What is up engine heads! Today we are going to be taking a look at a real milestone for engines. A set of 3d printed pistons that recently passed a pretty demanding endurance test in a very serious Porsche engine.

Watch Mahle's original video:    • MAHLE 3D-printed pistons for the PORS...  

Many people still think that 3D printing is years away from industrial use. But Porsche begs to differ and decided to demonstrate the industrial future of 3d printed automotive parts. Porsche has been 3d printing some stuff for a while now, but it's been stuff like parts of your seat. A piston has to survive extremely high combustion pressures and temperatures all while going up and down thousands of times per minute and rapidly changing direction as it reaches the top and bottom of it's stroke. This why 3d printed seat parts are cute, but 3d printed pistons are an entirely different ball game.
So Porsche gathered the cream of German engineering seriousness. Big names like Mahle, Trumpf and Carl Zeiss. Together with Porsche they tackled the challenge of designing, manufacturing and testing a set of 3d printed pistons for the fastest 911, the GT2 RS. When it comes to Porsche it doesn't get much better and much faster than this car. So if a set of 3d printed pistons can survive in it's engine, it can likely survive pretty much everywhere else
The pistons underwent an endurance test which included 135 hours under full engine load and this is no small feat when you remember that the engine in the GT2 RS is a 3.8 liter twin turbo flat six whose full load produces 700 metric horsepower at 7000 rpm with the help of 1.55 bar of boost. (22psi)

Porsche claims that the pistons passed the test with flying colors and although they are not production ready yet and you likely won't seem them in large scale production Porsche cars just yet, the technology is here to stay and the test is proof that 3d printing has a very promising future in engine internals.

3d printing technology allows the pistons to have material only in areas which are subject to high forces and stresses which means the pistons can be made ligther. These pistons managed to get 30 additional horsepower out of an already very high strung engine. A very nice feature they have is an integrated oil cooling channel passing right underneath the piston crown. This is something that is simply impossible to make on a forged piston. And because the piston runs 20 degrees cooler thanks to this duct you also reduce the chance of knock which means you can further advance ignition timing. This coupled with lighter pistons also means you can rev the engine higher and voila, 30 more horsepower.

The pistons are created in a high-precision Trumpf TruPrint 5000 (I said 3000 and displayed 3000 machine footage in the video - this is a mistake) laser 3D printer that basically builds the parts 0.02 to 0.1 millimetre layer at a time by fusing a fine metal powder with lasers. The material used for the pistons is a proprietary alloy called M1174+ this an alloy developed and provided by Mahle.

Before chucking these things into an engine Porsche really wanted to make sure they are absolutely up to spec so they got Carl Zeiss to to test and measure the pistons with light microscope inspection, electron microscope scanning, X-ray microscope and 3D scanning. I honestly don't know what's the difference between all of these technologies, but it's pretty obvious they really wanted to make sure that the pistons don't fail.

So we know that these pistons are 10% lighter and they have a nice oil cooling duct that helps them run 20 degrees cooler. But what about strength? Porsche doesn't give us any data here, they just say that they are "extremely strong" and " comparable to those of cast materials for production pistons". So this likely means that when it comes to things tensile strength and ductility, these printed pistons are likely weaker than a set of forged pistons, but that actually only matters when knock occurs. These pistons are likely more brittle than a set of forged ones, and would likely crack when exposed to knock sooner than a set of forged pistons. But that doesn't matter if knock never happens. The GT2 RS isn't running DIY mega-squirt, it's running state of the art engine management that makes sure knock doesn't actually happen.

It might seem contradictory but new technologies will allow us to squeeze out even more potential from the ancient engines we still love and tune today.

A special thank you to my patrons:
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William

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Green screen horses:    • Video  
3D printed wind turbine video:    • Prototype: 3D printing the first 10m ...  

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