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Ten Rules for Maximum Cooling

themechanic

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Ten Commandments For Maximum Cooling


1. 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, overflow tank, and mounting brackets. Talk with one of our specialists to help you build the system for your vehicle, engine size, and driving habits. Consider the investment compared to the total cost of the car.


2. Use an electric fan.
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 RPMs. 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 airflow at highway speeds. All shrouded fans should be on the engine side of the radiator.


3. Always use the right shroud with your 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 from the fan. Shrouding your radiator lets the fan pull air through the entire core


4. Consider airflow and how a radiator uses it to cool.
Without adequate airflow, 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. 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%. Most aftermarket 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. The pressure cap matters.
The higher-rated the pressure cap, the hotter the water has to get to boil. One pound of pressure raises the boiling temperature by 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. 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. 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. Selecting the right thermostat for your engine's operating temperature range means better performance and longer life.


9. Protect your system with the 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. The 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. Spend your 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. Call the Griffin Customer Service Department at 1-800-722-3723 for assistance in selecting the correct radiator for your requirements.


** WARNING: Improper wiring can cause electrolysis and destroy the radiator. Please make sure radiator is not used as a ground. **



 
Number two is FALSE.
There are countless examples of dudes joining forums to ask for help about overheating problems. Often times they have electric fans that don’t cool nearly as well as the stock belt driven fan
 
Number two is FALSE.
There are countless examples of dudes joining forums to ask for help about overheating problems. Often times they have electric fans that don’t cool nearly as well as the stock belt driven fan
I agree that happens some of the time.

I think CFM's are only part of the equation regarding air flow through the radiator.
 
I am not sure #4 is totally correct for the reasons stated. Any radiator is an air flow blockage for any fan. The larger the area the fan is making air go thru, the less air resistance and the greater the air flow. Ignoring the above point, having the same air flow affecting different radiator surface areas can largely remove the same amount of heat. The area without any forced air flow will always dissipate some heat. Air flow mass and temp delta (ambient air to water temp) are the main factors, and why thick radiators are slightly less efficient with cooling. Because air that travels the farthest is preheated and has the least temp delta for the the rear tubes of the radiator. I would favor fan location towards hot/inlet side of radiator. Also hot air is less dense, but fans I believe are rated for moving cooler air, which should be considered in which side to locate an electric fan.
 
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9. As stated the proper coolant gives you longevity.
But plain water will cool better than 50/50.
If you live in a warm climate where you don't have to provide heavy freeze protection. Its a good idea to match your coolant strength to the lowest freezing temperature you expect to ever see.
 
I've heard water dissipates heat better than coolant but coolant absorbs heat better. Maybe that's why the factory used a mixture.
 
I doubt anybody on the street runs pure water, a 16oz bottle of Hypercool ($7.33? Amazon) provides all the corrosion/water pump lube protection needed, and they claim it cools better than water a bit, and a whole lot better than a 50/50 mix. Plus using a zinc screw in anode can't hurt.
 
The way I understand it is.....
Water is the most effective cooling agent, but coolant lubricates the water pump, provides protection against rust, and increases boiling point. And works best at 50/50. 100% coolant would be a lousy cooling agent.


I just don't understand anybody that buys ready to use coolant. Why pay coolant price for 50% water?
 
The way I understand it is.....
Water is the most effective cooling agent, but coolant lubricates the water pump, provides protection against rust, and increases boiling point. And works best at 50/50. 100% coolant would be a lousy cooling agent.
I agree, although I am a little uncertain what you are referring to in "works best". The problem is as already noted, you may increase boiling point, but you simultaneously give up some heat transfer. Nobody in our applications should need to strive for a 250F+? boiling point, with a properly running normal engine set-up.
I just don't understand anybody that buys ready to use coolant. Why pay coolant price for 50% water?
Although I above mentioned 50/50, I assumed most would mix the ratio themselves, and not buy premixed, which as is rather costly for obvious reasons.
 
Paying full price for a 50/50 mix is indeed stupid. Full jug, off to the drug store for an equal amount of distilled water for a few bucks. Most don't want to be using high mineral content water out of their tap !
 
2. Use an electric fan.
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 RPMs. Fans that move 2000-2300 CFM's are worth the investment.

I have yet to see stats saying that a good factory belt driven fan underperforms electric fans in general. Of course it is dependent on engine rpm.... but do you even NEED 2000-2300 cfm at idle? Mechanical fans move slower at slower rpms, but they also have a helluva relative blade pitch for moving air.

I would love to see some empirical data someday. Until then, mark me down as a tractor fan believer.
 
Real world results here for years now.
493 inched. 12.5 compression. 9" 4800 convertor. 410 gears outback, under drive pulleys.

Here's the cooling system and program.
AFCO 26" Aluminum Nascar radiator.
Single Ford Crown Victoria electric fan with shroud covering entire radiator. core.
160* Mopar Robert Shaw type Thermostat.
Aluminum water pump housing,
Aluminum FlowKooler pump,
Aluminum thermostat housing,
Inner core spring inside bottom radiator hose.
All holes and crevices on radiator support core walls are blocked.

Summer: Completely drain Winter Pure Anti-freeze solution and replace with Pure Distilled water with one to two bottles of water Wetter. 185*-190* at most in the HOTTEST days in NYC traffic with fan running. At night, slightly cooler.

Winter and storage: Completely drain Distilled/Wetter solution and replace with Pure anti freeze. 170*-180*
 
They didn't mention getting trapped air out of the system.
Electric cooling fans are more efficient freeing up power for the engine, but good electric fans are still expensive.
Many of the aftermarket dual electric fan and shroud modules are over $500
On the otherhand, I still run the old Mopar mechanical viscous clutch fan on the Charger
 
Number two is FALSE.
There are countless examples of dudes joining forums to ask for help about overheating problems. Often times they have electric fans that don’t cool nearly as well as the stock belt driven fan
Yup. You beat me to it.
 
After driving 2,500 miles I learned to put a screen in front of the radiator. Had a mass infestation of those giant white puffing seed things fill my radiator.
Didn't notice a change in temp, but I'm glad I happened to check the radiator, and getting the stuff off was near impossible.

I know efi systems have default settings for coolant temperature enrichment and A/F ratio adjustments, so know the minimum temp required.

What about cooling fins, tightly packed to get more in, or loose?
I have an original bb radiator that has close fins, in my car now with no issues, and a recored bb radiator with fins spread out, and I've heard it would be best.

What about a/c condenser, is there min/max on distance from radiator or coverage of radiator?
 
#2..... Griffin sells electric fans and shroud packages.
I'm betting they don't sell mechanical fans
Electric fans only became popular with oem's when they started mounting engines sideways, and they HAD to use an electric fan!
 
One thing about new cars is they have really good thermal control.
Seems most new cars are running piston oil squirters, water cooled oil coolers, some thermostatically controlled.
The engine warm up fast by not running the cooling fans, and some even have electronically controlled thermostats.
The only issue I see is when someone tries comparing the higher running engine temps of a new car and thinking our old cars should also run at 210+ degrees, but our old engine don't have the oil cooling systems designed in like the newer cars, not to mention intake manifolds are metal with heat crossovers which can get very hot and most of us are running carbs on the hot intake causing the fuel to boil in the fuel bowls. The new cars use cooler running plastic intakes and higher pressure EFI. The higher fuel pressure increases the fuels boiling point so it should never vapor lock.
 
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