How Do You Build An RC Dragster?

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Question: How Do You Build An RC Dragster?

In the RC world, there are two types of drag racing: on-road and off-road. RC dragsters, by design, are made to go fast. On-road RC dragsters are made to go fast, in a straight line, down a level paved track that's about 132 feet or so long. There are no hairpin turns or going around on a circle track in RC drag racing. Drag racing is all about a fast burst of speed and horsepower. Then you have the dirt drag with off-road RC dragsters. The object of dirt drag racing is to go down a straight track roughly about 66 feet long made of dirt as fast as you possibly can, pushing an off-road RC dragster to its limits.

Answer: When building an RC dragster, the first two considerations are whether you are building an on-road or off-road dragster and whether you want an electric or nitro RC dragster. After that it's primarily just a matter of cost -- pricing out parts and estimating what it's going to take to build or convert an RC to a dragster.

Off-Road RC Dragsters
This type of dragster has big, dirt grabbing tires on the back and sometimes on the front if the RC is all-wheel-drive. Dirt dragsters also have high torque motors electric motors or nitro engines to get them down the track as fast as possible. Since aerodynamics isn't an issue you can use a monster truck, truggy, buggy, or even rally cars for a starting point when making an off-road dragster. All that would be left to do is build it up for speed and traction, after all you are racing on loose dirt.

On-Road RC Dragsters
This is the more traditional type of dragster. Long and lean, on-road dragsters also have high torque motors. They too have big tires on the back but they are called drag slicks since they don't have a treaded surface -- it's smooth. To get traction on the paved track, the RC dragsters have a tacky-glue like compound added to their tires that give them the traction needed to get down the paved drag strip as fast as possible. The drag strip itself is sometimes coated as well.

Areas of Concern on RC Dragsters
Since both versions are dragsters and are similar here are the primary areas to research whether you are building your own from scratch or modifying an existing chassis and or components.

  • Motor / Engine
  • Drivetrain (gear ratios)
  • Suspension
  • Aerodynamics
  • Tires
  • Chassis
  • Modifications

Motor / Engine. f you decide to go electric you would probably want a brushless setup that can handle a large amount of voltage of around 11-14 volts depending on the class you run. If you have chosen to go nitro then you want to go with a big block style engine and a high nitro content fuel of around 20-30%.

Keep in mind that the bigger the motor the more stress it puts on the drivetrain.

Drivetrain. The drivetrain is what gets you down the strip. Either way, dirt or pavement, you want to get to the end before your opponent. So tuning and tweaking to get both speed and take off is a skill that you will be learning to master. Gear ratios play a big part in that skill. So brush up on your math skills you're going to need them.

Upgrading parts such as drive axles and replacing plastic gears with metal ones in the gear box wouldn't be a bad idea either.

Suspension. Since your vehicle will be moving at a high rate of speed you will want to make sure that your RC dragster stays on the ground. Even though it looks like smooth pavement it isn't -- there are still bumps that could send your RC dragster soaring through the air and inevitably crashing down to the ground and taking you out of the competition. Having a good suspension setup will keep this from happening.

Speaking of keeping things on the ground, this brings me to the other point: aerodynamics and controlling the air around your RC.

Aerodynamics (wings and things). This really doesn't apply to off-road drag racing. It's more applicable to on-road drag racing. Aerodynamics helps keep your RC dragster blazing down the strip by having some sort of wing to provide down force from air passing over the body. Furthermore, having a streamlined, low mounted body (low to the ground) helps by preventing air forces from robbing your RC from getting the best possible times.

Tires. You're going to want the best traction possible in both versions of drag racing. On an on-road dragster, you are going to want to have a set of good quality foam or rubber on-road tires. Foam is commonly used because of their generally better traction over rubber tires. When it comes to tires for off-road drag racing you want to have the best tread pattern possible, for example, paddle tires would be a great choice for their ability to dig down deep in loose dirt or sand.

Chassis. This a very important aspect of drag racing. Remember the object of drag racing is to be the fastest RC dragster in the competition. You can't be that if your RC weighs as much as a ton of bricks. Too much weight on your RC can drag you down -- that's not what is meant by drag racing. Having a light-weight chassis made from carbon fiber or light-weight metal tubing will give you the results you are looking for.

Still not fast enough for you? Well, there's always modification.

Modifications. Modding is a fun part of any RC building project. Modding is about taking the parts (stock or upgrades) and making them do things they weren't originally intended to do. Some engines just won't mount up. Make them fit by building your own brackets and mounts. When it comes to nitro engines, porting and polishing is a great way to boost performance. This could break your pocketbook though. If not done properly you could find yourself buying a new engine. Electric motor modding is known for taking a motor apart and redoing the windings and adding stronger, more higher quality magnets then reassembling it. With the new winding and magnets, you can get better torque and the ability to pump more voltage into them.

This is an overview of what you need to know when building or upgrading/modifying an RC to be an on-road or off-road RC dragster. See some of the links, below, for more detailed instructions on RC dragster building or parts for RC dragsters.