Additive manufacturing has come a long way in a short time, and the parts you can turn out with some high-end 3D-printers rival machined metal in terms of durability. But consumer-grade technology generally lags the good stuff, so there’s no way you can 3D-print internal combustion engine parts on a run of the mill printer yet, right?
As it turns out, you can at least 3D-print connecting rods, if both the engine and your expectations are scaled appropriately. [JohnnyQ90] loves his miniature nitro engines, which we’ve seen him use to power both a rotary tool and a hand drill before. So taking apart a perfectly good engine and replacing the aluminum connecting rod with a PETG print was a little surprising. The design process was dead easy with such a simple part, and the print seemed like a reasonable facsimile of the original when laid side-by-side. But there were obvious differences, like the press-fit bronze bearings and oil ports in the crank and wrist ends of the original part, not to mention the even thickness along the plastic part instead of the relief along the shaft in the prototype.
Nonetheless, the rod was fitted into an engine with a clear plastic cover that lets us observe the spinning bits right up to the inevitable moment of failure, which you can see in the video below. To us it looks like failing to neck down the shaft of the rod was probably not a great idea, but the main failure mode was the bearings, or lack thereof. Still, we were surprised how long the part lasted, and we can’t help but wonder how a composite connecting rod would perform.
Still in the mood to see how plastic performs in two-stroke engines? Break out the JB Weld.
The piston engine has been the king of the transportation industry for well over a century now. It has been manufactured so much that it has become a sort of general-purpose machine that can be used to do quite a bit more than merely move people and cargo from one point to another. Running generators, hydraulic systems, pumps, and heavy machinery are but a few examples of that.
Scale production of this technology also had the effect of driving prices for these engines down, and now virtually everyone in the developed world has cheap and easy access to them. In the transportation world, at least, it looks like its reign might finally be coming to a slow, drawn-out conclusion as electric cars capture more and more market share.
Electric motors aren’t the first technology to try to topple the piston engine from its apex position on top of our modern transportation industry, though. In the 1960s another technology, the gas turbine engine, tried to replace it — and failed.
[Makerj101]’s video series takes us through his entire conversion process. Despite the outward similarity between compressors and engines, there are enough crucial differences to make the conversion challenging. A scheme for controlling intake and exhaust had to be implemented, the crankcase needed to be sealed, and a cylinder head with a spark plug needed to be fabricated. All of these steps would have been trivial in a machine shop with mill and lathe, but [Makerj101] chose the hard way. An old CPU heat sink serves as a cylinder head, copper wire forms a head gasket and spacer to decrease the compression ratio, and the old motor rotor serves as a flywheel. JB Weld is slathered everywhere, and to good effect as the test run in the video below shows.
Think you recognize [Makerj101]? You probably do, since we featured his previous machine shop-less engine build. This guy sure gets his money’s worth out of a tube of JB Weld.
Electric cars are all the rage lately, but let’s not forget about the old standby – internal combustion. The modern internal combustion engine is a marvel of engineering. Today’s engines and surrounding systems have better power, greater fuel economy, and lower emissions than anything that has come before. Centuries’ worth of engineering hours have gone into improving every aspect of the engine – with one notable exception. No automotive manufacturer has been able to eliminate the engine’s camshaft in a piston powered-production vehicle. The irony here is that camless engines are relatively easy to build. The average hacker could modify a small four-stroke engine for camless operation in their workshop. While it wouldn’t be a practical device, it would be a great test bed for experimentation and learning.
Suck, Squeeze, Bang, Blow
A multi-cylinder gasoline engine is a complex dance. Hundreds of parts must move in synchronicity. Valves open and close, injectors mist fuel, spark plugs fire, and pistons move up and down. All follow the four-stroke “Intake, Compression, Combustion, Exhaust” Otto cycle. The camshaft controls much of this by opening and closing the engine’s spring-loaded intake and exhaust valves. Lobes on the shaft press on tappets which then move the valve stems and the valves themselves. The camshaft itself is driven at half the speed of the crankshaft through timing gears, chains, or a belt. Some valve trains are relatively simple – such as overhead cam engines. Others, such as the cam-in-block design, are more complex, with pushrods, rockers, and other parts required to translate the movement of the cam lobe to movement at the valve.
Exactly when, and how fast a valve opens is determined by the profile of the cam lobe. Auto racing and performance enthusiasts often change camshafts to those with more aggressive profiles and different timing offsets depending on the engine’s requirements. Everything comes at a cost though. A camshaft machined for maximum power generally won’t idle well and will make the engine harder to start. Too aggressive a lobe profile can lead to valve float, where the valves never fully seat at high RPM.
Myriad Solutions
Engine manufacturers have spent years working around the limitations of the camshaft. The results are myriad proprietary solutions. Honda has VTEC, short for Variable Valve Timing and Lift Electronic Control. Toyota has VVT-i. BMW has VANOS, Ford has VCT. All these systems provide ways to adjust the valve action to some degree. VANOS works by allowing the camshaft to slightly rotate a few degrees relative to its normal timing, similar to moving a tooth or two on the timing chain. While these systems do work, they tend to be mechanically complex, and expensive to repair.
The simple solution would be to go with a camless engine. This would mean eliminating the camshaft, timing belt, and most of the associated hardware. Solenoids or hydraulic actuators open and close the valves in an infinitely variable number of ways. Valves can even be held open indefinitely, effectively shutting down a cylinder when max power isn’t necessary.
So why aren’t we all driving camless engines? There are a few reasons. The advantages of camless engines to camshaft engines are analogous to the advantages of electronic fuel injection (EFI) vs carburetors. At the core, a fuel injector is a solenoid controlled valve. The fuel pump provides constant pressure. The engine control unit (ECU) fires the injectors at just the right time to inject fuel into the cylinders.The computer also leaves the valves open long enough so that the right amount of fuel is injected for the current throttle position. Electronically this is very similar to what would be required for a camless engine. So what gives?
Toyota’s celebrated 22R-E, an early EFI engine
Hackers in their 30’s and beyond will remember that until the late 1970’s and early 1980’s, the carburetor was king. Companies had been experimenting with EFI since the 1950’s. The system didn’t become mainstream until the stiff pollution laws of the 70’s came into effect. Making a clean, fuel-efficient carbureted engine was possible, but there were so many mechanical and electronic actuators required that the EFI was a better alternative. So the laws of the 70’s effectively regulated carburetors out of existence. We’re looking at much the same thing with camless engines. What’s missing are the regulations to force the issue.
All the big manufacturers have experimented with the camless concept. The best effort to date has been from Freevalve, a subsidiary of Koenigsegg. They have a prototype engine running in a Saab. LaunchPoint Technologies have uploaded videos showing some impressive actuator designs LaunchPoint is working with voice coils, the same technology which moves the heads in your hard drive.
None of this means that you can’t have a camless engine now – companies like Wärtsilä and Man have engines commercially available. However, these are giant diesel engines used to drive large ships or generate power. Not exactly what you’d want to put in a your subcompact car! For the hacker set, the best way to get your hands on a camless engine today is to hack one yourself.
Ladies and gentlemen, start hack your engines!
Simple, single-cylinder camless engines are relatively easy to build. Start with a four stroke overhead valve engine from a snowblower, scooter, or the like. Make sure the engine is a non-interference model. This means that it is physically impossible for the valves to crash into the pistons. Add a power source and some solenoids. From there it’s just a matter of creating a control system. Examples are all over the internet. [Sukhjit Singh Banga] built this engine as part of a college project. The control system is a mechanical wheel with electric contacts, similar to a distributor cap and rotor system. [bbaldwin1987’s] Camless Engine Capstone project at West Virginia University uses a microcontroller to operate the solenoids. Note that this project uses two solenoids – one to open and one to close the valve. The engine doesn’t need to rely on a spring for closure. [Brian Miller] also built a camless engine for college, in this case Brigham Young University Idaho Camless Engine. [Brian’s] engine uses hall effect sensors on the original camshaft to fire the solenoids. This route is an excellent stepping stone before making the jump to full electronic control.
It wouldn’t take much work to expand these projects to a multi-cylinder engine. All we’re waiting for is the right hacker to take up the challenge!
The sheer beauty of this build is blinding. We enjoy keeping a minimalistic household — not quite on the level of [Joe MacMillan] but getting there — yet this would be the thing we choose as decoration. It’s a hand-built 2-stroke Engine designed specifically to make the combustion process visible rather than locking it away inside of a block of metal.
If you have a nagging feeling you’ve seen this before it’s because the amazing craftsmanship is unforgettable. A couple years back we looked at the 4-stroke engine also built by [Huib Visser]. This new offering does away with the belt, leaving a build that is almost entirely glass and metal polished to a high sheen. The glass cylinder contains the combustion, pushing the graphite piston to drive the fly-wheel. A passing magnet triggers the spark plug to ignite the white-gas fuel, all of which is well-illustrated in the video after the break.
This is not for sale, which doesn’t surprise us. How hard would it be to part with something of such beauty especially knowing you created that beauty? But don’t worry, you can definitely build your own. Just make sure to set the bar lower for your first half dozen tries. We’ve even seen engine builds using hardware store parts.
We had no idea that what’s needed to convert an internal combustion engine to steam power is actually rather trivial. [David Nash] shows us how it’s done by performing the alterations on the engine of a string trimmer. These are the tools used to cut down vegetation around obstacles in your yard. The source of the engine doesn’t really matter as long as it’s a 2-cycle motor.
This engine had one spark plug which is threaded into the top of the block. [David] removed this and attached his replacement hardware. For now he’s using compressed air for development, but will connected the final version to a boiler.
There are only a couple of important parts between the engine and the boiler. There’s an in-line oil reservoir to help combat the corrosive nature of the steam. There is also a check valve. In the video after the break [David] shows the hunk of a ball-point pen that he uses to actuate the check valve. It’s really just a spacer that the piston pushes up to open the valve. This will be replaced with a metal rod in the final version.
A multi-cylinder gasoline engine is a complex dance. Hundreds of parts must move in synchronicity. Valves open and close, injectors mist fuel, spark plugs fire, and pistons move up and down. All follow the four-stroke “Intake, Compression, Combustion, Exhaust” 
Engine manufacturers have spent years working around the limitations of the camshaft. The results are myriad proprietary solutions. Honda has VTEC, short for Variable Valve Timing and Lift Electronic Control. Toyota has VVT-i. BMW has VANOS, Ford has VCT. All these systems provide ways to adjust the valve action to some degree. VANOS works by allowing the camshaft to slightly rotate a few degrees relative to its normal timing, similar to moving a tooth or two on the timing chain. While these systems do work, they tend to be mechanically complex, and expensive to repair.
Simple, single-cylinder camless engines are relatively easy to build. Start with a four stroke overhead valve engine from a snowblower, scooter, or the like. Make sure the engine is a non-interference model. This means that it is physically impossible for the valves to crash into the pistons. Add a power source and some solenoids. From there it’s just a matter of creating a control system. Examples are all over the internet. [Sukhjit Singh Banga] built 
