| 摘要 |
A cylinder head ( 10 ) for an internal combustion engine has hydroformed port liners ( 18 ) positioned within selected ports, either exhaust and/or intake ports ( 14, 16 ). The hydroformed port liner ( 18 ) includes an air gap ( 24 ) for an insulation layer within the selected port ( 14, 16 ) between an outer surface ( 19 ) of the hydroformed port liner ( 18 ) and the wall of the port ( 14, 16 ). A cylinder head ( 12 ) with a predetermined port configuration has selected ports ( 14, 16 ) cast with protrusions ( 22 ). The selected ports ( 14,16 ) have a larger diameter than a standard size port diameter for that cylinder head to provide a predetermined port configuration by a preset amount based on the thickness of the hydroformed port liner ( 18 ) and a desired air gap ( 22 ). Protrusions ( 22 ) in the wall of the selected ports ( 14, 16 ) or on the insert sleeves ( 17 ) facilitate formation of the air gap during the hydroforming process.
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