cooling system

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bradf
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cooling system

Post by bradf »

Here is a bit of knowledge, actual facts with numbers, and it certainly goes against old school thought. I do love opening a can-o-worms.

Remember that all automotive cooling systems must cool when the engine is running as 30% of the energy produced is lost through engine heat through the cooling system and oil and 30% is lost through exhaust heat. A gallon of gasoline produces about 19,000 to 20,000 BTUs of heat energy when it is burned, which is enough to boil over 120 gallons of water. Antifreeze is not for a running engine that produces exess heat in as much as it is for one that sits outside during a worst case scenario of a Minnesota winter. Agreed, antifreeze does raise the boiling temperature to about 250-275 degrees. So does the pressurized 15 lb cap. Antifreeze keeps the cooling systems prime cooling agent (water) from freezing.

Water is assigned a value of 1.0 as a cooling medium. Using water as the standard, anti-freeze has a cooling value of 0.6. This means that anti-freeze is only 60% as efficient at transferring heat as water is. What this means is that a 50-50 mix is not as efficient as straight water. In point of fact, is only 80% as efficient. The formula to figure out the cooling system efficiency is percent water X 1.0 plus percent antifreeze X 0.6 to equal the cooling system efficiency. Using the recommended 50/50 mix ( .50 x 1.0=.50 plus .50 x 0.6= .30 equals 80% system effectiveness.) Using 75% water and 25% anti-freeze results in 90% system effectiveness. (.75 x 1.0 = .75 plus .25 x 0.6= .15 equals .90% system effectiveness.) I use this ratio during the winter. No serious race engine uses antifreeze. These engines don’t sit out in freezing Minnesota winters. Antifreeze does however provide water pump lubrication as well as rust inhibitors. Aluminum motorcycle engine/cylinder/head castings don’t rust. Cast iron automotive engine blocks do rust. Again, during my racing time I talked to many top notch engine builders i.e. Ernie Elliot, Jack Roush, Leonard Woods, and some Italian guy from Italy with Ferarri racing that built both the WSC and the F-1 engines. There was not a drop of antifreeze in any of these engines. It was also prohibited due to the dangers of it creating extremely slippery racing surfaces after a wreck. Everyone used pure water and Water Wetter which contains lubricating agents and surfactants. Surfactants keep the water slippery or low surface tension, like a detergent does, and thus keeps the water in contact with metal instead of allowing the heat to create areas of steam bubbles where no water can have direct contact with the metal. The top of the heads is where this is most common. If you add app. 6 caps of Water Wetter (amount suggested by Water Wetter for a KDX cooling system of 37 ounces) to this, you have as highly effective a coolant system as you can obtain which will still provide water pump lubrication and proper coolant flow.
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Post by canyncarvr »

The point being that 'antifreeze' in 'cooling systems' is a juxtaposition of terms that is senseless?

No can-o-worms there. You won't find anyone disagreeing with the premise. Not even me! ;)

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Post by KDXGarage »

Hi. Thanks for bringing up the topic. I am in the middle of tearing down my top end, so it is a good time for me to think about what to put back in it.

"Aluminum motorcycle engine/cylinder/head castings don’t rust. Cast iron automotive engine blocks do rust." Aluminum does corrode, however. Isn't the water pump impeller made out of steel? What all is steel and what is aluminum?

What PSI were these racing engines' cooling systems run at?

I think there is a big difference in the airflow through the radiator for cooling on a race car vs. a dirt bike. What is the average speed of a race car? I would imagine quite a bit higher than 18 or 24 mph. :grin:

The information on the Water Wetter site says:

"The boiling point of water treated with Red Line using a 15 psi cap is 250°F compared to 265°F at 15 psi for 50% glycol."

How hot does a liquid cooled KDX run?
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Post by Indawoods »

Never had a hot KDX.... guess I will stick to the cheap anti-freeze method! :razz:

Might try the 75/25 mix this time though....
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Post by Indawoods »

I have heard that 2 stroke water cooled bikes like to overheat in high elevations and this may be a good product for those situations, but normally a good 50/50 mix should work just fine. If it ain't broke... don't fix it! :lol:
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Post by KDXGarage »

On their website and the technical document, it said something about since it reduced the temperature of the head that the timing could be advanced since the octane requirement was less. That might be interesting to look into.

Royal Purple and Engine Ice have some cooling products, too.

I understand the surfactant part, but I don't see how they say it makes it cooler, then they say it is 15 degrees less cooling protection than 50/50. Maybe it cools better and protects worse??
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Post by bradf »

The cooling capacity to of the two radiators was engineered by determining factors such as square inches of metal fins, material (aluminum), number of rows, flow rate, average air temp, air flow etc. These two radiators cool just 37 (or 47) ounces of coolant. Also, the cylinder and head have cooling surface. This system is designed to operate efficiently up to a certain ambient air temp and with a certain amount of air flow through them. There comes a point when either the ambient temp is too high or the airflow is too low for the system to dissipate the amount of heat it needs to keep the coolant below a predetermined temp. Cars have fans to make up for air flow. All this said to say this. There may come a time when the either factor of temp or air flow will create over heating. The use of 50/50 will overheat and boil off before the pure water will. There are two areas of concern: 1 being hot spots on the head where the coolant can't absorb and remove the heat fast enough which will create steam pockets: 2 being that any coolant boiled over into the overflow tank is no longer available to cool within the engine, which creates an even worse condition. As far as corrosion, iron blocks want to oxidize (rust) because it is the natural state. Aluminum corrodes because of electrolysis, there are two dissimilar metals in a car, iron and aluminum. The steel alloy (contains other metals) water pump shaft will not oxidize near as fast as iron. As far as race cars go, they can use smaller radiators because they are moving so fast. Also, the water is restricted in these engines. There is not as large amount of water running through the radiator as there could be. For instance, the NASCAR engine used a 1 3/8 hole to limit the water flow into the radiator. This slowed the water down to spend enough time in the radiator to loose the heat. If those engines were in a trail bike the radiators would be quite a bit larger.
Last edited by bradf on 04:34 pm Mar 03 2005, edited 1 time in total.
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Post by KDXGarage »

It makes more sense now. Thanks.

Don't take this the wrong way, but you are having a slight case of "Every KDX is just like mine" -itis. :grin: When you say "These two radiators cool just 37 ounces of coolant", you must mean YOUR two radiators. :grin: My two cool 47.334 ounces of coolant.

Thanks.
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Post by bradf »

correction made to exlude the itis of thisis postis
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Post by KDXGarage »

For someone who is going to use regular antifreeze / coolant and water, are you saying that the higher the concentration of water, the lower the temerature of the cooling mixture will be, but it will have less boilover protection?

For the record, I had 50% Wal-Mart antifreeze / coolant and 50% distilled water. It seemed to work fine. I drained it this morning, and it was looking good (to me). :grin:
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Post by bradf »

I'm not sure I understand that question Jason. The higher the concentration of water will provide a greater ability to transfer heat. This is fact. Boiling in an engine is not simply an engine gets hot then boils the coolant. It starts with hot spots (like a spot on the head usually). This spot is like the bottom of a pan on the stove where small bubbles form. These bubbles push the coolant away from the very spot that needs it which then causes that spot to become hotter because there is no coolant to absorb the heat. The bubble gets bigger, the spot grows hotter, and so goes the reaction. That is why a hot car engine should never be shut off as the coolant will sit in the same spot and not be able to carry away the heat. Many cars have blown because they were shut off when the first sign of steam was seen coming from under the hood. "Boil over" protection is simply raising the temp where water boils like using a pressurized system, or through chemicals. This does not make the engine cooler. The best "protection" is to eliminate or reduce the possibility of boiling by preventing the hot spot bubbles from forming in the first place. Any amount of antifreeze in this "heat" case is detrimental. Now park your bike in Minnie Sota in January and antifreeze is doing exactly what it was designed for.
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Post by skipro3 »

The purpose of the liquid, as pointed out, is as a coolant and not really an anti freeze. (Unless you live in one of THOSE states, but not a problem in California).
So, water is best for cooling until it reaches boil. At that point, the air bubbles that form in the boil block water from wicking the heat away from the engine. So it is only when the water in the bike reaches the boiling point that anyone would have trouble. With a pressurized system, the boiling point is raised. To what, on a KDX, I don't know but my guess would be that the pressurized system with straight water would be sufficiant for the application. My bike runs about 195 and can peak above 230. Sure wish I knew the boiling point of water at, what is the KDX cap, 9 psi?
Anyway, it is my experiance that the hotter you can run the motor, the more horsepower you can generate. So having a cold running engine is not the goal. The goal is to have a hot running engine, just not overly hot or uncontrolled thermal runaway. With that in mind, I run EVENS NPG+. It is designed to not boil and is designed to allow the engine to run hotter than water. Yes, regular antifreeze does the same thing but sooner or later, being aquias in nature, it will boil. EVENS is not water based.

Anyway, that's all just my opinion on the subject. I don't KNOW it as fact, just as experiance.
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Post by bradf »

That is where a thermostat comes into play. If there was a thermostat it could then govern the temp to 220 or so. All my discussion was pointed to show that the best cooling, if needed, usually due to extremes like an AZ dessert ride in August, or long very slow riding conditions in higher than normal temps, would be straight water. I have heard from MSDS's that Evans NPG uses the other glycol (not ethylene but the nature friendly one) and adds the same ingredient that Water Wetter uses (which is like salt peter). I saw some fellers up here a few weeks ago that had their radiators covered like the big rigs do to keep the heat in. But it was in the mid 30's. Just as Ski said, a certain amount of heat is necessary.
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Post by KDXGarage »

EVENS NPG+, I knew there was one more. I remember someone talking about evacuating the system before using that.

bradf, I think you may be referring to propylene glycol. That is what the Engine Ice stuff has in it.

Your further explanation helped out. Thanks for that. I never had to wonder about this tuff when I was riding my '87 KDX200 (air cooled).
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Post by wanaride »

Bradf, thanks for your great explanations in this thread. Maybe I'll look for some Water Wetter at the dealer tomorrow Lord willing.
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Post by skipro3 »

Yea, the EVANS can not be mixed with water and you have to evacuate the whole system. If you spring a leak out in the woods and use water, then when you get back to the barn, you need to start all over again.
I use the EVANS because the 220 habitually runs hot and mine is no exception. I especially like it because it doesn't expand when warmed up like water does, so I don't need an overflow tank. I took mine off to increase airflow over the radiator and so far, every time I check the coolant level, (cold of course) it is right up to the neck on the filler.
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Post by Indawoods »

That's interesting Ski.... no expansion. That's worth looking into.
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Post by skipro3 »

Yes, it was strange. I removed the overflow tank on a suggestion to help with air flow. I figured that the vent tube would weep some fluid out, so I routed it to drop onto the pipe. That way I could tell when it happened by the odor of antifreeze evaporating when hitting the pipe. I never detected an odor, so the next day I checked the level. It was down but only by a couple of ounces. ( That's a about 2 shot glasses to you Wib). I topped it off and it did it once more on the next ride. After that, I capped it a third time and figured that the radiator fluid expanded about 2 ounces worth and would just run it a tad low. When I checked the level after that third time, it no longer was venting fluid, it was at the top. My guess was that this last ride, the bike just didn't get as hot. After a few more trips, it remained at the top. I figured that there must have been a bit of air in there and it was burped out the first couple of trips.
Interesting note though. The first few days of 100+ degree temps here, my bike dripped a few drips of antifreeze out the overflow tube just sitting in the garage. I have no idea why a hot garage would expand the fluid and not a ride on the bike itself, but that's what happened. I haven't checked the fluid level in several rides, so I just went out to check. It's right up to the top still. Temp in the garage is 58 degrees. Brrrrr!
One other note. EVANS does not make my bike run cooler. It does stay in the system without boiling up to well over 400 degrees though. That's why I got it. My bike, during the summer, will run up to 240, maybe more on hard long pulls and hills. I didn't want to risk regular antifreeze. With the EVANS, I've tried to get that bike to the point it would overheat. I couldn't. In fact, the hotter it got, the better it ran. My legs would start to get uncomfortable due to the heat, even through the boots, but no signs that the engine temps were causing any harm. I used some pretty sophisticated temperature measuring and recording instruments to document this while riding. I compared my temps to a co-rider's KDX200. My bike was as much as 35 degrees warmer during a typical outing.
I've got a theory that the warmer engine temps result in less spooge too. It would seem that more of the spooge would burn or vaporize if the motor was running hot. Anyway, the hotter days result in much less spooge, that's for sure.

*****EDIT*****
One more note: My radiator cap is stamped "1.1" It must be a pressure rating. My son's 1994 Mazda B2600i 4x4 pickup truck has a radiator cap of the exact same dimensions but marked ".9". I ran his cap for a couple of rides and the coolant vented. So I guess the fluid might expand, but my cap is of sufficiant rating to keep it in. Maybe my cap is bad and won't pressure relief at all, I don't know, I've never had it checked.
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Post by Hellbender »

I wonder why they don't put fins on the cylinder and head in addition to the radiators. That, by itself, used to keep our bikes cool enough, so they must remove a large amount of heat.

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Post by motorider200 »

Hellbender wrote:I wonder why they don't put fins on the cylinder and head in addition to the radiators. That, by itself, used to keep our bikes cool enough, so they must remove a large amount of heat.

HB


My guess is that the radiators were found to be sufficient enough for cooling and it was maybe cheaper/easier to manufacture cylinders without them.
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