one of the problems that plaguing hot rods everywhere is overheating. when an engine passes the radiators ideal operating temperatures, they are known to overflow. and if the system isn't equipped with the proper radiator cap to allow for overflow; kaboom. both for efficiency and for operator safety, we decided to include a blow off valve. if the water temperature reaches the brake lines unhappy place( point of failure), the seals or even the lines themselves will burst. or simply get too hot to further collect heat. Either way not good.