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All-Plastic Engine Project Uses 3D Printed Composite Fuel Intake Runner

Arevo Labs fabricates Polimotor 2 engine component using Solvay’s reinforced PEEK material

ALPHARETTA, Ga.—Polimotor 2, a technical project led by automotive innovator Matti Holtzberg that aims to design and manufacture a next-generation, all-plastic engine for competitive racing in 2016, will feature a 3D-printed fuel intake runner fabricated from a reinforced grade of Solvay’s KetaSpire® polyetheretherketone (PEEK). Arevo Labs, a Silicon Valley-based developer of additive manufacturing technology for composite parts, produced the part using its innovative Reinforced Filament Fusion technology.

“The intake runners in the original Polimotor engine were made from aluminum, but today the automotive industry relies almost entirely on injection-molded nylon,” said Holtzberg, president of West Palm Beach, Fla.-based Composite Castings, in a press release. “That choice of materials is changing now, too, as automakers seek innovative new alternatives like Solvay’s PEEK that can withstand rising under-the-hood temperatures caused by the growing use of turbochargers and engine downsizing, both of which are resulting in higher specific power outputs.”

Intake runners appear in both racing and production-scale cars, and are typically integrated with an engine’s plenum, which is the pressurized chamber that uniformly distributes air flow between an engine’s air inlet and its cylinders. A transition piece between the cylinder head and the plenum chamber, the intake injects fuel into the air stream just as it enters the engine, and its performance has a direct influence on the engine’s horsepower.

Replacement of the original aluminum runner with PEEK reportedly reduced the part’s weight by 50 percent. The specific material chosen for Polimotor 2 was a custom-formulated grade of KetaSpire® KT-820 PEEK, reinforced by a 10 percent carbon fiber loading. KetaSpire PEEK offers excellent chemical resistance to automotive fuels and reliable mechanical performance at continuous-use temperatures up to 240°C (464°F), according to Solvay. These qualities made it a highly suitable candidate for Polimotor 2’s fuel intake runner, which encounters temperatures reaching 150°C (302°F) near the pistons in the intake port.

Like conventional filament fusion 3D printing processes, Arevo’s technology bonds polymer filaments on top of or alongside each other in successive stages to ultimately form complex shapes. Thus, it can quickly convert digital designs into functional parts without the time or cost required to first build a molding tool and prototype. However, the company’s Reinforced Filament Fusion platform offers the unique ability to print with reinforced PEEK polymers. When combined with Arevo’s process control software, the platform can help optimize the mechanical properties of printed parts.

“The convergence of 3D printing with Solvay’s PEEK polymer technology in this application underscores how truly cutting-edge the Polimotor 2 project is,” said Brian Baleno, global automotive business manager for Solvay Specialty Polymers, in the release. “Neither of these technologies existed in the ‘80s when Matti Holtzberg developed the first Polimotor engine; and now, with this runner, we see one of the very first carbon fiber-filled PEEK parts to be fabricated with the additive manufacturing process. That signals a whole new range of possibilities for automakers seeking lighter, but high-performing alternatives to metal.”

Solvay, a global supplier of high-performance polymers, is the principal material sponsor for Polimotor 2. For more on the Polimotor 2, see Are You Ready for an All-Plastic Automotive Engine?