Quote:
Originally Posted by Fourthbean
Quick question for anyone that knows, does antifreeze help/hinder cooling or is it just to raise the boiling point?
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This is straight from my buddy Chris who runs a mobil mechanic service. it's kinda long but good reading. he also wrenchs on a buddies outlaw car
so he knows his stuff pretty good.
"A 50/50 mix in the radiator is WAY too much coolant! Especially in warm climates. You will rarely ever require more than 30% coolant/anti-freeze, and even then, only if you live within the Arctic Circle. 20% would be more practical. Coolant serves five purposes, none of which keeps the engine cooler. It:
1) Acts as a lubricant for the water pump.
2) Helps protect the hoses from the inside (BTW, save your used coolant for wiping down your tires! It will restore the "new tire" look, rather than the "glazed donut" look you get with aftermarket tire dressings).
3) Helps reduce the electrolysis that naturally occurs in cooling systems that deteriorates metal.
4) Lowers the freezing point of the cooling system mixture
5) Raises the boiling point of the cooling system mixture.
This last one is the most deceptive. A cooling system in proper working order is a sealed system. That means that no outside air can get in, and as the temp rises, the system becomes pressurized. Pressure, combined with no added air, will keep the system from boiling under normal circumstances. By raising the boiling point, coolant actually raises the cooling mixture temp. The info on the sides of the coolant containers brag about being able to reach 260 degrees before boiling over, but guess what: DAMAGE CAN OCCUR AT OR BELOW 260 DEGREES!!! You want it to boil over before it gets that hot! That way you will stop driving, and let the system cool down. Coolant also retains heat, which makes it harder for the cooling system to dissipate the heat, like it's supposed to. Here in California, I never use more than 10% coolant, even when I go to the snow in the mountains. I worked for Bill Elliott in 1998, and was shocked to discover that those cars, with their 900 horsepower engines that drove for 500 miles straight, averaging 7000+ rpms, ran with 100% water in the cooling system. The only thing they use coolant for in NASCAR is to measure the cc's of the combustion chambers in their heads. Because they don't use coolant, they have to use a higher pressure rated radiator cap (28 - 30 psi), but since everything is new, it can easily handle that much pressure. Don't believe the hype: coolant actually makes your engine run hotter!
From the Red Line Oil website:
THERMAL PROPERTIES
Water has amazingly superior heat transfer properties compared to virtually any other liquid cooling medium - far superior to glycol-based coolants. Water has almost 2.5 times greater thermal conductivity compared to glycol coolants. Mixtures of glycol and water have nearly proportional improvement due to the addition of water. Most heat is transferred in a cooling system by convection from hot metal to a cooler liquid as in the engine block or from a hot liquid to cooler metal surfaces, as in the radiator. The convection coefficient of liquids in a tube is a complicated relationship between the thermal conductivity, viscosity of the liquid, and the tube diameter which determines the amount of turbulent flow. Since 50/50 glycol solution has about 4 times the viscosity and only 70% of the thermal conductivity of water, the thermal convection coefficient for a 50/50 glycol solution is approximately 50% of the coefficient for water. Water in the cooling system is capable of transferring twice as much heat out of the same system as compared to a 50/50 glycol coolant and water solution. In order for a 50/50 glycol mixture to reject as much heat as water (amount of heat rejected is independent of the coolant), the temperature differentials at the heat transfer surface must be twice as great, which means higher cylinder head temperatures.
COOLANT EFFECTS ON PERFORMANCE
Under moderate load conditions, each percent glycol raises cylinder head temperatures by 1?F. 50% glycol raises head temperatures by 45?F. This increase in temperature will raise the octane required for trace knock levels by typically 3.5 octane numbers. A car equipped with a knock sensor will retard the timing to compensate for the increase in octane requirement by approximately 5?, which will reduce the maximum brake torque by about 2.1%. Racing vehicles not equipped with knock sensors can advance timing for increased torque.
For maximum temperature reductions use the most water and the least antifreeze possible to prevent freezing in your climate."
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