Gizmos
The Redneck Racing Gizmo is designed to bypass the tunnel coolers when the engine is warm but the water in the tunnel is cool, like when you've been riding and stop for a drink. The water in the tunnel coolers can drop about 80 degrees lower than the water in the cylinders. So when you fire the sled back up, that cooler water starts circulating around the hot metal in the cylinders. It (cold shock) can cause the cylinder to shrink around the piston and scuff the piston. The Gizmo's internal thermostat closes off the tunnel coolers from the rest of the cooling system and slowly bleeds the cool water from there into the operating-temperature water in the engine part of the system. The cooling system's operating temperature also raises about 15 degrees over what the stock cooling system runs at, so the tunnel stays cleaner and lighter.