Last July, we shared with you the video from the Smarter Every Day YouTube channel, where the operation of the carburetor was detailed thanks to a transparent carburetor. In this video, Destin, the engineer who created this channel, 3D printed a carburetor and shot a 4K slow motion video to simply explain how it works. Another YouTuber, TROdesigns, goes further and created a 4-stroke engine equipped with a transparent cylinder, in order to better understand its operation.
The engine in question comes from a 75 Honda XR1977, the cylinder has been replaced by a transparent acrylic version which allows you to see the combustion process taking place. The piston itself is consistent with the original part, but has been deburred and polished to minimize scratches on the plastic cylinder wall. The compression ratio was decreased from 9,5:1 to 8,7:1 to allow it to work with this specific cylinder. The segments are custom machined from Teflon to reduce friction.
Filmed in 4K resolution, this video details the combustion process inside the engine. The intake, compression, combustion and exhaust stages are all clearly visible and the valve gear and piston move together in sequence. The flame is easy to observe in the cylinder, as is the exhaust gas. There's enough detail to see the air/fuel mixture droplets, ignition timing, and rings doing their best to seal the cylinder wall.
For those in a hurry among us, the interesting part starts at 13 min. From the start, there is a lot of detail on the machining of the segments and the careful assembly of the engine. It's also amazing how well it works. Once the engine is warm, scratches and fogging on the acrylic cylinder are minimized and you can easily see what is happening.
As with the clear carburetor, this acrylic block will not last very long and was built for demonstration purposes only. Nevertheless, this video from TROdesigns is relatively exciting to watch!
