Building An Engine With An A/C Compressor

Air conditioning compressors aren’t exactly a mainstay of the average hacker’s junk box. Typically, they’re either fitted to a car to do their original job, or they’re on the bench getting refurbished. However, with the right mods, it’s possible to turn one into a functioning internal combustion engine.

The build starts by disassembling the compressor, which contains three double-sided pistons. The housing is drilled with ports to allow gas to flow into and out of the cylinders, as well as to transfer from one side of the piston to the other. Acrylic end plates are fitted to the assembly. One end acts as an intake manifold, delivering air and fuel to the cylinders. The other side acts as the cylinder head, mounting the sparkplugs. Everything is then connected with acrylic tubing and a small square section of acrylic is turned into a carburetor to supply the air-fuel mix. Ignition is handled by coils triggered by the movement of the flywheel.

After an initial failure due to the acrylic manifold cracking, a stronger part is fabricated, and the engine bursts into life. The acrylic end caps give a great view of the combustion process in action. We’d love to see the a dyno graph on how much power and torque the unit puts out, or to see it hooked up to a bicycle or cart.

We’ve seen others attempt their own engine builds, too. If you’ve got an unconventional engine build of your own, be sure to let us know. Video after the break.

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Solenoid Engine Adds Three “Pistons”

The earliest piston engines typically had only one cylinder, and at best, produced horsepower measured in single digits. But once you have a working engine, it’s a relatively short step to adding cylinders and increasing the power output. [Emiel] made a similar upgrade to one of his engines recently, upgrading it from one cylinder to four. But this isn’t an internal combustion engine, it gets its power from electric solenoids.

We featured his single-cylinder build about a month ago, and since then he’s been busy with this impressive upgrade. The new engine features four cylinders arranged in a V4 pattern. Of course, this greatly increases the mechanical complexity. To start, he had to machine a crankshaft to connect all four “pistons” to a shared output shaft. He also had to build a set of cams in order to time the firing of the cylinders properly, so they don’t work against one another.

The build is just as polished and impressive as the last, which is saying a lot. [Emiel] has a quality machine shop and built the entire motor from scratch, including winding the solenoids, machining the connecting rods and shafts, and building a very picturesque wooden base for the entire contraption to sit on. It’s definitely worth checking out.

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Student-Built Rocket Engine Packs A Punch

A group of students at Boston University recently made a successful test of a powerful rocket engine intended for 100km suborbital flights. Known as the Iron Lotus (although made out of mild steel rather than iron), this test allowed them to perfect the timing and perfect their engine design (also posted to Reddit) which they hope will eventually make them the first collegiate group to send a rocket to space.

Unlike solid rocket fuel designs, this engine is powered by liquid fuel which comes with a ton of challenges to overcome. It is a pressure-fed engine design which involves a pressurized unreactive gas forcing the propellants, in this case isopropanol and N2O, into the combustion chamber. The team used this design to produce 2,553 lb*ft of thrust during this test, which seems to be enough to make this a class P rocket motor. For scale, the highest class in use by amateurs is class S. Their test used mild steel rather than stainless to keep the costs down, but they plan to use a more durable material in the final product.

The Boston University Rocket Propulsion Group is an interesting student organization to keep an eye on. By any stretch of the imagination they are well on their way to getting their rocket design to fly into space. Be sure to check out their other projects as well, and if you’re into amateur rocketry in general there are a lot of interesting things you can do even with class A motors.

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Build Your Own Solenoid Engine

A solenoid engine is a curiosity of the electrical world. By all measures, using electricity to rotate something can be done almost any other way with greater efficiency and less hassle. But there’s just something riveting about watching a solenoid engine work. If you want to build one of your own and see for yourself, [Emiel] aka [The Practical Engineer] has a great how-to.

For this build though he used a few tools that some of us may not have on hand, such as a lathe and a drill press. The lathe was used to make the plastic spool to hold the wire, and also to help wind the wire onto the spool itself rather than doing it by hand. He also milled the wood mounts and metal bearings as well, and the quality of the work really shows through in the final product. The final touch is the transistor which controls power flow to the engine.

If you don’t have all of the machine tools [Emiel] used it’s not impossible to find substitute parts if you want to build your own. It’s an impressive display piece, or possibly even functional if you want your build to have a certain steampunk aesthetic (without the steam). You can even add more pistons to your build if you need extra power.

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Rideable Tank Tread: It’s A Monotrack Motorcycle That Begs You To Stop Very Slowly

There will always be those of us who yearn for an iron steed and the wind through your hair. (Or over your helmet, if you value the contents of your skull.) If having fun and turning heads is more important to you than speed or practicality, [Make it Extreme] has just the bike for you. Using mostly scrapyard parts, they built a monotrack motorcycle — no wheels, just a single rubber track.

[Make it Extreme] are definitely not newcomers to building crazy contraptions, and as usual the entire design and build is a series of ingenious hacks complimented by some impressive fabrication skills. The track is simply a car tyre with the sidewalls cut away. It fits over a steel frame that can be adjusted to tension the track over a drive wheel and a series of rollers which are all part of the suspension system.

Power is provided by a 2-stroke 100cc scooter engine, and transmitted to the track through a drive wheel made from an old scuba tank. What puts this build over the top is that all of this is neatly located inside the circumference of the track. Only the seat, handlebars and fuel tank are on the outside of the track. The foot pegs are as far forward as possible, which helps keep your center of gravity when stopping. It’s not nearly as bad as those self-balancing electric monocycles, but planning stops well in advance is advisable.

While it’s by no means the fastest bike out there it definitely looks like a ton of fun. Build plans are available to patrons of [Make it Extreme], but good luck licensing one as your daily driver. If that’s your goal, you might want to consider adding a cover over the track between the seat and handlebars to prevent your khakis from getting caught on your way to the cubicle farm.

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Remanufacturing A Rotary Airplane Engine

If someone tells you they have seen a rotary engine, the chances are that you will immediately think of a Wankel engine, as you might find in some of the more exotic Mazda sports cars. But there is another rotary engine that has a prior claim to the name, and it can be found as the power unit for many early-twentieth-century aircraft. In these rotary engines the cylinders are arranged radially around a stationary crankshaft, and it is the engine itself that rotates. They have the advantage of extreme simplicity, smooth power, and a low parts count, at the expense of total loss lubrication, a relatively large rotating mass, and some difficulty in controlling their power. These rotary engines were largely obsolete by the 1920s, but  recent upsurge of interest in WW1-era aircraft has led to the creation of a small demand for them. New Zealand based Classic Aero Machining Service have stepped in to fill that gap and are remanufacturing the Gnome radial engine, the most numerous design of that era.

For anyone with an interest in internal combustion engines, the Gnome is a fascinating study. It’s a nine-cylinder design that runs a four-stroke Otto cycle, but instead of the two or more valves you might be familiar with from your motor vehicle it has only a single valve. The so-called Monosoupape design uses its valve for both fuel and exhaust, opening it on the inlet stroke as well as the exhaust stroke. The simplicity of a single valve and no carburetor is thus offset by a difficulty in varying its power , so rotary engines would frequently reduce the number of firing cylinders in lieu of throttling back.

The CAMS Gnome is a faithful copy of the original, but with modern metallurgy and the addition of an electronic ignition system. The original castor oil is still used — it seems classic aviation buffs like the smell — but becuase it is notorious for leaving sticky deposits in the engine they are evaluating modern alternatives. They have some technical details on their website, and there’s a good chance you my hear one of their engines one day at an air show near you.

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Three Engines For Every Lada

If you don’t live in a former Eastern Bloc country, odds are that you’ve never seen a Lada driving around your neighborhood. This car is ubiquitous in Russia and its neighboring countries, though, and for good reason: price. Lada gave many people access to affordable transportation who otherwise would have been walking, but this low price means that it’s a great platform for some excellent car hacks as well.

The guys at [Garage 54], an auto shop in Russia, outfitted one of these discount classics with two extra engines. This goes beyond normal bolt-on modifications you typically see to get modest horsepower gains from a daily driver. The crew had to weld a frame extending out of the front of the car to hold all the extra weight, plus fabricate all the parts needed to get the crankshafts on each engine to connect to each other. After that, it was the “simple” job of tuning the engines to all behave with one another.

This video is really worth watching, as the car was also upgraded with a dually setup on the back with studded tires for extra grip on their ice track. Odds are pretty good that this car isn’t street legal so this is likely the only place they’ll be able to drive it. Other things can be built out of Ladas as well, like lawn mowers for example.

Thanks to [g_alan_e] for the tip!

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