# A 3D-printed engine gets five valves per side

Alexander's Laboratory squeezed ten valves into a small engine's cylinder head, using large wood screws as the valves and one camshaft driving all of them.

- Category: Hardware (mod)
- Made by: [Alexander's Laboratory](https://www.youtube.com/watch?v=njTlfWwiXJ4) on YouTube
- Original: https://www.youtube.com/watch?v=njTlfWwiXJ4
- On Afterware: https://afterware.xyz/p/a-3d-printed-engine-gets-five-valves-per-side

## Can I build this?

- Difficulty: Expert
- AI-buildability: 2/5 (The work is mostly CNC machining, lathe work, engine assembly and tuning, with AI only helping a little with CAD and design calculations.)
- Time: A month or more
- Cost: $300–800
- Parts: worm gear
- Tools: CNC mill, 3D printer, lathe, wood screws, engine tuning equipment

Estimates based on the original write-up. How the AI-buildability score works: https://afterware.xyz/ai-buildability

## Build sheet

- Base: 3D-printed ICE
- Head: CNC alu + nylon hybrid
- Valves: 10 per cylinder (wood screws)
- Camshaft: Original, with 5-valve adapter

## Starter prompt

```
Based on "A 3D-printed engine gets five valves per side" on Afterware: https://afterware.xyz/p/a-3d-printed-engine-gets-five-valves-per-side

I have a small 3D-printed single-cylinder four-stroke engine with a four-valve head. Help me design a new cylinder head with five intake and five exhaust valves that is driven by the original camshaft through a rocker or pushrod adapter. Start with the valve spacing and the timing math for the adapter.
```

## Story

Most engines make do with the fewest valves they can get away with. This one runs ten. The maker swapped the stock four-valve head on a largely 3D-printed engine for a new one with five intake and five exhaust valves per cylinder, a layout inspired by the 20-valve Yamaha FX750.

The valves are large wood screws, chosen after checking they could handle combustion heat. Ten of them barely fit into a head made from a CNC-machined aluminium and nylon-printed hybrid. The original camshaft stayed in place, driven through an adapter that actuates all five valves on each side at once. After some troubleshooting and tuning, the engine runs well.

Worth stealing: the valve-count trick is a cheap way to test a head design, since screws and printed parts cost little. The video doesn't give power or efficiency numbers against the four-valve head, so the performance question is still open.

## Resources

- [Build video](https://www.youtube.com/watch?v=njTlfWwiXJ4)

Tags: internal combustion, 3d-printed, cylinder head, valve train, cnc aluminium, engine build

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