Cylinder block

A cylinder block, comprising:

• a block body, in which are defined
• a plurality of cylinder bores,
• a water jacket surrounding a periphery of the cylinder bores, and a through channel that extends between the cylinder bores adjacent to each other and through which coolant from the water jacket flows, wherein
• the through channel includes a first upstream channel of which an upstream end is connected to the water jacket, a second upstream channel of which an upstream end is connected to the water jacket, and a downstream channel that is connected to a downstream end of the first upstream channel and a downstream end of the second upstream channel,
• a downstream-side portion of the first upstream channel, including the downstream end, extends in a columnar shape,
• a downstream-side portion of the second upstream channel, including the downstream end, extends in a columnar shape,
• an upstream-side portion of the downstream channel, including the upstream end, extends in a columnar shape, and
• a channel cross-sectional area of the upstream-side portion of the downstream channel is larger than a channel cross-sectional area of the downstream-side portion of the first upstream channel, and also is larger than the channel cross-sectional area of the downstream-side portion of the second upstream channel,
• wherein the downstream end of the downstream channel opens to a deck face,
• the first upstream channel is columnar,
• the downstream channel is columnar, and
• as viewed along an axis extending from the first upstream channel, the first upstream channel overlaps the downstream end of the downstream channel.