PREP Spark Plugs are engineered to relieve cylinder pressure under extreme operating conditions; this is to prevent the engine from destroying itself. In the event of a cooling system failure all of the engine components will increase in temperature… including the spark plugs. The pressure relief port in PREP Spark Plugs is also designed to open during engine overheating. This will help prevent engine overheating damage in two ways:

• Audibly alert the vehicle operator of impending engine damage, and
• Reduce the heat generation and rate of heat transfer to engine components

Both of these require further explanation.

PREP Spark Plugs relieve cylinder pressure from a running engine through a vent port which is closed prior to abnormal engine operation, in this case excessive engine temperature. Passenger car engines typically produce cylinder pressure of about 800psi; a cylinder leak to atmosphere is easy to detect, like a loud exhaust manifold leak. A leaking exhaust manifold can actually sound like an out of adjustment valve "tapping." This sound will alert the vehicle operator of trouble, such that the vehicle can be stopped at a convenient and safe location. The engine will continue to run and produce power, but power output will be diminished because the compression ratio of the engine is decreased, and some of the fuel's energy is wasted to the surroundings (wasting heat to the surroundings is better than continuing to overheat the engine, in this case).

Heat is generated in an engine by the rapid oxidation (burning) of the fuel, usually gasoline. Some of the heat energy is converted to work by driving the piston downward and applying torque to the crankshaft. Any remaining or unavailable heat energy which cannot be converted to work must be rejected to the cooling system. A cylinder leak directly allows some available heat energy to escape the cylinder directly to atmosphere. Ordinarily, in the absence of a cylinder leak, the unavailable heat energy escapes to atmosphere through the exhaust valve and into the exhaust system, and ultimately to atmosphere. Allowing some heat energy to escape the cylinder through a vent port in the spark plug reduces the amount of energy that is available to do work or to be rejected to the cooling system. It's kind of like trying to fill a bath tub with a leaking drain plug. Eventually the tub will fill with water, but it will take longer than if the drain plug holds all of the water in the tub.

PREP Spark Plugs provide an additional margin of safety against engine overheating. Perhaps the engine temperature gauge is not accurate, or even functional; perhaps the indicator light or coolant temperature sensor does not work. Even if the instrumentation is intact and fully functional, there is no assurance that an inexperienced or preoccupied motorist will heed the warnings. Without undue criticism, it should be noted that youthful and elderly motorists may not react appropriately to such instrumentation (the only appropriate action is to seek a safe location to stop the vehicle). PREP Spark Plugs make the problem of an overheating engine more evident to the motorist, and "buys more time" between problem detection and engine damage.

PREP Spark Plugs are manufactured from existing, high quality spark plugs of any design (platinum, multiple or exotic electrode, resistor) and by any manufacturer (NGK, Bosch, AC, Autolite, Champion or any other manufacturer). Unless the spark plug vent port is caused to open due to engine malfunction, PREP Spark Plugs function identically to the spark plug from which they are made. Installing PREP Spark Plugs is easy, just like installing any ordinary spark plugs; the benefits only appear in the event of pending engine damage. After PREP Spark Plugs have vented to prevent engine overheating, they must be replaced, but the cost of PREP Spark Plugs is very small compared to the cost of an overheated engine.