Redesigning an exhaust manifold with a water jacket core improved the overall system robustness and durability for a recreational boat engine. The component, cast by AFS Corporate Member Benton Foundry (Benton, Pennsylvania), achieved improved functionality of the system by eliminating moisture contact with the O2 sensors from either condensation or direct contact with water. Complex cored cooling channels, only possible with the metal casting manufacturing process, allowed the design to avoid injecting water into the exhaust stream until the end of the engine’s y-pipe via a sprinkler.

Excess water is allowed to bypass the exhaust manifold and adapter elbow for pressure relief. The adapter elbow and manifold are vented through a check valve to allow air to escape during the initial system fill and eliminate possible “vapor lock” in the water jacket.

Benton Foundry produces both the manifolds and the adapters for this system.

The design facilitates system robustness and adds durability to eliminate warranty claims and improve the customer experience. The customer can thermostatically control the raw water used to cool the exhaust system to eliminate condensation on the O2 sensors in cold water. There is also allowance for venting during system fill with water and pressure relief for system pressure spike during the warmup phase while the thermostat is closed. The design also eliminates any possibility for water reversion to contact O2 sensors.

Click here to see this story as it appears in the January/February 2020 issue of Casting Source.