More reductions needed
Efficiency	More efficient at lower RPMs	Less efficient at lower RPMs
Heat Generation	Runs cooler at low to mid RPMs	Generates more heat at high RPMs
Power Handling	Can handle more power	Lower power handling capability
Weight	Heavier construction	Lighter construction
Cost	More expensive	Less expensive
Applications	Large trucks, crawlers, high torque needs	Smaller/lighter trucks and buggies focused on speed
Price	Check Latest Price	Check Latest Price

What is KV Rating?

KV refers to the RPM constant of a brushless motor. It represents how many RPM the motor will theoretically spin per volt applied. Higher KV equals more RPMs per volt.

For example, an 800kv motor running on 10 volts would spin at:

800 x 10 = 8,000 RPM

While a 1100kv motor on 10 volts would produce:

1100 x 10 = 11,000 RPM

So a higher KV motor will have a higher no-load maximum RPM on the same voltage input. KV rating along with battery voltage and gearing determines a vehicle’s top speed.

800kv Motor Characteristics

• KV rating around 800 (RPMs per volt)
• Provides good low-end torque
• Lower maximum RPM limit
• Needs fewer gear ratio reductions
• Generates less motor heat
• More efficient at lower RPMs
• Better for heavier models like the XMaxx

An 800kv motor has a lower KV constant, so it spins slower for any given voltage. This makes it better suited for larger RC cars like the Traxxas XMaxx that need low-end grunt to move their weight. The XMaxx comes stock with an 800kv Velineon motor for this reason.

1100kv Motor Characteristics

• KV rating around 1100
• Provides less torque down low
• Higher maximum RPM capability
• Needs more gear reductions to limit RPMs
• Generates more motor heat at high RPMs
• Less efficient at lower speeds
• Better for lighter/faster RC cars

A 1100kv motor has a higher KV rating, so it can spin much faster on the same voltage input. This allows smaller RC cars to achieve higher top speeds. But less low-end torque means it won’t provide as much pulling power for heavy models.

Torque Comparison

Torque is a key performance difference between 800kv and 1100kv RC motors.

Higher KV motors inherently produce less torque for a given power input. Since torque = power divided by RPM, if KV raises RPMs, torque must drop to maintain the same power.

800kv motors maximize torque by spinning slower. Their lower KV rating keeps torque higher at lower RPMs. This helps heavier vehicles like the XMaxx accelerate and climb.

1100kv motors sacrifice torque to reach higher peak RPMs. Better for smaller/lighter RC cars focused on high speed rather than low-end grunt.

Gearing Impact

Gear reduction ratios must match the KV rating to optimize efficiency.

Higher KV motors need more gears to reduce RPMs and prevent over-revving. This increases drivetrain losses.

Lower KV motors need fewer gear reductions to limit RPMs. Less parasitic losses improve efficiency and runtime.

The XMaxx’s 800kv motor only needs 2 gear reductions to reach reasonable speeds. This improves efficiency and torque delivery to the wheels.

Heat Generation

Higher KV means higher RPMs and more heat. As motor RPMs climb, internal energy losses soar exponentially.

800kv motors run cooler at typical RC car speeds. Less heat means lower failure rates and added reliability.

1100kv motors generate substantial heat at high RPMs. Requires careful gearing and cooling airflow to avoid overheating damage.

The XMaxx’s 800kv motor stays cooler during high-load, low-speed crawling – one reason it’s the factory choice.

Efficiency Comparison

Motor efficiency varies based on speed and load.

800kv motors achieve peak efficiency at lower RPMs under load. Makes them ideal for high torque RC applications.

1100kv motors are optimized for top speed, not low-end efficiency. Poor efficiency at typical crawling speeds.

So 800kv motors like the XMaxx’s will use battery power more efficiently during low speed technical driving.

Weight and Power Handling

Higher KV motors must be built lighter to achieve those high RPMs. This also limits power handling.

800kv motors can utilize heavier construction to produce higher torque and handle more power.

The XMaxx motor must handle over 20 lbs of heavy vehicle weight plus punishing jumps and crashes. Its 800kv design generates torque and survives abuse.

A lightweight 1100kv motor would burn out quickly under the stresses of a maxx truck like the XMaxx.

FAQs

Can I run a 1100kv motor in my XMaxx?

It’s not recommended. The 1100kv would lack low-end torque and efficiency. Gearing changes could help but may overheat. Stick to 800-900kv for the XMaxx.

Is a higher kv motor always faster?

No. The top speed depends on kv rating, voltage, and gearing. A lower kv motor geared properly can match higher kv top speed.

Do I need a sensored motor?

Sensored motors have timing sensors for better low-speed control. This helps big trucks like the XMaxx. But sensorless brushless motors work too.

Can I rewind a motor to change kv?

Yes, companies offer rewinding services to alter kv ratings. But it’s often cheaper to just buy a new motor with desired kv rating.

What causes brushless motors to burn out?

Overheating from too high kv or overgearing is the main cause of failure. Quality construction also prevents early breakdowns. Keep motors cool!

Conclusion

For heavy, high-torque RC vehicles like the Traxxas XMaxx, an 800kv brushless motor is the best match. The 800kv design provides lots of low-end torque for quick acceleration and climbing while also running efficiently with less heat. This gives the right blend of power and reliability to handle an RC monster truck’s demanding operation.