This is an axial engine model with 6 cylinders.

Warning:
Due to the high displacement you'll need a huge compressor. Otherwise it may only spin at low speeds. (Example: 300 rpm × 409 ccm × 2 strokes per revolution ≈ 245 liter/min).

Note:
The exploded view of the engine is not quite correct. The O-ring should be inserted into the cylinder head and not directly onto the valves.

Specs:

• Version: 12
• Type: axial 6 - two stroke
• Displacement: 409 ccm (68 ccm per cylinder)

Materials:

• PETG → piston rings
• TPU → head seals
• PLA → all other parts

Parts:
Bearings (inner diameter x outer diameter x width)

• 4x 25x37x7mm
• 4x 15x21x4mm
• 18x 6x17x6mm

O-Rings (inner ø x width)

• 12x 10x2mm (valves)
• 12x 8x2mm (valve caps)

Springs (inner ø x outer ø x height)

• 12x 6.5x10mm (max: ø7.5mm | solid height min: 4mm)

Fittings

• 1x 1/4" pneumatic fitting

Screws (M3 socket screws)

• 6x 6mm (flywheel mass)
• 6x 8mm (exhaust)
• 10x 12mm (crankcase, camshaft)
• 12x 14mm (piston rods)
• 6x 16mm (piston rods)
• 6x 18mm (crankcase cover)
• 1x 20mm (camshaft)
• 1x 25mm (flywheel)
• 30x 30mm (cylinder head, valves, pistons)

Some screws can be a bit shorter/longer. Please check the dimensions using your CAD software. I'd recommend buying a set of these screws.

Inserts

• min. 54x M3 threaded insert (max. height: 6mm)