The H23 was an increased-stroke, non-VTEC version of the H22, used
in Japan, North America, and Europe. It shared the same Fiber
Reinforced Metal (FRM) cylinder wall liners with the H22.
H23A DOHC VTEC
In 1998, Honda of Japan produced a rare DOHC VTEC version of the
H23A engine for use in Japan only. It has been factory modified with an
internal oil passage in the H23A block to operate the VTEC solenoid in
the H22A head. Having the same horsepower rating as the H22A engine but
it has a lower redline because it has a longer stroke than H22A. H23A
DOHC VTEC has 87mm x 95mm (bore and stroke)and the H22A DOHC VTEC has
87mm x 90.7mm (bore and stroke). The H23A DOHC VTEC Engine is largest
displacement in the H Series engines with a compression ratio of 10.6:1.