GM LS Coolant Bypass Crossover Plugs 1pr

The ALLSTAR PERFORMANCE GM LS Coolant Bypass Crossover Plugs are steel, zinc-plated cap and plug fittings designed specifically for GM LS-series engines. This pair blocks off the factory coolant bypass passages on LS-series engine blocks, a critical modification for builders transitioning to high-performance cooling systems or eliminating unnecessary bypass flow in custom cooling configurations.

Constructed from steel with zinc-plated finish, these crossover plugs resist corrosion while maintaining integrity under engine bay temperatures and coolant pressure. The zinc plating provides baseline protection against rust in standard cooling environments, making them suitable for both street and competition builds. Proper installation of bypass plugs ensures coolant flow direction aligns with your custom radiator and water pump configuration, preventing air pockets and circulation inefficiencies that degrade cooling performance.

These plugs serve engine builders, high-performance shops, and enthusiasts customizing LS engine cooling systems for street rods, race vehicles, and engine swaps. Eliminating factory bypass passages allows full control over coolant flow, enabling use of modern thermostat housings and direct-flow radiator cores that maximize heat rejection. The pair format covers both crossover block ports, simplifying the transition from OEM cooling architecture to integrated performance setups.

LS-series engines remain the foundation of countless custom builds across multiple platforms. Whether upgrading cooling capacity, consolidating ancillaries, or optimizing thermal dynamics in a conversion project, blocking bypass flow is standard practice among serious builders working with LS powerplants.