[MOC] Radial 6 Fake Engine (large scale OHV)

[JoKo]

There is a big fake engine I designed lately. Inspired by air-cooled airplane engines 

• Radial 6 cylinders
• Over-head valves with pushrods and rockers
• 12 valves / 12 camshaft
• "Accurate" valves timing
• Crankshaft with counterweight
• Displacement: 43cm^3 / 84 stud^3
• Bore & Stroke: 24 x 16mm / 3 x 2 studs
• 1140 pieces

Good points: I'm happy with the valve timing system. I like the "snowflake" shaped gear train. The pushrods and rockers are nice to see working. One single rubber band around the timing module takes care of the valve spring job for the 12 valves altogether.  The counterweight  really helps reducing vibration and a small PF motor can run the engine up to 500 rpm.

Bad points: The 6 cylinder design was dictated by Lego pieces however IRL an odd number of cylinders is the obvious choice for a single row engine. Because of the 4 stroke cycle an odd number of cylinders allows an ever firing order. And my 6 cylinder can not have an even firing order... I's no big deal because there is no actual fire and it is not visible when running "fast". But it is noticeable when it runs slow and upset my perfectionism... 

Instructions: I made building instructions with detailed steps to set the valve timing correctly. Before I publish instructions I'd like to have someone test it. So let me know if you're interested! 

 

 

 

 

 

 

 

 

Videos:

 

 

 

 

Edited July 11, 2025 by JoKo

[Jurss]

Now build a plane around it ;)

Anyway, impressive.

[Davidz90]

Wow, very cool! Impressive that it can reach 500 rpm without falling apart.

[JoKo]

On 7/11/2025 at 3:29 PM, Jurss said:

Now build a plane around it ;)

Anyway, impressive.

Thanks, Even a scaled propeller would be quite huge!

On 7/12/2025 at 11:48 AM, Davidz90 said:

Wow, very cool! Impressive that it can reach 500 rpm without falling apart.

Thank you! It can even reach 1200 rpm with two motors and new batteries! Without falling apppart and the valves are keeping up with the pace

 

[Davidz90]

5 minutes ago, JoKo said:

Thank you! It can even reach 1200 rpm with two motors and new batteries!

Whoa! This is extremely impressive. Probably not healthy for axles, but impressive nevertheless