Are you looking to speed up your electric RC car to leave your competitors in dust down the local track? Or maybe you just want to have some fun racing a seriously fast electric RC car over the local park. Whatever the reason, this guide will give you some great tips on how you can go faster.
Depending on how fast you want to go and the amount of money you want to spend, there are a number of ways to speed up your RC car or truck. I’ll start with some of the cheaper options first and work my way up to the most expensive.
1. Change the Gear ratio
This is probably the cheapest way to alter the speed of your RC car. Simply change the pinion (the small metal gear on the motor) or the spur gear (the large plastic gear) for a different size. Change both of them for maximum effect. You will be surprised at how different the car feels when changing gear ratios.
For a higher top speed go for a larger pinion gear (with more teeth) and a smaller spur gear (with less teeth). The trade-off here is that you will gain a higher top speed at the expense of slower acceleration and a higher motor/esc temperature. This set up is ideal for long straight runs and large areas with few corners.
For quicker acceleration go for a smaller pinion gear (with less teeth) and a larger spur gear (with more teeth). Your car will accelerate off the mark very quickly with more torque, and you’ll also benefit from cooler running temperatures, extending the life of your motor and esc. The trade-off is a slower top speed. This is ideal for smaller spaces where you wouldn’t have the room for a long speed run, or where there are many corners or obstacles to race around.
Warning: Remember not to go too large with the pinion; the extra strain on the motor will generate a lot more heat, and your ESC or motor may even cut out – especially if you are using the car off road. The manual with your RC car should give you some recommended gear ratios and pinion sizes – or a search on Google should help you out. Experiment to get the balance just right.
2. Experiment with different tyres
Using the right tyres for the surface you are driving on will give the car more grip so you can make the most of the power available to you. This will help you get around the track that bit quicker. Tyres are very important; you won’t be going anywhere fast with no traction!
Slicks grip well on dry tarmac and road surfaces, full spikes work well on grass and wet mud, mini pins work well on carpet and astroturf, and mini spike are also a good all rounder.
The compound of the tyre will also need to be considered. Different compounds such as Schumacher’s Yellow, Green or Blue can be used. Softer tyres are good in low grip (loose dirt) and wet conditions, medium for dry and hard for very hot weather or long life.
There are many other different types of tyres out there, but that subject needs an article of its own which I’ll write when I get the time.
3. Reducing the weight
Reducing the weight of an RC car can certainly speed it up. You can do this by replacing heavy parts with light carbon, graphite or aluminium parts, lightweight wheels and body. If you run Ni-Mh or Ni-Cad battery packs, swapping over to Li-Po batteries is a great way to drastically reduce the weight of your car (Li-Po batteries also pack more of a punch, ideal for a high-end Motor/Esc combo).
The only downside to reducing the weight of your car is loss of traction. Less weight means the tyres aren’t pushing against the ground as hard, so you’ll find the car may not corner as well. If your goal is to achieve the fastest top speed possible then this won’t be a problem, although you may need to add a little weight to the front of the car to keep it from flipping over at high speeds!
4. Upgrade your Motor and ESC to a high power brushless system
Most ready-to-run (RTR) electric radio controlled cars bought in the shops are fitted with budget brushed or brushless motor systems to keep the price down. This is fine to get you started, but if you really want to push your car to its limits, upgrading your Motor and ESC (electronic speed controller) to a high performance system is a great way to do it.
By using a high performance brushless motor and ESC you can expect to see some pretty amazing speeds out of your RC car, with the added bonus of improved efficiency and longer run times that brushless technology has to offer. The motor and ESC you choose will depend on how fast you want to go, and the amount of money you want to spend.
High end motor and ESC combos such as Mamba Max or Novak GTB can be very expensive, often costing a lot more than the original car itself. If you don’t want to spend too much, cheaper Chinese systems such as Hobbyking or Turnigy are available and perform really well for the money.
Note on batteries: if you are running an extremely powerful Motor and ESC system, old style Ni-Mh or Ni-Cad batteries aren’t going to give you the power needed to run them to their full potential. When I first upgraded to brushless I was still using Ni-Mh batteries. Other than a longer run time I didn’t see an amazing difference in performance between a 6.5t brushless motor and my old 13t brushed quad – that was until I brought my first Li-Po battery – I was shocked at the difference! Even the old brushed motor showed a noticeable improvement in punch and speed. For this reason Li-Po batteries are highly recommended. Just remember to take care with Li-Po batteries; it is important that you charge and run them in the correct way.
What brushless motor system should you choose?
Brushless motors are usually rated by the number of turns (4.5t, 6.5t etc) or Kv (4600kv, 6900kv and so on) – I’ll explain more about that later, but for now, in a nutshell, the lower the turns, or the higher the kv, the faster the motor.
For 1/10th scale on-road use, the current fastest motor is around 3.5 turns (at time of writing this article – July 2012) which I think equals somewhere between 9000-10,000kv depending on what manufacturer you ask. For off-road use you would probably want a slightly slower motor; the extra amount of effort to move along on rough ground or grass is going to generate more heat and put more strain on the motor. The motor / ESC will end up overheating and cutting out, or worse case you may damage either the motor or ESC permanently.
Some example configurations for 1/10th RC Cars from Castle Creations
The guide below from Castle Creations gives you some examples of setups for 1/10th RC Cars and approximate speeds you can expect from their products. Note that the fastest possible combination on this sheet shows a slower Kv (5700 or 4600) motor with a 3s 11.1v Lipo pack or a 12cell Ni-mh battery pack. The 7700 or 6900 motor would be the faster option if you were limited to 2s Li-pos or standard 6 cell battery packs for some reason.
You can download a pdf of this guide here: http://www.castlecreations.com/support/documents/speed_and_gearing_chart.pdf