Cylinder Technology
If you own an older B21A1-equipped Prelude, NA2 NSX, AP1 S2000, or almost anything with an H22A/H23A engine in it, you may have noticed that, as mileage and wear and tear increases, so does oil consumption. Each vehicle's engine above shares one thing in common: they all have FRM-lined (Fiber Reinforced Metal) cylinder blocks. FRM is a thin but strong lining material that consists of a fiber matrix, aluminum alloy, and aluminum oxide. It's inserted into the cylinder casting when molded, cooled, and bored out, and then left as a thin lining material for the piston rings to brush up against. The results are tough, resilient cylinders that can put up with their fair share of abuse. But FRM linings aren't all perfect. Because of the material's strength and composition, it's easy for oil to pass by the piston rings, up into the combustion chamber where it has nothing left to do but burn and cause you headaches. Besides the smoking stench of billowing oil from the tailpipe, the process can also cause premature piston ring wear--never a good thing when performance is a concern.