Make:

Great video! And thank you for the safety glass reminder!

At the end of the video, you say that the engine could run continuously if set up to do so. Is there any videos of it running like this? I've been wondering how the PVC would stand up to the heat stress of continuous use. I'd love to see it, especially if the crank shaft was hooked up to something else too.

I think these videos have gotten a whole lot better in the last couple of episodes, my only complaint is that sometimes it was hard to hear Kip, specifically in the garage/workshop area.

This is just crazy (and VERY VERY dangerous!). An "engine" like this wil never work, it is not able to stand the forces/stress involved. This is essentially a PVC-pipebomb with a crankshaft.

Posted by: JP on March 28, 2008 at 9:31 AM

Kip, I really enjoyed this video. It was great to see a few of the snags along the way.

John - of course it's dangerous, it would make so much money on Metacafe if it wasn't. Also the reason it's called the explosion engine, to get kids watching.
You could get a better working engine just using the air compressor but of course then it wouldn't be dangerous so wouldn't be as popular.
That's why you'll never see Kipkay doing Origami projects, if he did, the paper would have to be on fire.

Posted by: KipKay on March 28, 2008 at 11:57 AM

@John - I used a second burst of butane. I guess 'danger' is in the eye of the beholder. Of course it will not be a real engine, it's an 'engi-cational' project to show what happens inside an engine. The author, David Simpson, designed and built this to explain to his Civil Air Patrol cadets what happens inside an internal combustion engine.

Pretty neat experiment!

Just a little math work...You'd get 83.3 explosions every second @ 5000rpm if you had a 2-cycle single-cylinder engine (like a chainsaw or goped engine), or a 4-cycle twin cylinder (like most harley davidsons use).

The v8 4-cycle motor in my mustang explodes around 333 times every second at 5000rpm. Because it's a 4-stroke, each cylinder only generates power every other crank revolution.

The twin rotor wankel motor in my rx-7 goes boom around 167 times/sec @ 5000rpm because it generates one power cycle per "cylinder", per crankshaft revolution.

Here's a good site that shows lots of engine animations. http://www.keveney.com/Engines.html

I think this project was sick! I feel like it wouldn't be too difficult to make the engine spark every two strokes, but I'm not sure how hot the engine would actually get, and melting PVC isn't so friendly. I'm glad you did this project because I have neither the time nor the resources to try it and I really wanted to see this thing in action. Absolutely awesome.

Posted by: KipKay on March 28, 2008 at 12:35 PM

@Russ - Thanks for the great information. I just did a qucik calculation in my head to come up with the 'dozens' per second. That's what I did, 5000rpm divided by 60. Thanks

Posted by: KipKay on March 28, 2008 at 1:06 PM

@Selfsilent - "origami". LOL! Yea that's what the MAKE crowd wants. No, the reason I won't do origami is because I could get a paper cut and that would hurt.

Posted by: Pocket-Sized on March 28, 2008 at 3:02 PM

Very well done KipKay,
To begin with when you first joined Make I was very cynical.

But what can I say... You've definitely improved. You give credit where credit is due, you are fun to watch, and very informative.

Keep it up =)

The failures were hillarious. Good to know everyone fails sometimes, not just me :)

not bad, but i really have to condem the use of pvc pipe for anything involving high pressure, fire, or explosions.

1) burning pvc fumes = bad
2) broken pvc plastic = shrapnel

abs plastic does not, to my knowledge, release anything nearly so harmful when it burns (which happens at a much much higher temp), nor is it nearly so brittle, making it less prone to catastrophic failure.

Heya! Way more fun to watch, great video! Definitely going in the right direction. Keep it up!

Kipkay,
Please don't denigrate origami! There have been lots of origami stories on the Make blog, so I think makers accept it as a form of making and probably wouldn't complain if you do decided to do an origami video. Let me know if you want help on such a project! We'll make sure to wear safety equipment to protect you from paper cuts.

BTW, I did like that you showed all the setbacks and modifications they required. The safety glasses cracked me up, too.

Really liked the video.

Even the third try was producing shrapnel. How about a Make segment on safety shields (and liability coverage)?

Internal combustion engines rely on the expansion of heated air, not the shock wave of an explosion to operate. Slow burning of the fuel spray is one of the reasons that low speed Diesel engines produce a higher torque curve than standard Otto cycle (car, lawnmower etc.) engines.

Posted by: KipKay on March 29, 2008 at 8:42 AM

@ThermoGeek - Yea the 'shrapnel' was actually some plastic shavings from when I drilled the hole in the cylinder to secure it with the lag screw. If you watch closely you can see some fire that exited the exhaust port. You are correct that an internal combustion engine relies on the combustion of the gas/fuel and air mixture that forces the piston down. Thanks!

A good video, I liked showing the setbacks (you don't have to show all of them, just a few to help us remember that projects rarely work perfectly the first time around) And the safety glasses reminder was a good thought. Congrats.

i dont like kip kay. what happened to bre pettis

Wow... Compare this dangerous macho crap with one of the inspired Bre videos like "Build a Single Speed Bike"... What a change. Make Video has dropped to the bottom of my feed list...

Subscribe today, save 42% and get web access to MAKE free. MAKE Digital Edition is available only to subscribers.

$34.95 / 1 year
(4 Quarterly Issues)

Subscribe now