This is a 35% scale model of a Subaru engine, the EJ20 flat-four, which is not only 3D printable but also fully functional. 

Mechanical engineer Eric Harrell — alias ERICTHEPOOLBOY on Thingiverse — has a passion for automotive 3D printing projects, most famously a working 3D printed replica of a Toyota 4 Cylinder Engine 22RE.

His new replica of a Subaru EJ20 flat-four engine is just as impressive: “It’s fully functional as in all parts move as intended in the real thing.”

But he’s quick to point out that you ”do not confuse it with a real engine, as this is not.”

If you’d attempted to build Harrell’s Toyota engine replica previously, be aware that his Subaru engine design is even more of a challenge.

Ready to Build Your Own Subaru Engine?

Harrell has some words of advice to anyone interested in building their own:

“It is best to print or familiarize yourself with my previous models if you choose to print this one. The scale is once again 35% of the original which seems to be a good size for printing and finding fasteners that work and look right. The tolerances are a little tighter and depending on your printer the crankshaft might take some tweaking to get it right so that there is not interference while rotating.”

In order to design the motor, Harrell used CAD program SolidWorks, but he won’t share these files publicly. Instead, we have to make do with the 3D printable files posted to Thingiverse.

Harrell used his own Prusa i3 RepRap 3D printer to fabricate these parts, meaning you can easily print the engine model on any regular FDM 3D printer. He also adds that he 3D printed everything at 0.2 mm resolution with a 20-40% infill.

While you get printing and building, Harrell is embarking on his next project. “Next I would like to do the AWD transmission for this engine or a LS1. If anybody can help with providing an engine to model from, it would be greatly appreciated.”