Selecting the right electric motor for your Arrma Limitless can feel overwhelming, especially for beginners. With various factors like motor size, speed, and cost to consider, making an informed choice is crucial for optimizing performance.
Size is paramount because not all RC electric motors can fittingly sit inside a stock Limitless chassis. Speed refers to the overall performance of the motor in terms of torque and RPM, while price is where we want to extract the most value from.
Thus, we thought we should break some sweat to present a practical guide on the best motors that have been tried and tested on an Arrma Limitless V2 with a single motor.
Why Use Brushless Motor
First of all, one may ask why must we use a brushless motor rather than a brushed version. A detailed explanation of what is a brushless motor is beyond the scope of this article, but to keep things easily comprehensible, a brushless motor is a lot faster than a brushed motor simply because it does not use brushes. We can all imagine that brushing a motor creates friction and hinders its rotational speed. This is exactly what happens in a brushed motor. It uses carbon brushes to deliver electrical current to the motor’s rotating part, called the rotor.
A brushless motor, on the other hand, does not have brushes which efficiently makes it faster. There are other features that make brushless more ideal for racing but for now, it should be clear that we only want to use brushless motors to go full speed ahead.
TP Power 4070
TP Power is a well-known electric motor manufacturer in the radio-controlled fraternity for producing cost-effective brushless motors for RC surface vehicles. Its 4070 brushless motor is popularly used in the Formula 1 vs. RC car drag race hosted by Carwow – an online marketplace to trade cars.
TP Power 40XX motors have a diameter of 40mm. However, the XX does not represent the length. For example, 4070 motor body length (excluding the motor shaft) is actually 107mm, NOT 70mm.
This company produces probably the fastest RC motors for speedruns and its 4070 is one of our most recommended motors for stock Arrma Limitless chassis. James McCoy, the RC world record holder, has the video below depicting his 179mph (288km/h) speedrun with a single TP Power 4070 motor.
TP Power categorizes its brushless motors into different variants – CM, SCM and SVM. CM stands for Competition Motor while SCM is Super Competition Motor where “super” means faster than the traditional CM. The fastest of all variants is coined SVM – Super Velocity Motor – where it offers a great amount of torque and is able to handle high RPMs.
TP Power 4070 motors usually support up to 6s or 8s LiPo batteries. Please check the product specifications
Typically, to achieve blazing speeds, you should be using motors with higher kV. Anything above 2,000kV is the standard for RC racing with TP Power motors.
TP Power 4080
This 4080 variant is the successor to the 4070 motor. Before you consider purchasing a 4080 motor from TP Power, do note that it can’t fit into the stock chassis of Arrma Limitless V2 due to its longer 117mm body length compared to the 4070.
To fit, you need to modify your chassis by flipping the motor mounting bracket so that the motor can be attached while facing the front. This means the pinion gear attached to the shaft will be facing forward instead of the typical backward direction. See the yellow box in the image below which illustrates the imaginary location of the 4080 motor. You also need to move the left battery tray to the front of the chassis.
James McCoy has done numerous speed runs with a single 4080 motor and attained a career best of 198mph (319km/h), as demonstrated in the video below. However, we’ve seen many speedrunners using this motor in a dual configuration to achieve jaw-dropping speeds of more than 200mph.
TP Power 4090
This longer motor from the TP Power family is supposed to the better and faster than the 4080. However, because it is still new in the market, we have yet to see anyone testing it on an Arrma Limitless. The length of its can is 127mm while maintaining the 40mm diameter dimension. It is claimed to be able to produce a maximum power of 13,300W and a maximum of 55,000 RPM. And as crazy as it may sound, it is supposed to support up to a whooping 23s LiPo battery!
We shall eagerly update this article once we have more info about the actual performance of this unbelievable motor on a Limitless.
Castle 2028
A powerful brushless motor from Castle Creations, the company that also produces the high-end Mamba XLX 2 ESC. It is bigger than TP 4070 with a diameter of 56.3mm and a body length of 112.7mm and it can support up to 12s batteries. Due to its sheer size, you need to use the 56 series motor mounting plate on a Limitless that is sold separately. The stock mounting plate just wouldn’t cut it.
Castle Creations motor’s naming convention relies on the size of the motor stator – the center part of the motor that is not rotating that contains the coils – not its overall dimension. For example, Castle 2028 means the stator has a diameter of 20 inches and a length of 28 inches.
Below is a Limitless speedrun video with a Castle 2028 1700kV motor achieving a top speed of 178mph (286km/h).
Castle 1721
This is a more affordable motor from Castle Creations that also packs a punch. It fits nicely in an original Limitless chassis. A 2,400kV model has reached a top speed of 193mph (311km/h), as shown below. It can support up to 8s batteries.
Castle 1717
This is probably the smallest Castle brushless motor commonly used on a stock Limitless. We have seen multiple speedruns with the 1,650kV version reaching speeds of 135mph (217km/h) or 109mph (175km/h). It too can be used with a maximum of 8s LiPo batteries.
Hobbywing EZRUN 4985
One of the least expensive brushless motors that have been tried and tested on Arrma Limitless. It can accept up to 6s LiPo batteries and has a diameter of 49mm as stated in its model name. It can fit nicely with the stock motor mounting plate. Some have their Limitless reaching 111mph (179km/h) with the 1650kV.
Speed Comparison Table
If speed is not everything, but the only thing, then this table below deserves some attention.
Please note that the speeds compared above are not entirely based on the stock Arrma Limitless chassis. Other parts of the car, such as the quality of batteries, tires, differentials, driveshaft, ESC, body shell, aerodynamic parts, and more, need to be considered to obtain breakneck speeds, pun intended.
