www.HONDATUNINGmagazine.com
Later-model H-series engines, like our H22A from a '99-to-'01 USDM 'Lude, boast a closed-deck configuration, which increases the motor's appeal to some. In fact in terms of power and compatibility the H22A is considered one of the more coveted engines, making 200 hp at the crank from the factory. It does so with a 90.7mm stroke, 87mm bore, and compression ratio of 10.0:1--which we changed when we opted for the higher domed Japanese Type-S slugs the first time around, upping compression a full point.
In the first installment (Oct./Nov. '02) we noted how thin the stock sleeves were but didn't really get into why they were so thin. The liners are referred to as fiber-reinforced metal (FRM) cylinder sleeves in the Helm's manual, which coincidentally are also used in the 3.2-liter NSX.
Making FRM sleeves goes something like this: First a fiber-based material in the shape of the cylinder sleeve is inserted into the die of the cylinder block. Liquid aluminum is then poured into the die and fuses with the fiber sleeves. Once the block is ready for it, the cylinder walls are machined to the desired bore dimension, leaving only 0.5mm of thickness to the fiber sleeves that cover the cylinder walls.
With the reinforcement the sleeves generate lower friction than traditional iron liners, which translates to improved revolutions, power and reduced wear. In addition the thinner fiber sleeves fortify the block, allowing the distance between adjacent bores to be reduced while maintaining strength and rigidity.
There are drawbacks, however. It can be argued that because they are so thin the sleeves were not designed for too much boost pressure, which limits the potential of the stock engine and poses a challenge for us.
Overboring for more displacement is also out of the question since the sleeves are so lean. Even if you machine-off enough material to avoid breaking through to a water jacket, you still have to deal with the softer untreated metal under the fiber layer. For these reasons it is recommended that H22 sleeves never be bored or honed, always replaced.
Hope that helps.
