TECH CORNER: The Quest To Be Cool
In the quest to keep my 572 Merlin Big Block as cool as possible, I went back to school "per say" and tested my existing knowledge against the latest technical advice available. There is a plethora of information on this very subject and like anything that people can have an opinion on, there will be debates. My intention is to only share the facts on cooling and not my opinion. I will focus on fluid facts as this was very scientific and was what I needed the most.
As a life-long gearhead, I knew the benefits of having an electric fan instead of a mechanical one. I knew about the benefits of having a push/pull fan. I knew that shrouding your fan is a must. I knew about thermostats and how to select the proper temp range and how to even modify your existing one for more flow. These are the things we tend to learn from our gearhead community and are learned from hard work and garage bonding. Since the garage is a little more fun than school, (although school did have a lot more girls) we tend to turn our brain off when the conversation gets too technical or when math gets involved. So from one gearhead to another, in the most simple form of sharing this with you that my simple mind could think of, here are some helpful facts and tips on fluids used to help keep an engine cool:
Tap Water is simply water that you get when you turn your faucet on. The quality of this water depends greatly on where you live in the world. Some of you have wells, which tend to be high in minerals and other impurities. Some of you have city water, which has other chemicals in it such as chlorine. Because of the unpredictable and diverse quality in tap water, it is frowned upon when using in a cooling system.
Distilled Water is simply water that has many of its impurities removed through a process called distillation. Distillation involves boiling the water and then condensing the steam into a clean container. Distilled water does not have the impurities and minerals that tap water contains.
De-ionized Water or De-Mineralized Water are two different types of water that have no minerals in it, and there for is a sponge looking to absorb minerals, like the radiator, and other metals in the cooling system. A matter of fact, when plumbing for a de-ionized water system, you need to use stainless steel or plastic.
Antifreeze is an additive, which lowers the freezing point of a water-based liquid. It can also raise the boiling point of water-based solutions. Water absorbs more heat and therefore cools better but is corrosive to the working parts of a cooling system. Antifreeze also offers anti corrosion benefits, which when used in a proper ratio with water is a very efficient and mechanically safe combination. Don't be fooled by the urban legend that a richer antifreeze mixture will keep the complete system cooler. In fact, it works just the opposite. Antifreeze has a higher viscosity rating than plain distilled water. By raising the antifreeze mixture percentage, you lower its ability to adsorb heat from the engine. Because water absorbs heat better than antifreeze, the higher the antifreeze mixture percentage also reduces the radiator's ability to get rid of the coolant heat.
Water Wetter is a unique wetting agent for cooling systems, which can reduce coolant temperatures by as much as 30 degrees Fahrenheit when used with water alone. The benefits of this product greatly diminish when used with glycol-based antifreeze resulting in 2-3 degree Fahrenheit reduction in a 50/50 mixture. This liquid product can be used to provide rust and corrosion protection for plain water applications such as a racing engine where antifreeze is prohibited. It also provides much better heat transfer properties than glycol-based antifreeze.
Here are some quick facts about the Freezing Point and Boiling Point of water and ethylene glycol (C2H6O2):
• Pure Water freezes at 32 F and boils at 212 F
• 50/50 mix of C2H6O2/Water freezes at -35 F and boils at 223 F
• 70/30 mix of C2H6O2/Water freezes at -67 F and boils at 235 F
It is now time to go back to school and learn how pressure effects the boiling temperature of a liquid. The pressure cap on a cooling system is the key to raising the boiling point of the 50/50 mix of antifreeze and distilled water. For every pound of pressure cap rating, the boiling of point of the above mixture raises approx 3 degrees. If you had plain water in your cooling system with a 15-pound pressure cap, the water would boil at 257 degrees. If you had a 50/50 mix of antifreeze and water the coolant would boil at 265 degrees with a 15-pound cap. The boiling point would raise to 270 degrees, if you had a 60% antifreeze mixture with a 15-pound cap. If you had a 70% mixture the boiling point would raise to 276 degrees.
I pray that this has helped you in some way. I know it has certainly helped me understand the science behind the different fluids available and the power of a pressure cap. Like I mentioned in the beginning of this article, there is so much more to cooling, like selecting the correct radiator, shroud, fan, and thermostat. I came across a well-written and rather witty guide to how keep your engine cool by the geniuses at Griffin Thermal Products. They are a leader in radiator construction and their products are made in South Carolina, USA. I urge you to check out their site at www.griffinrad.com, as it contains not only some of the best products available, but a wealth of knowledge to aid you in your quest to be cool.
Here are Griffin's 10 Commandments for cooling:
1. Thou shall make room for an adequate cooling system in the design of your engine compartment. First things first. When planning your performance vehicle, remember that you're building it to drive, not to sit and steam. Plan adequate space for the cooling system including the radiator, fan, shroud, over flow tank and mounting brackets. Talk with a cooling specialist to help you size the system for your vehicle, engine and driving habits. Consider the investment compared to the total cost of the car. 2. Thou shall shroud thy radiator when using a fan. Fans move air through the radiator assisting in cooling the engine. A fan without a shroud is better than no fan. But, consider this. At idle or cruising speeds, you need the entire cooling system working at its optimum. An unshrouded fan is moving air through only the portion of the radiator equal to the surface area of the fan. For example, on a '32 Ford, the area of a 15.50" fan is about 189 sq. in.; the core of the radiator is approximately 371 sq. in. This means that almost 49% of the unshrouded radiator is not receiving any benefits of the fan. Shrouding your radiator lets the fan pull air through the entire core. 3. Thou shall use an electric fan. Rule of thumb. Only choose a mechanical fan over an electric fan if it's your farm tractor. An electric fan is preferred because when you need a fan the most (at idle or cruising speeds) an electric fan is delivering maximum air independent of engine RPM's. Fans that move 2000-2300 CFM's are worth the investment. Preference should be given to a "pull" vs. a "push" fan. Mounted on the engine side of the radiator, a pull fan does not interfere with air flow at highway speeds. All shrouded fans should be on the engine side of the radiator. 4. Thou shall consider airflow or how a radiator cools. Without adequate air flow, a radiator is just a reservoir for hot water. Coolant transfers heat to the tubes; the tubes transfer heat to the fins; air moving through the fins dissipates the heat from the radiator. You need sufficient openings to the radiator that channel adequate air to the entire surface of the radiator. You must have a radiator design that allows the air to pass effectively through the radiator (wider and taller is better than thicker). You must consider how the heat will be evacuated from the engine compartment. 5. Thou shall use the proper water pump pulley ratio. To obtain the maximum operating efficiency rate for your water pump at highway speeds, you should overdrive the pump by 30-35%. Check your pulley selection. Most after market pulleys are a 1:1 ratio. For a 30-35% overdrive, the crank pulley should be approximately 7 7/8" and the water pump pulley approximately 5 3/4". This overdrive provides proper coolant flow from the engine and through the radiator. 6. Thou shall consider the effects of the pressure cap. The higher rated the pressure cap, the hotter the water has to get to boil. One pound of pressure raises the boiling temperature 3°F. A 16-pound cap raises the boiling point to 268°F. If your engine is designed to run at 200°F, a 14-16-pound cap should be sufficient. Running a higher pressure cap to prevent boil over is putting a band aid on another problem that needs to be fixed. Higher operating pressure places additional stress on the entire engine system and increases the potential of hoses bursting and possible injury. 7. Thou shall understand the operating temperatures of today's modern engines. All engines have "normal" operating temperatures. Running engine temperatures well above or below recommended temperatures could cause damage. Most of today's engines operate in the 180°-210°F range. Pollution laws, new oil blends and higher combustion gasoline have forced engine design changes that have increased operating temperatures over the past decade. Consider your engine's normal operating temperatures when selecting your radiator's cooling capacity. 8. Thou shall always use a thermostat. The thermostat controls engine coolant temperature. It stops the flow of coolant through the radiator until the coolant reaches the thermostat's preset temperature. Operating your engine within its temperature parameters reduces wear, helps control emissions and turns any moisture in the crankcase to steam where it is removed by the PCV system. Select the right thermostat for your engine's operating temperature range. 9. Thou shall protect thy cooling system with recommended coolant. It is essential to use a premium coolant that protects the radiator, other metal parts and seals. Today's coolants are a scientific blend that normally includes water wetter and corrosion inhibitors. Use of a coolant that contains no silicate is recommended. Silicate is an abrasive and can cause gel formation and water pump failure. A 50/50 mix of coolant and distilled water provides the best overall cooling efficiency. Proper maintenance (regular flushing and changing of coolant) will extend the life of your system. 10. Thou shall spend thy money wisely. If you are having cooling problems, begin by looking at the least expensive fixes first. 1) Add an electric fan. 2) Shroud your fan. 3) Check your belts and hoses. Slipping belts or collapsed hoses mean trouble. 4) Check your radiator cap. 5) Flush and refill with premium coolant. 6) Use the proper thermostat. 7) Clean the radiator of foreign materials. 8) Overdrive the water pump 20-30%. 9) Check your water pump. Should cooling problems persist, it may be time for a new performance radiator from Griffin.