1/3 Scale Hybrid RC Car With A Scratch-Built 125cc V10 Engine

Scale model engines are fascinating pieces of engineering, and RC cars are always awesome to play with, no matter your age. [Keith57000] has gone over the top on both, creating a seriously impressive hybrid RC car built around a custom 125 cc V10 engine.

[Keith57000] started building the V10 engine back in 2013, after completing a 1/4 scale V8. The build is documented in a forum thread with lots of pictures of his beautiful craftsmanship. Most of the mechanical components were machined on a manual lathe and milling machine. No CNC, just lots of drawings and measurements, clever use of dividing heads, and careful dial reading. The engine also features electronic fuel injection with a MegaSquirt controller.

The rest of the car is just as impressive as the power plant. The chassis is bent tube, with machined brackets and carbon fiber suspension components. Two electric skateboard motors are added to give it a bit more power. The three speed gearbox is also custom, built with gears scavenged from a pit bike and angle grinder. It uses two small pneumatic pistons to do the shifting, with a clever servo mechanism that mechanically switches the solenoid valves. Check out all fourteen build videos on his channel for more details.

An amateur project of this complexity is never without speed bumps, which [Keith57000] details in the videos and build thread. It has taken seven years so far, but it is without a doubt the most impressive RC car we’ve seen. His skill with manual machine tools is something we rarely get to see in the age of CNC. We’re looking forward to the finished product, hopefully screaming around a track with a FPV cockpit.

18 thoughts on “1/3 Scale Hybrid RC Car With A Scratch-Built 125cc V10 Engine

  1. The servo driven rotary microswitch thing has to be the most gloriously over-complicated way to convert a hobby pwm signal into a relay output.

    It is great to see the engine running again! And running great by the looks of it! Way more satisfying then the electric drive he had been working on

      1. You fail to realise he is servo shifting a 4 speed dog box and the switches are shift state readback.
        Suggest a simpler way of remotely shifting the gears and knowing what gear you are in

    1. RC hobby people do that kind of thing all the time. Can’t blame them for not knowing another way of solving the problem when they’ve solved so many other problems and got something working.

  2. The engine alone would be pretty incredible, but, the build as a whole, it looks and sounds great.
    I’m always a little, in awe, of people who, can keep a steady enough hand, required to, build anything that intricate and tiny.
    Next up, a scale six speed synchromesh box [ plus reverse ], maybe a viscous clutch too?

  3. Ridiculous amount of craftsmanship and skill. Gives me similar feeling to people farting around with carbureted engines nowadays. At the end of a day still slower product than electric skateboard without all that extra added weight.

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