Thermalnator gaskets are a unique high temperature shielding gasket which replaces the stock intake manifold gasket. It’s cooling properties reduce heat by stopping metal to metal contact between the intake manifold and the engine block, acting like an intercooler. The basic formula for this is for every 5 degrees F increase in intake air temp, air density is reduced by 1%. The denser the air is, the better the gain in horsepower.