Monday, July 16, 2012

Combining a Nitro Motor or High Powered Motors with Mindstorms and a 8070 Super Car

I have always wanted to make a Technic super car. I have gotten close in my own way, but I never fully built anything that truly satisfied me. In my mind, I have always wanted a Lego Super car that could travel at or near highway speeds. As it turns out, ganging Lego motors can only go so far.

A Hobby Aircraft Motor
In contrast, a hobby electric aircraft motor would do very well as the main driving motor to propel the car at warp speed. I want to get one that puts out around a horsepower or more. If I used this solution, It will be controlled by a Mindsensors NXT Relay Driver. Moreover, the NXT will control the NXT Relay Driver which will control another relay for high power use that connects the motor to the battery. This solution would be simple and avoid the need to use a proper motor controller, however, the sudden torque might snap the Lego pieces. It might be necessarily to get a high current motor controller to try to smooth out the sudden onset of torque.

A Nitro Motor
 The other option would be use an actual nitro motor. This is an example of a nitro motor that I would consider. I would totally be cool with this if it doesn't melt anything and I can find one small enough to fit in the car. It looks like the really cheap ones are 50 bucks a pop. I would be totally new to this side of the hobby. This would be mixing the geeky Technic side with the shiny semi custom RC car side. This really should happen sooner rather than later. I would have the NXT control a motor which actuated the throttle. I think the nitro motors like these have a centrifugal clutch which would be perfect for this application. It will let the user slowly apply torque to the drive train without snapping the parts. In addition, it will also let the car idle and not creep. I did design a heavy duty differential in CAD that I am going to 3D print eventually. It uses 4 knob wheel gears since they are the strongest type of gear Lego has. It also has bearings to help everything run smoothly. One day I might have a nitro motor abusing one of my heavy duty custom differentials :)

You might be curious how I am actually going to connect any of this to the Lego system itself. I am getting a 3D printer, and I am going to print the parts I need to get either the electric motor or nitro engine mounted into the car. I also have a small hobby lathe, drill press, and mini CNC mill to help me accomplish this project. Lets hope the propulsion system doesn't melt whatever it touches. If it does, this might end up being the first liquid cooled nitro Lego car.
Lego's 8070 Super Car

The platform that I am thinking about modifying is an 8070 super car. My mom gave it to me for my 23rd birthday. Thanks mom! It has some pretty nifty features that I would like to preserve. It has "lambo doors", a pop open hood, a pop open rear spoiler, steering, and propulsion. It also has one of Lego's moving decorative engines under the hood, but I don't really find that overly amusing. It is going to get replaced by an actual engine of some sort. In the stock setup, all of the functions are actuated by a medium motor mated to a Lego transmission, and moving the stick around in the drivers area changes what function the medium motor actuates. I was studying the directions last night to see how easy it would be to change everything. Lego did a great job integrating everything together which will make this a bit of a pain to modify. The transmission is the centerpiece of the model; it is where the magic happens to make all the functions work. I would remove the transmission, and try to motorize the functions individually so that the NXT can control the functions. It looks like most of the functions operate with a worm-gear type setup which moves a crank and then a set of linkages. It might be possible to replace the crank and linkage setups with some Lego pneumaticsThere are some minor features that I want to add too. One thing that super cars ought to have are working headlights, and I will add some remote control functionality with a Mindsensors PSP-Nx-4c. That will give me a slick user interface and lots of buttons to control the other functions of the car.

In summary, this is really going to take the term "super car" to the next level. An actual source of torque such as a hobby aircraft motor or nitro engine paired with the intelligence of an NXT will make  an extremely fast, one of a kind, and programmable machine.


  1. I'd go brushless electric with a dedicated speed control... Not as messy for one, not as hot for another. nitro engine are loud too. Lithium polymer batteries are cheap and light.

  2. @Brickmodder, do you have a recommendation on a motor/controller combo?

  3. Were do you get a 3D printer and for how much?

    1. do you have a recommendation on a motor/controller combo?

      I ordered a Solidoodle.