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.