Transparent Cylinder Shows You What You Otto Know About 4 Cycle Engines

When we think of a typical four stroke internal combustion engine, we think of metal. And for any type of longevity or performance, that’s certainly the right choice. But [Integza] wanted to see what happens inside a 4 stroke engine, and it wasn’t enough to see it from a transparent cylinder head. No, he wanted to see it in the cylinder itself. Thanks to advances in material sciences, he got his wish as seen in the video below the break.

While researching possible transparent materials to use as a cylinder on his model engine, he learned about resin polishing. Combining his newly learned resin polishing knowledge with his knowledge of 3D printing, [Integza] printed a new cylinder and polished the resin until it was transparent. The engine ran, but misfired terribly.

The experiment progressed into trying different fuels and learning the differences between them, as well as uncovering a new-to-him mystery: Why was the engine misfiring, and why did the different fuels act so dramatically different? Indeed, more learning and more experimenting is needed. But if you want to see the great sight of watching combustion take place in slo-mo, you have to check out the video below.

3D printing has come a long way in a short time, and may even hold the key to practical scramjets for hypersonic aircraft.

15 thoughts on “Transparent Cylinder Shows You What You Otto Know About 4 Cycle Engines

    1. I read recently that gasoline is naphtha (white gas) with additives. First I wondered why white gas stove fuel costs so much, then wondered if the naphtha + additives is true. What better place to ask?

      1. White gas, at least according to Technology Connections, is basically very primitive/old fashioned gasoline. Not sure it only differs from modern gasoline in additives though.

  1. Ahhhhhh yesssssss the Otto cycle. Commonly reffered to as suck, squeeze, bang, blow! In the late 70’s my dad and older brother spent many an evening assembling a “visible v-8” engine. I was not allowed to touch it because “I was too young”. After the engine was completed Dad and older brother put the 4 “d” cells into the battery pack and turned it on. It ran at about 20 or 30 RPM. Both of them were dissapointed and hatched a plan to make it go faster. We gathered up every battery in the house and wired them in series including 2 6 volt lantern batteries. If I remeber it was in the neighborhood of 36 volts. The power switch was flipped on and the motor ran a glorious 300-400 RPM. The engine then disassembled itself in about 1.4 seconds. They both stood there with their mouths hanging open while my younger brother and myself did the “You blew it up!!!!” victory dance. Ahhh the good old days!

    1. “the Otto cycle. Commonly reffered to as suck, squeeze, bang, blow!”

      Just as pretty much any other combustion engine cycle involving mechanical movement.
      Diesel? Sucks, squeezes, bangs, blows.
      Wankel? Does all four, too. Just more of it.
      Jet engine? Sucks, squeezes, bangs, blows (just all four continuously and at the same time)

      Only one that comes to mind that technically qualifies as a combustion engine (albeit not internal) but does not SSBB would be a rocket engine since it lacks the sucking part.

  2. I can’t dig up a reference on short notice, but in 1973, my middle school science class instructor Steve Sakaske demonstrated a four stroke engine with a transparent (glass?) cylinder to show off combustion. No slo-mo though, which would have been neat. At A.G. Currie Middle School of the Tustin Unified School District, on the off chance that rings a bell for anyone.

  3. I think the air/fuel ratio is not correct for each fuel. 8 stroking is common when there is not enough fuel. When a stroke doesn’t fire there is unburned fuel left hanging around to enrich the next stroke, which will fire. Mixture needs to be changed for each fuel.

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