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Three Easy Ways to Improve Engine Cooling

Three easy ways to improve <a href='https://www.thumpertalk.com/link/click/1133/' rel='nofollow' data-ipsHover-target='https://www.thumpertalk.com/index.php?app=autolink&module=links&controller=content&id=1133' data-ipsHover target='_blank'>cooling. <i class='fa fa-external-link'></i></a>png

This month I want to discuss three easy ways to improve engine cooling for your dirt bike or ATV and explain why they are effective.

As improvements are made to an engine that increase its power, the amount of heat the engine will create will also increase. Effectively removing heat from the engine and cooling it is very important as the power output of the engine goes up. The cooler an engine runs, the more power it can produce. There are three ways that the aftermarket attempts to improve the cooling system of a particular engine.

1. Increase flow through the cooling system.

2. Increase the cooling capacity of the radiators.

3. Increase the pressure of the cooling system.

Let's dive in.

1. Increase flow through the cooling system
The flow through the cooling system can be increased by installing a water pump impeller designed to increase the flow rate of the coolant. The reason increasing the flow rate of coolant works is because the rate of heat transfer from the engine to the cooling system is directly proportional to the mass flow rate of coolant. This is thermodynamics jargon, but there are two key parts to consider. First, how much coolant is flowing, and second, at what speed the coolant is flowing. The more coolant that flows and the faster it flows will reduce the temperature difference between the point where the coolant enters into the engine and where it exits. This next part is not quite as intuitive. When the temperature difference between the inlet and outlet is reduced, the average coolant temperature is lowered. When the average coolant temperature is lowered the engine will run cooler. This is why fitting a water pump, which increases the flow of coolant through the engine, improves cooling.

impeller.JPG

2. Increase the cooling capacity of the radiators
Radiators consist of a series of tubes and fins which run from the top to the bottom of the radiator. These are often referred to as the radiator’s cores. As coolant enters the radiator it moves through the series of tubes and heat is transferred from the coolant to the fins. Air passes over the fins and heat is transferred from the fins to the air. This transfer of heat from coolant to air is how radiators reduce the temperature of the coolant.

Coolant temperatures can be reduced by upgrading radiators in three ways, by increasing the frontal area of the radiators, by making the radiators thicker, or by using materials with better heat transfer properties for the cores. For all practical purposes, increasing the radiators’ frontal area and improving the core materials is rarely a viable option for dirt bike applications. This is because there is little room for the radiators to begin with and they are susceptible to damage, making the use of expensive core materials a risky affair. Unfortunately, both of these options are better improvements to make before resorting to increasing the thickness of the radiators.

Increasing the thickness of a radiator is not as efficient of an improvement as increasing the frontal area of the radiator. In order for thicker radiators to cool more effectively than their stock counterparts, airflow past the radiators is key. When the thickness of a radiator is increased, air must travel a greater distance through the radiator before exiting. The speed the air is traveling plays a big role in determining how quickly the air heats up as it moves through the radiator. If the air is not traveling fast enough through the radiator, the air temperature will rise and equal the coolant temperature before reaching the end of the radiator. Once this happens, heat transfer stops and whatever portion of the radiator remains will not help with cooling. In order for a thicker radiator to be effective, air must flow quickly enough through it so that the exiting air temperature is at, or better yet, below the coolant temperature. In conclusion, benefits from adding thicker radiators will be more prominent in applications where speeds are relatively high. Whereas in applications where the bike is hardly moving, improved cooling may not be noticeable.

3. Increase the pressure of the cooling system
The last alteration to the cooling system that can be made is to install a high pressure radiator cap. As coolant temperature increases, pressure increases inside the cooling system. The radiator cap is designed to be the pressure release point in the cooling system in the event that too much pressure builds up. This can occur as a result of overheating or a blown head gasket for example. By designing the radiator cap to be the weak link in the system, other parts of the system, such as seals, don’t end up getting damaged from being over pressurized. The radiator cap features a plug and spring on its underside. The spring is designed to compress once a certain pressure is reached, at which point the plug will move upwards and uncover a pressure release hole where excess pressure will be vented.

radiator cap.JPG

The coolant’s boiling point and ability to conduct heat are necessary factors in understanding why a high pressure radiator cap can help improve engine cooling. Water alone boils at 212°F (100°C) while a 50/50 mix of water and antifreeze boils at 223°F (106.1C). Radiator cap pressure designations are usually advertised in bar, with most stock radiator caps designed to withstand pressures up to 1.1 bar (16psi). The more pressure a fluid is under, the more difficult it becomes for the fluid to vaporize, and the higher its boiling point becomes. When water is under 1.1 bar of pressure, the temperature water will boil at is 260°F (127°C) while a 50/50 antifreeze mix will boil at 271°F (133°C). By installing a radiator cap designed to withstand higher pressures, an additional increase in the coolant’s boiling point will be seen. High pressure caps are usually designed to withstand 1.3 bar (19psi) of pressure. This 0.2 bar (3psi) increase in pressure over the stock system will increase the boiling point of water or antifreeze by 8.7°F (4.83°C). This will then bring the boiling point of pure water or a 50/50 antifreeze mix to approximately 269°F (132°C) and 280°F (138°C) respectively.

While this small temperature increase alone won’t do a lot for your engine, coupling a high pressure cap and using coolants with better heat transfer properties can do wonders. Antifreeze (ethylene glycol) alone is not an inherently good conductor of heat. In fact, pure antifreeze conducts heat about half as well as water, while a 50/50 mix of antifreeze and water conducts heat approximately three quarters as efficiently as pure water. This means a cooling system using a 50/50 mix of antifreeze would have to flow faster than a cooling system filled with pure distilled water in order to achieve the same cooling efficiency. What this means for you is significant cooling gains can be made by using distilled water and an additive called “Water Wetter” in place of an antifreeze-water mix. Water Wetter is an additive that improves water’s “wetting” abilities (another whole subject), adds corrosion resistance, and slightly increases the boiling point of water. A high pressure radiator cap in conjunction with distilled water and Water Wetter as the coolant is by far the best route to go for high performance applications where freezing is not an issue. For applications which must still be resistant to freezing, the antifreeze-water ratio can be altered in favor of mixtures incorporating more water than antifreeze so that the cooling efficiency of the mixture is improved. Just bear in mind the freezing point of the mixture as it is thinned with water will be reduced, so you will need to pay close attention to the environment you are operating in so that the coolant is never susceptible to freezing. A frozen coolant system can ruin an engine and makes for a very bad day!

I hope you enjoyed this post on three easy ways to improve your engine’s cooling. 

Screen Shot 2017-03-30 at 12.04.03 PM.png

One more thing before I wrap up! April is Autism Awareness month, and here at DIY Moto Fix we couldn't be more excited to announce that we will be donating 15% of all profits made in April to AutismMX.

If you haven't heard of AutismMX, this amazing non-profit brings Autism awareness to the motorcross community. Founder, Matthew Dalton, created this non-profit after finding that motorcross was an amazing way to connect with his autistic son.

At DIY Moto Fix this non-profit also touches a chord with us. Our filmmaker and photographer, Kelsey Jorissen, loved dirt biking with her autistic brother throughout their childhood.

The Autism MX Project focuses on four areas:

  • Autism MX Day Camps are days for ASD kids and families to have the chance to ride AMX’s little dirt bikes and quads and enjoy the sport of motocross.
  • Team Autism MX Sponsoring amateur MX racers, riders as well as sponsoring AMA pro racers. Through doing so, they are getting out the word on Autism Awareness to millions.
  • AMX Puzzle Piece Apparel from shirts, graphics, goggles, to help stand out and support Autism Awareness.
  • AMX Ride Days for Autism Awareness AMX celebrates Autism Awareness and is a fundraiser for The Autism MX Project.

So for the entire month of April - if you buy a booka video, even a poster - 15% of that purchase will go towards AutismMX and their amazing cause.

Thanks for reading and have a great rest of your week!


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Glad to see that it did touch on the point of Higher pressure Radiator Caps will increase the whole system pressure - but should have put a little more emphasis on the stress it can put on gaskets, seals, and such.  The cap is usually the cheapest and easiest, however a higher pressure cap should be a LAST resort to better cooling.   The engine has plenty of cooling ability once you blow a gasket from a high pressure system on old gaskets and kill the engine.

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Another way is to add a fan. I crashed my trials bike yesterday and pulled a wire from the thermostat. The bike starting knocking after a couple of minutes and boiled over soon after before I found the loose wire.

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17 hours ago, Truman Sparks said:

Worried about boiling over?

Run Evans Coolant

http://www.evanscoolant.com/how-it-works/

 

Never worry about boiling over again.

 

 

Despite Evans claims to the contrary, their product has significantly less heat capacity than conventional coolants so will always make the engine run hotter.  It is intended for classic vehicles because it operates at low pressures and will not stress fragile old hoses and gaskets.  Installation of Evans requires very careful flushing of your system to get rid of all existing coolant or you lose this benefit.  Going back again when you find out it's not working is also a pain.  Evans coolant is completely unsuitable for most high performance motorcycle engines.

Also note in the original article, discussion of increased pump rates missed the fact that, at high rpm, high volume pumps can cavitate, leading to LESS flow in the system.  They are most suitable for slow riding situations.  Replacing a worn pump with a new OE pump is a great way to restore lost cooling capacity on older bikes.  Finally, using the correct type of coolant specified by the manufacturer is important.  In particular, switching from silicate-containing to non-silicate (OAT) coolants can lead to sludge build up.

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"When the temperature difference between the inlet and outlet is reduced, the average coolant temperature is lowered.

No true.  The average temperature stays the same.  The engine rejects the same amount of heat to the cooling system in both a low flow and high flow situations.  so the average temperature has to be same, as does the average temperature delta between engine block/head and coolant.

What it does do for you and keep the peak coolant temperature lower, so you don't get localized boiling.

Michael

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These seem to be spend money ways.  How about some repairs or Home brews?

Is the radiator blocked up?  Inside or outside.  Getting your radiator cleaned out could help.  Outside is obvious, clean the fins and unplug it.  Inside is harder.  I had a VW that overheated in blizzards.  Mechanics couldn't figure it out.  Finally the radiator cracked. A new radiator cured all problems.  Radiator shops can boil out radiators that are clogged.

Are you riding how the bike was designed.  If you ride slowly, add a fan.  If you are play riding take some trips out to faster areas.  Are there better shrouds for air flow?  Did you modify the bike and impede airflow?

Temperature gauge.  Even a cheap aquarium thermometer can be useful.  If you know the temperature when your bike starts puking water, then you know when to back off, or if you need repairs, or cleaning.  An external mounted sensor won't give exact temperature, but you can note when the bike overheated.  I plan on adding one to my XR400, so I can tell when the bike is running too hot.

Oil cooled, air cooled.  Cooling the oil is important too.

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On 4/10/2017 at 0:29 PM, Slartidbartfast said:

Despite Evans claims to the contrary, their product has significantly less heat capacity than conventional coolants so will always make the engine run hotter.  It is intended for classic vehicles because it operates at low pressures and will not stress fragile old hoses and gaskets.  Installation of Evans requires very careful flushing of your system to get rid of all existing coolant or you lose this benefit.  Going back again when you find out it's not working is also a pain.  Evans coolant is completely unsuitable for most high performance motorcycle engines.

Also note in the original article, discussion of increased pump rates missed the fact that, at high rpm, high volume pumps can cavitate, leading to LESS flow in the system.  They are most suitable for slow riding situations.  Replacing a worn pump with a new OE pump is a great way to restore lost cooling capacity on older bikes.  Finally, using the correct type of coolant specified by the manufacturer is important.  In particular, switching from silicate-containing to non-silicate (OAT) coolants can lead to sludge build up.

Hi,

Right up front here: I work at Evans Coolant. I usually don't enter into conversations on forums simply due to time, but I thought I'd clarify a few things here.

Evans was started in car racing on pavement road courses in the GT1 class (later followed by Trans Am and some NASCAR road course events). Classic cars are a good market for us because of the preservation aspects: non-corrosive, no electrolysis, no pressure, and no need to change the coolant out over time (see Jay Leno). It does have great properties for the intense conditions in racing as well and is being used by a majority of the top motorcycle teams whether they'll admit it or not.

We do state that anti-freeze conducts heat better than our coolant, just the same as water conducts heat better than antifreeze. The issue with either is that the boiling points of antifreeze and water are too close to the operating temperature of the fluid. When water boils, it takes up over 1,200 times the space as a vapor as it does as liquid; this is why a steam engine works. That expansion force pushes the liquid away from the metal surfaces inside the engine leaving the metal at those locations bare and unprotected. A rise of coolant temperature of 10 degrees is nothing compared to the metal temperature spike of hundreds of degrees at these locations. These are the detonation causing hot spots and in extreme cases they can lead to head warping and head gasket failure. With this in mind, a hotter coolant temperature does not equal a hotter engine.

Yes, it is very important to get the water out of the system before pouring our coolant in because otherwise you won't get the benefits that you're paying for. Our coolant is a blend of glycols, the same basic chemicals already found in antifreeze. If you need to add water or antifreeze in an emergency to get home, it will cause the coolant to revert to the properties of antifreeze, but no worse. It will not gel, separate, or do anything catastrophic.

Pump cavitation is a byproduct of the boiling point/pressure/vapor equation that comes along with the presence of water. The low pressure (inlet) side of the pump lowers the boiling point of the fluid at that location. If the fluid is close to its boiling point, it will boil and cavitate the pump, especially with aggressive pitch or high speed impellers. Waterless coolant resists cavitation so much that there is no cavitation limit established in the new ASTM standards for waterless coolants (D-8085).

I believe that all powersports coolants are silicate free. The seals in powersports coolant pumps are different than those used in automotive so I always tell people, even if you don't use our coolant, please don't use an automotive antifreeze!

With regard to the components in a cooling system, we like to see people get the plastic parts out and replace them with better quality items like single piece silicone hose kits and pumps with metal impellers like Boyesen. A fan isn't critical, but I wouldn't ell someone to take it off unless they were looking to save weight. With our coolant, I like to see people go back to the standard OEM rated pressure cap. Our coolant expands about 7% as a fluid, so it will build whatever pressure the cap is rated to.

If you get out to a GNCC, stop by and see us. If you're at an MX, Flat Track, or other event, look for our stickers and ask those teams about it. Thanks for letting me give our side here and now I'll go back to enjoying Thumpertalk under my non-Evans name. (and no, I'm not posting on cooling topics under that alias.) 

 

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43 minutes ago, Evansguy said:

Hi,

Right up front here: I work at Evans Coolant. I usually don't enter into conversations on forums simply due to time, but I thought I'd clarify a few things here.

Evans was started in car racing on pavement road courses in the GT1 class (later followed by Trans Am and some NASCAR road course events). Classic cars are a good market for us because of the preservation aspects: non-corrosive, no electrolysis, no pressure, and no need to change the coolant out over time (see Jay Leno). It does have great properties for the intense conditions in racing as well and is being used by a majority of the top motorcycle teams whether they'll admit it or not.

We do state that anti-freeze conducts heat better than our coolant, just the same as water conducts heat better than antifreeze. The issue with either is that the boiling points of antifreeze and water are too close to the operating temperature of the fluid. When water boils, it takes up over 1,200 times the space as a vapor as it does as liquid; this is why a steam engine works. That expansion force pushes the liquid away from the metal surfaces inside the engine leaving the metal at those locations bare and unprotected. A rise of coolant temperature of 10 degrees is nothing compared to the metal temperature spike of hundreds of degrees at these locations. These are the detonation causing hot spots and in extreme cases they can lead to head warping and head gasket failure. With this in mind, a hotter coolant temperature does not equal a hotter engine.

Yes, it is very important to get the water out of the system before pouring our coolant in because otherwise you won't get the benefits that you're paying for. Our coolant is a blend of glycols, the same basic chemicals already found in antifreeze. If you need to add water or antifreeze in an emergency to get home, it will cause the coolant to revert to the properties of antifreeze, but no worse. It will not gel, separate, or do anything catastrophic.

Pump cavitation is a byproduct of the boiling point/pressure/vapor equation that comes along with the presence of water. The low pressure (inlet) side of the pump lowers the boiling point of the fluid at that location. If the fluid is close to its boiling point, it will boil and cavitate the pump, especially with aggressive pitch or high speed impellers. Waterless coolant resists cavitation so much that there is no cavitation limit established in the new ASTM standards for waterless coolants (D-8085).

I believe that all powersports coolants are silicate free. The seals in powersports coolant pumps are different than those used in automotive so I always tell people, even if you don't use our coolant, please don't use an automotive antifreeze!

With regard to the components in a cooling system, we like to see people get the plastic parts out and replace them with better quality items like single piece silicone hose kits and pumps with metal impellers like Boyesen. A fan isn't critical, but I wouldn't ell someone to take it off unless they were looking to save weight. With our coolant, I like to see people go back to the standard OEM rated pressure cap. Our coolant expands about 7% as a fluid, so it will build whatever pressure the cap is rated to.

If you get out to a GNCC, stop by and see us. If you're at an MX, Flat Track, or other event, look for our stickers and ask those teams about it. Thanks for letting me give our side here and now I'll go back to enjoying Thumpertalk under my non-Evans name. (and no, I'm not posting on cooling topics under that alias.) 

 

Thank you a ton!  That is some wonderful information.  Its always nice to see companies (or their employees) not pushing a product, but information. I am curious about the silicone hose recommendation - I've been reading that while silicone hoses are better for cooling, they also allow water to escape and lower the coolant levels.  Does this not happen with waterless coolants?

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27 minutes ago, Thump_Stump said:

Thank you a ton!  That is some wonderful information.  Its always nice to see companies (or their employees) not pushing a product, but information. I am curious about the silicone hose recommendation - I've been reading that while silicone hoses are better for cooling , they also allow water to escape and lower the coolant levels.  Does this not happen with waterless coolants?

I really appreciate what you said about information VS sales pitch. I don't want to be that sales guy and I don't think I need to.

I'm not sure that I've heard anything about silicone hoses allowing water to escape, but here's what I do know.

The heavy OAT antifreeze formulas from when they first came out were abusive to silicone hoses. This was back when Dexcool was getting known for turning black and gunky, clogging radiators and ruining engines. A hose company contacted us and paid the great compliment by telling us that they tested a lot of coolants and ours was the best in terms of reactions with hose materials and pressures. They reported that the heavy OAT fluids would eat into the silicone, especially on the outside radius of a bend. Once antifreeze had access to the threads inside the hose, it would degrade them and the hose would later fail. This was with the old OAT formulas and in HD truck applications; I don't think these issues were seen in automotive or powersports applications. The OAT formulas have since been ratcheted down to a level where we don't see the destructive properties anymore.

Another possibility might be that silicone is a little more delicate than stock hose material. If someone tightens a hose clamp too much it can cut into the hose. On the other side, if they are too careful and don't tighten enough, then the hose can slip off or maybe leak. If coolant can get to the threads inside a hose, it will "wick" along the threads and weep out at the end of the hose. No damage can be seen, but it leaks.

Lastly, people often misunderstand coolant loss. They will say it evaporates or something, but the system is essentially sealed. Coolant will leave a tight system by two ways. Fluid expansion will purge some out or it will be forced out by boiling. Our coolant and antifreeze both expand about 7% as a fluid at operating temperature. If you fill the radiator to the top and ride the bike, you'll find the level has dropped after it cools down. If you didn't boil the coolant, this is your operating level and it will go to that level no matter how many times you top up. If you lose more than that amount, it is a sign of a leak or of overheating. I saw a bike at an Endurocross that would overheat every lap when it was up on the woodpile. The guy would get stuck on the pile and you'd see the steam cloud coming out of the vent. As soon as he got rolling again it would clear up. It did this every lap, but I'm sure the rider had no idea. A top MX team told me about their KX450 practice bike. They thought they had a blown head gasket, but after tearing it down found that it was fine. They just couldn't believe that the bike was losing that much coolant from overheating. The truth is that the practice bikes get way more abuse than the race bikes.

Let me know if you find something more about silicone hoses and coolant loss. It's something I should know about. Thanks

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16 minutes ago, Evansguy said:

 If coolant can get to the threads inside a hose, it will "wick" along the threads and weep out at the end of the hose. No damage can be seen, but it leaks.

I think this is the real answer to "silicone hoses loosing coolant".  Like you said they are more delicate, so even the smallest of nicks will allow for coolant to wick out from the threads.

What about catch cans/reservoirs? I've considered adding one for long tough rides where its possible I'll boil over a little but not have coolant on me.  I dont seem to see them often, but seems like a good safety net.

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7 minutes ago, Thump_Stump said:

I think this is the real answer to "silicone hoses loosing coolant ".  Like you said they are more delicate, so even the smallest of nicks will allow for coolant to wick out from the threads.

What about catch cans/reservoirs? I've considered adding one for long tough rides where its possible I'll boil over a little but not have coolant on me.  I dont seem to see them often, but seems like a good safety net.

A coolant expansion tank won't help cool the bike, it doesn't act as additional capacity. It does allow the system to draw coolant back in as it cools so less fluid is lost. That's good with antifreeze, although in a real overheating situation, antifreeze is lost because it overcomes the tanks capacity and the tank doesn't capture the vapor either. For people using Evans and an expansion tank, I tell them that they will see it moving into the tank at operating temp and then back again as it cools. You don't need to add a tank, though, because the system will purge out as the fluid expands; when the level drops on cool down, that is now your proper operating level. There's no need to top up, the radiators will be full to the top once the coolant gets hot and expands again. Some people prefer to get an expansion tank because they feel things will be more complete, and that's fine too.

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I'll just add my two cents these are race bikes and you can't sit and idle and chew the crap with you buddy for ten minutes you got to keep your bike rolling to keep it cool , Lets say 100 out and your creeping through a canyon at two miles an hour it's going to over heat no matter what!

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