I happened upon this video and thought that you’d all like to see this one.
Yosemite
OK, I admire the machine work. That crankshaft alone was a peice of machineist’s art. But was it really running, or what he just blowing air through it? I saw no ignition system to speak of.
It must be air operated. I couldn’t see anything on the heads that resemble glow plugs such as used in RC airplanes.
That’s a stunningly brilliant exercise in machining though. His wife must have left him decades ago and he never even noticed… 
Well, here’s a tiny V8 that actually runs on fuel… https://youtube.com/watch?v=B9zt3SF_Flc
If that isn’t enough, here’s a guy that made a 1/3-scale running replica of a Ford 302. It looks to be complete with a pressurized oiling system, tiny oil filter, tiny fuel pump, liquid cooling, etc. https://youtube.com/watch?v=Y0HJjvyLj9E
Wonder what I would do if I had that much free time… probably be lazy.
The first one of these I ever saw was in the February 1994 issue of Popular Mechanics. The guy had not only made a complete, functional, 1/4 scale V8, he also made a blower, various carb setups, a complete drivetrain with differential, a complete T-bucket hot rod, and an AC Cobra chassis. The T-bucket has a dropped tube front axle, the AC Cobra has a fully operating independent suspension. Fully functional disc brakes are on both vehicles. I’m looking at the article as I write… I was so impressed I kept it.
Since that time I’ve discovered that there have been a number of engines made like this, but this was the most impressive I’ve ever seen.
Maybe a bit bigger, but how about a motorcycle with a Ferrari V8:
How often does he change that timing belt? I think the interval when the engine is in a Ferrari body is 30,000 miles.
At least he doesn’t have to drop the engine, like they do for the 308!
The V12 couldn’t possibly run even with fuel and spark systems added. The cams are turning at crankshaft speed (oops).
All that pretty workmanship on that motorcycle and he puts a scoop on the side with all the charm of a trash can. Something curvaceous is called for.
I agree; that scoop comes across as a cheap tack on at the last minute.
Wonder if anyone has the cajones to wick the throttle open quickly…
I thought about it on my way home from work last night, and remembered that as he was putting the pistons in, I thought “where are the piston rings?” I watched it again, and sure enough, no piston rings, so it’s definately running on air. Doesn’t take away from the impressive work in the least.
Here’s a video of a minniature supercharged hemi V8 that runs.
From the “You ain’t seen nothin’ yet folks!” department:
A museum for minniature engines, many of which run:
I thought about it on my way home from work last night, and remembered that as he was putting the pistons in, I thought "where are the piston rings?" I watched it again, and sure enough, no piston rings, so it's definately running on air.
Actually, a lot of micro engines use ringless pistons. You ever see rings on the pistons of the old Cox .049 cubic inch model airplane engines?
When your fuel is around 20% castor oil, the oil film between the piston and cylinder wall is your piston ring.
Even some .60 cubic inch model airplane engines are ringless.
I think what this guy built is actually a V-12 single acting steam engine. He could hook it up to a little boiler and legitimately claim it’s an engine. He could even switch the steam inlet from the intake manifold to the exhaust manifold and run it backwards.
I’ve got a metal lathe and have turned out a few small parts now and then but nothing on the scale of what those guys are doing. The stuff I’ve done has been a bit maddening at times and I can’t even comprehend the patience and focus needed to do what they did much less the time involved.
Those aren’t engines as much as they’re works of fine art. Renoir and Monet would throw in the towel if exposed to those works… 
I too thought that it was a real work of art for these guys to build these and I’m glad that some of you posted others in that same category.
I knew from my childhood that the old cox motors had no rings and noticed that there was no ignition to speak of, but I did think it was cool. I would have pulled my hair out trying to get all that right.
Thank you all for your comments.
Yosemite
Along those lines, how about model jet turbines and the ultimate RC aircraft.
There’s no way I would want the controls in my hands as I’d be a nervous wreck thinking about how much time and money was put into that thing. In my hands a disaster would be looming…
The aircraft would have looked a bit better in dark green and built as the earlier tall tail variant instead of the G model IMO, but it’s a masterpiece no matter what.
The A.M.A. (Academy of Model Aeronautics) requires a special waiver or endorsement in order to be allowed to fly a turbine powered model airplane. Essentially you have to get people to vouch for the fact that you are an advanced flyer with experience flying high speed model airplanes.