dudeface

might get more views w/o the ai in the thumbnail! 

Quote from: Dave OttoSo I manually changed the URL in my first post and now it shows the video thumbnail, so that seemed to have worked. I guess there isn't a way to change it in the our YouTube channel?

Dave

Nope, the only way would be to re-upload it in a horizontal format.

The video will appear as a normal video if you replace "shorts/" in the URL with "watch?v=".
Any vertical video under 3:00 is automatically a short.

Hello engine1ear! DF's Lego Stuff n Stuff here. Delton is insane...

If the cranks for the side rods are set 180 degrees from each other, that won't work. They have to be 90 (the way locomotive side rods are set).
(Bentley once made OHC engines using the same system to drive the camshaft, so it certainly works.)

I suppose I should show you my V10 that I changed my profile picture to.
https://www.youtube.com/watch?v=cfFdaZOYnwc
More can be seen on my YT channel.

This one is a square 4 of the "poppet butterfly" type: butterfly (tilting) pistons and a single overhead poppet valve for each cylinder, actuated by an overhead cam. Instead of a manifold the design is simplified by using the cam cover as the manifold. This thing ended up sounding like an actual Detroit Diesel or something. 
https://www.youtube.com/watch?v=f7JU2lAk2Do

Fun 

Here's something similar to a U configuration but with a third crankshaft. I'm calling it an E configuration. This is an "E3" with 2x2 stud pistons. My 2x2s are always finicky but I'd like to try a 4x4 E6 (or maybe an E9??  )
https://www.youtube.com/watch?v=ZGZB1l51mU0
And on the subject of weird LEGO vacuum engines, how about a 5x5 piston with rotary valves! This also has a counterweighted crank and can run much faster than this but the vacuum filter was super clogged in this video.
https://www.youtube.com/watch?v=NIo2aog3yk8

My favorite combination of builds yet, my double acting engine and a twin stick 8 speed transmission.
https://m.youtube.com/watch?v=IaLAPxDNY-4&t=71s

Here's the full 13 minute video if anyone feels like watching it, but basically it's a sequential 4 speed going into a close ratio 2 speed or splitter.
https://m.youtube.com/watch?v=VPugLC_BhnQ&t=69s

Hello!  Welcome!

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A while ago I said I probably wouldn't build another flat 4. Well, here I am with another flat 4! My original idea (a really long time ago) was to build an oscillating v8. That didn't happen, but I ended up building this very smooth running, single acting oscillating flat 4. The main framework of the engine doubles as a manifold, and the crankshaft also passes through it. Because half the engine is effectively turned upside down, one bank "exhausts" out the top and the other out the bottom, as you can see in the attached photos. Here's a video of it running: https://m.youtube.com/shorts/YA9s5NuIPjE

That seems to run pretty good!

I found a broken garden tool handle that fits nicely inside some PVC pipe I have, so naturally it had to become an engine. I came up with this simple design. The wood handle will be the piston and valve, the latter having offset ports in it for intake and exhaust and being perpendicular to the cylinder, pivoting back and forth via a connecting rod. Here's a couple quick sketches and photos.
Photo A: the piston is all that's currently anywhere close to being done.
Photo B: I'll make the connecting rods from this old hacksaw blade.
Photo C: The fit of the piston inside the PVC pipe.
The crankshaft will be bent out of some thick wire.