High Quality Content by WIKIPEDIA articles! The Mazda K-series automobile engine is a short stroke, 60° V6 24-valve with belt-driven DOHC and aluminum-alloy cylinder heads and block. Their displacements range from a tiny 1.8 L to 2.5 L. They all use a 27-degree DOHC valvetrain with directly actuated hydraulic (HLA) bucket lifters. The K- series also feature a highly-rigid, all-aluminum split-crankcase engine block design with 4 & 6 bolts for each main journal, internally balanced forged crankshaft with long, lightweight forged carbon steel connecting rods. They were designed to be as compact as possible for short-hood front-wheel drive applications. A unique innovation of the K-series is the introduction of Variable Resonance Induction System (VRIS). Based on the Helmholtz resonance principle, the intake manifold is equipped with 3 chambers tuned to a specific resonant frequency. The computer dynamically switches between each resonant chamber to achieve the appropriate resonant frequency for the engine's RPM.