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Making a DRIVETRAIN and Installing the Micro V4 ENGINE on the RC Car!

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A tiny four-cylinder engine is about to get its own drivetrain, built entirely by hand.

JohnnyQ90, the YouTube machinist known for scratch-building working miniature engines, is back with the next chapter of his most ambitious build yet: a fully functional, fuel-powered RC car running on a custom-fabricated 14cc V4 nitro engine. His latest upload, “Making a DRIVETRAIN and Installing the Micro V4 ENGINE on the RC Car!,” picks up right where bench-testing the standalone engine left off, moving the project from “does it run?” to “can it actually drive?”

• The project centers on a custom-built 14cc miniature four-cylinder, four-stroke V4 nitro engine — not an off-the-shelf electric motor.
• In this episode, JohnnyQ90 fabricates the entire drivetrain by hand, custom-fitting gears, couplings, bearings, and drive shafts to carry power from the engine to the wheels.
• The video marks the bridge between standalone bench testing of the V4 and full integration of the drivetrain, chassis bracing, and radio electronics needed for a driveable model.

From Bench Test to Rolling Chassis

Anyone who has followed JohnnyQ90’s channel knows the drill: an engine doesn’t count until it’s actually turning wheels. The Micro V4 had already proven itself running freely on a test stand in earlier installments, but a nitro engine spinning in open air is a very different problem from one bolted into a metal chassis and expected to move a car. This episode is where that transition happens, with JohnnyQ90 machining the mechanical path that gets combustion power out of the crankcase and onto the ground.

That means building out a gear train and shaft system capable of surviving the vibration, heat, and torque pulses of a real four-stroke engine — a much harsher environment than a brushless electric setup found in most hobby-grade RC builds.

Custom-Fitting the Drivetrain

Rather than buying an off-the-shelf transmission kit, JohnnyQ90 machines the drivetrain components himself — gears, couplings, bearings, and drive shafts all custom-fitted to the chassis and to the V4’s output shaft. Every part has to be sized precisely so the engine’s power transfers cleanly without binding or excessive backlash, a level of precision that separates a hobby RC kit from a genuinely scratch-built combustion vehicle.

It’s the kind of fabrication work that turns up in other DIY vehicle builds featured on his channel and elsewhere in the maker world, similar in spirit to the scratch-engineering seen in projects like the Beast Electric 4X4 off-road build, where custom drivetrain components had to be fitted to a one-off chassis rather than sourced as a matched kit.

The engine only counts once it’s turning the wheels — everything before that is just a very loud paperweight.

Mounting the V4 Power Plant

With the drivetrain roughed in, the episode moves to mounting the tiny nitro V4 into the RC chassis itself. That means securing the engine to its mounts, aligning it precisely with the newly built drive shafts and couplings, and bracing the surrounding chassis so it can handle the vibration a running four-stroke engine produces at speed. Misalignment at this stage would translate directly into drivetrain wear or outright failure once the engine is under load.

This kind of small-scale precision engineering sits in the same DIY tradition as other builder-driven projects in the transport space — the same instinct that drives creators to tackle unusual, hand-built vehicles rather than settle for a factory-standard machine.

Upcoming Phases of Construction

Even with the drivetrain fitted and the engine mounted, the car in this episode still isn’t ready to drive. JohnnyQ90’s series still has to cover the radio electronics needed to control throttle and steering, along with final chassis bracing to keep everything rigid once the V4 is actually firing under load. This installment is squarely the mechanical middle chapter — engine plus drivetrain — before the wiring and control systems turn it into something you can actually point down a driveway.

Given how JohnnyQ90 has structured every build on his channel — engine first, then drivetrain, then electronics, then a full running test — the next upload is almost certainly the one where this little V4 finally gets to prove itself with a radio in hand and four wheels turning under its own power.