Diesel engines run more efficiently when they're hot. But up until recently, inefficient cooling has limited how hot you can run a diesel before serious damage occurs. Conventional coolants containing water boil (vaporize) around 225^oF near sea level. Cooling systems are pressurized to raise the average coolant boiling point to around 250^oF, but that doesn't solve the real cooling problem, which occurs inside the water jackets of an engine.

Inside the water jacket, heat-stressed metal exceeds the thermal capacity of conventional coolant. Area (A) below shows the coolant boils, forming a vapor barrier at the metal's surface. This vapor barrier acts as an insulator and prevents efficient heat transfer from the metal to the coolant, causing localized overheating and vaporization of the coolant.

Furthermore, this super-heated, vaporized conventional coolant doesn't fully condense back into liquid until it circulates back to the radiator. Once it's returned to the radiator, it remains a gaseous barrier to the heat trying to exit to the air until it's fully recondensed. This means the conventional coolant is constantly losing efficiency as it circulates through the hot engine, and even through the radiator.

Evans NPG Coolant is pure coolant - no water added. The non-aqueous propylene glycol (NPG) boils at 370^oF, greatly reducing vaporization and eliminating vapor problems. Shown, (above right), at Area (B) Evans NPG Coolant bathes the entire cooling jacket and significantly improves coolant surface effectiveness. Heat transfers more efficiently from the metal to the liquid coolant, and is carried off to the radiator for more effective elimination. Furthermore, any vaporized NPG coolant recondenses while still in the engine, so the coolant continues to absorb damaging heat on its way to the radiator.

When you eliminate trapped engine heat in the cooling system, you can modify an engine to run hotter, which increases your engine's efficiency. Optional minor cooling system modifications used in conjunction with NPG Coolant allow the operator to choose raising an engine's operating temperature and thus its power output and fuel efficiency. Usually an operating temperature increase of about 25^oF produces significant fuel economy gains. Evans NPG Coolant carries off the increased heat smoothly and efficiently, eliminating destructive hot spots, cylinder liner and coolant pump cavitation, and uneven cooling problems throughout your entire cooling system.

This isn't theory - it's in actual use by truck fleets and owner / operators who report gains of up to 1.5 miles per gallon fuel savings in engines modified to take advantage of Evans NPG Coolant's increased cooling efficiency. The cost of the changes necessary to take advantage of Evans NPG Coolant improved cooling properties can be recouped in a year through improved fuel economy alone. The elimination of down-time due to cooling system problems, and elimination of the cost of coolant changes are icing on the cake. These advantages, spread out over several units or an entire fleet, result in significant savings.

Because Evans NPG Coolant doesn't "after-boil" (boil over, or vent) in the operational temperature range of a diesel engine cooling system, you can change to a low-pressure or no-pressure cooling system. While anyone servicing a cooling system must remain cautious around hot liquids, the danger of an explosive discharge of coolant from accidental cap removal or component rupture is minimized or eliminated. Low, or no-pressure systems also enjoy reduced hose and gasket leakage, and longer cooling system component life. NPG Coolant is safe for use with all metals and totally non-corrosive to many.