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[Ali Gibson]

Hi! I’m restoring an older two-stroke motorcycle and need to replace a worn-out venturi nozzle that draws in fuel-air mix. I’m considering having it 3D printed, but I’m unsure which material would best hold up to long-term gasoline exposure and engine heat (ambient temps around 70–90°C, possibly higher during load). Mechanical stress is low, but it needs to be tough—not brittle—and resistant to swelling or degradation over time. Thanks

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[Markus]

So you need a polymer that won’t swell with gasoline, but also one that survives at temperatures that are above most “common plastics” melting points.

What 3D printing technologies are available to you from local service providers? The available technologies will also limit the materials that are available to you. My best guess for a good material would be something like Nylon 12 with an SLS printer.

A more accessible option may be to find a specialized resin for stereolithography (SLA). Unfortunately resins tend to be brand-specific, but there are a number of options for flame-retardant or glass-filled resins that should work.

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[John90]

Depending on how valuable a long service life is to you (whether replacing the part in a year or two is a problem), you could consider going with something cheaper like ABS on a FDM printer. Your expected service temperature is maybe a bit close to the recommended upper service temperature of ABS, so you may risk a shorter service life. If you do try this route, just be sure that the service provider knows how to print with ABS and can avoid the warping and adhesion issues.

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[Rene M.]

Rather use polypropylene if you can – great thermal and chemical resistance, but needs a specialized printer.

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