Engine coolant.  Not the normal subject of our attention in the quest for increased power generation, but maybe it should be. In an internal combustion engine, heat is power and how that heat is utilized will ultimately determine the level of power generation from a hydrocarbon-fueled engine. Jack Evans, founder of the cooling systems company that bears his name, has spent years studying the thermal transfer of conventional engine coolants and quantitatively identifying their strengths and weaknesses. Consequently, he has developed a nonaqueous propylene glycol engine coolant that allows for increased power  generation, reductions in BSFC, and a corresponding rise in octane tolerance in any engine. To fully comprehend the breakthrough technology that is represented by the evans NPG cooling system, we need to review the theories of thermodynamics as they relate to an engine.

THE IMPORTANCE OF HEAT

During the burning process of combustion in a engine, the release of the end gases’ potential energy traditionally can create flame front temperatures on the order of 2,500°F. This is not to be confused with material surface temperatures of the combustion chamber, squish area and piston top, which historically are not allowed to reach the flame front temperature due to the limited term they are exposed o this thermal force, along with the parallel issue of the presence of coolant in the engine. Ideally, the desired goal would be to have an adiabatic engine, or more simply put, have no heat loss from the beginning to the end of the combustion event. Even with the evolutionary changes that are apparent in today’s OTTO-cycle engine, the amount of work derived from the fuel consumed still only remains at 20 percent, which is not appreciably better than the first engine ever built.

Unknown to most, anything that is done to an engine to increase Brake Mean Effective Pressure (BMEP), which the aftermarket refers to as horsepower, is centered around an increase in heat, to create a greater force to expand against the piston during the power stroke. Through leaner air/fuel ratios, forced induction (turbo and superchargers), oxygen bound in a nitrogen carrier (nitrous), higher compression ratios and increases in volumetric efficiency through airflow improvements (cylinder head design and optimization) and the elimination of pumping losses (larger throttle bodies, air intake kits and high-flow air filters), the main goal of each is to generate heat. The problem with the internal combustion engine is its ability to waste 80 percent of the heat generated from these improvements. The necessary temperature fluxes that are inherent to this design center around the need to have internal parts such as the piston remain dimensionally stable during the combustion process. This is necessary to maintain clearances and provide lubrication through oil with its inability to withstand temperature and the negative effect heat has on volumetric efficiency, from thermal transfer to the incoming charge.

To date, the cooling systems of internal combustion engines function through forced convection. Heat that is transferred through a fluid in motion, and between a fluid and a solid surface in relative motion, this said motion being induced by gravity, is referred convection. If the motion of the fluid is induced by an external force, then it is referred to as forced convection.  Automotive cooling systems’ incorporation of a water pump as the heat transfer process to be identified as forced convection.

LATENT HEAT OF VAPORIZATION

The heat of vaporization is a natural process that takes place when a liquid changes to a gas. Deceiving at first, by definition, it would be assumed that the transformation of liquid to a gas is creating heat. But quite the contrary.  While the composition of the liquid is being changed to a gas energy is consumed in the form of heat.  The area where the transformation takes place gives up heat to the transformation

The engine cutaway shows the sustained nucleate boiling without vapor barrier (B), while A represents the vapor barrier and corresponding hot spot that would be present during the same condition with normal engine coolants.

process and this heat is carried away by the newly formed gas. This is the law of physics that creates cooler charge air temperatures in carbureted engines when compared to dry-flow port fuel-injection systems. The conversion of the liquid fuel to a gas in the carburetor and intake manifold plenum pulls the heat from the manifold runners, effectively creating a substantial drop in charge temperatures.

The ability of a liquid to transfer heat during a conversion process to a gas is usually measured in calories/mole or more commonly in BTU (British thermal units). The term mole is a convenient way to introduce a mass unit based on the molecular structure of the matter. Hence, the mole is the amount of substance that contains as many molecules as there are carbon atoms in 12g of carbon. This is the common definition when referring to the term mole in regard to a spark ignition engine.

The top casting is of a production GM water pump, while the more efficient Evans design is seen below it. The larger and more radiused enclosed blades of the Evans impeller compared to the GM unit account for its superior flow rates.

If a liquid comes in contact with matter that is above the temperature of its own boiling point, then a reaction occurs that is identified as nucleate boiling. The transformation of the liquid to a gas that takes place during nucleate boiling applies to the theory of heat of vaporization, removing heat from the matter that has invoked the nucleate state. Ideally, if this liquid is transferring heat by forced convection, then the ability of the liquid to move away from the nucleate site and recondense becomes paramount. If the fluid has a high surface tension (surface tension of a liquid, or its frictional flow losses, is measured in a value referred to as Dymes/CM; higher this number the more “clingy” the fluid is), then a vapor barrier will form between the coolant and the matter that needs to be cooled, effectively insulating it from the coolant and its ability to
 

The importance of using a coolant that can remove heat from the cylinder head is apparent in this generic engineering plot of typical temperatures.  Note the difference between aluminum and cast iron.  All values are in degrees Centigrade.

transfer heat, with the result being a localized hot spot. Conversely, if the vapor barrier is able to break away from the parent material, then it can cool and recondense, and it allows room for fresh liquid to come in contact with the desired area to be cooled. Then the complete process of nucleate boiling and the heat of vaporization takes place, and the corresponding removal of heat when fresh coolant arrives at that location.

NUCLEATE BOILING’S POSITIVE IMPACT ON DETONATION

Since the water jacket of a cylinder head surrounds the combustion chamber and exhaust port. the transfer of heat from these components is crucial in the quest to suppress abnormal combustion. If nucleate boiling takes place with a liquid that has a very high surface tension (very clingy), and the fluid that is used has a very low nucleate state, then its ability to release from the nucleate sight and recondense becomes diminished. The temperature to boil also has a direct affect on the fluids’ ability to remove heat from the desired component. To substantiate this, let’s exaggerate an example. If fluid A has a boiling point of 100° F, when fluid A comes in contact with a surface of 101° F or greater, it will go into its nucleate state. At this point the only hope that this fluid has in cooling the subject piece is to break away from the nucleate sight and recondensing and allowing fresh liquid to go through the same process. Regardless of fluid A’s surface tension, its inability to remain liquid will have the net affect of only being able to create at most a delta surface relationship of 1° F. Given the same scenario with fluid B, but increasing this fluid’s ability to withstand boiling to 200° F, even without the benefit of the breakaway tension being altered, the fluid’s ability to remove heat through vaporization is almost double that of fluid A.

This applies to the coolant’s ability to quench detonation by either eliminating or contributing to a hot spot in the combustion chamber. The positive affect that the elimination of detonation is to the readers of a publication such as HTP, where the focus is on late-model performance, with either forced induction or nitrous assists is substantial. This is not to say that the same theories aren’t just as effective on normally as pirated applications. Negating the effect detonation has on engine reliability and only focusing on the narrow goal of increased performance, the ability to utilize a coolant that will have a high nucleate boiling state and low surface tension is crucial to vehicles with closed-loop timing controls. The hysteresis of knock dictates that once abnormal combustion is started there is a disproportionate amount of timing that needs to be removed to quench the detonation. This relates to even the slightest amount of detonation requiring the removal of substantial amounts of spark advance and thus horsepower.

THE EVANS NPG COOLING SYSTEM

Now that the thermodynamics of the cooling system have been explored, the attributes of the Evans NPG system can be discussed. Actually designed as a system to maximizes the performance of the NPG coolant, this product is a series of components that work in conjunction to maximize the desired results. First and foremost is the patented Evans NPG coolant, which boasts the following statistics:

Evans NPG Coolant vs. ethylene glycol/water (EGW) mix 50/50.

1. 369° F boiling point at 0 psi for Evans vs. 252° at 14 psi for EGW
2. Increases in the molar heat of vaporization: 12,500 calories per mole for Evans vs. 9,750 calories per mole for EGW
3. Decreased surface tension: 35 dynes/cm for Evans to 56 dynes/cm for EGW
4. Lower freeze point: -70° F for Evans vs. compared to -38° F for EGW
5. Evans NPG coolant is nontoxic to animals and plants
 
 

Evans offers a complete line of water pumps for a multitude of applications for the enthusiast who is looking to optimize the use of coolant.		Ancillary cooling systems components such as pulleys and overflow tanks round out the Evans product line.

In essence, what the Evans coolant does is raise the nucleate state of the liquid to allow for more thermal transfer from the engine, but it also possesses the unique ability to move quickly from its nucleate state to recondensation. This is accomplished by its very low dymes/cm rating and high boiling point. Due to these characteristics, aspects of a traditional cooling system need to be slightly modified to support this new composition.

Due to the broad based appeal of the Evans system, with thousands in use in a myriad of applications from long-distance tractor trailers to every type of racing engine, Jack Evans has decided to market his product in a building-block method, Offered in different stages, it actually allows the end user to “tune” his cooling system for each application.
 

Areas identified with a dot are actual measured piston temperatures, the lines represent calculated values.  Measured in Centigrade, this subject engine was a 2.5-liter 4-cylinder and these readings were obtained at 4600 rpm at WOT.		Temperature distribution on a typical exhaust valve in Centigrade during sustained load.  The Evans coolant with its 369°F boiling point is essential to help arrest abnormal combustion.

INSTALLING THE EVANS SYSTEM

Since the Evans coolant possesses different flow and thermal characteristics than normal EGW, some changes are in order. First, there is no need to use a pressurized cooling system, but an overflow bottle is necessary due to the expansion rate of the coolant. Evans markets 0- and 4-lb. caps for most radiators. The low-pressure cap is used to keep coolant loss in check on late-model engines. To totally optimize this system, a high-flow Evans water pump, thermostat and radiator should be installed. Working with data from the field, most late-model performance cars, unless approaching the 650-hp level, can reap substantial performance gains with just the installation of  the Evans coolant and high-flow thermostat. Realizing the huge potential for power generation through the use of this coolant, Evans has designed many ancillary components to maximize the potential for late-model fuel-injected engines. Pulleys to increase stock water pump speeds, water pump application for TPl, 5.0s and Buick GNs along with radiators.

The actual installation of the coolant is very straight-forward, with the only critical area being the draining of the complete cooling system, block, manifold and heater core. This is easily done by the removal of the lower radiator hose and simply flushing the system.

SUMMARY

With the arrival of the Evans cooling system, technology once again has leaped forward in the quest for reduced emissions and increased power. With the cost of the coolant retailing for $30 per gallon (the typical V8 uses 3.75 gallons), the cost-to-benefit ratio is the best in the industry. The concept of this technology, if embraced by the end user, will allow for substantial power gains in a late-model performance car, especially if it is using forced induction or high compression.

Another benefit is that the water is completely removed from the cooling system so that components that would normally deteriorate from corrosion are now not affected. Run your car at the drag strip? With the Evans system those long cooldown periods are no longer necessary. Want to limit the possibility of detonation? Simply switch over to Evans and its chemical properties will work to remove hot spots from the com bustion chamber.

Most people are skeptical of claims of “power in a bottle,” and in most cases their caution is warranted. With the Evans Cooling System, though, there really is power in the bottle. Jack Evans should be admired for his ability to identify a weak link in a seemingly forgotten area of engine development and for bringing to market a product that does more than it promise.

So no matter what type of late-model vehicle you drive, pour in the Evans and pour on the power.