A 38mm outside diameter alloy bend, a widely used size for engine bay plumbing. It handles main coolant hoses and radiator routing, high-flow crankcase ventilation, and smaller intake and charge pipework on modest turbo setups. Building these runs in alloy with silicone joins rather than one long moulded hose gives you control over the exact routing and makes future changes far easier, since a single section can be replaced without remaking the whole run. Cut to length, deburr the ends so the silicone is not cut on assembly, and clamp each joint. Bracket the pipework properly, because unsupported alloy sections work their couplers loose over time.