Keeping the engine cool


22 replies to this topic
  • Kasjok

Posted December 05, 2008 - 01:07 PM

#1

As most of us now, distilled water is able to keep the engine cooler compared to pre-mixes of ethylen- glycol. I was wondering how marginal the temperature difference and , whats more important, the performance difference would be.

As I am I am only racing MX and our tracks are fast outdoors type, then I thought I could experiment a bit how lean I could with the premix ( maybe even pure water) with out boiling it over.

Also, maybe someone knows the difference of distilled and sterile water?

  • Wiz636

Posted December 05, 2008 - 02:18 PM

#2

You need the mixture to raise the boiling point of the coolant and also to lubricate the water pump.

I would not run pure water.

  • Smokeslider

Posted December 05, 2008 - 03:54 PM

#3

sterile is free of bacteria and organisms...not really free of minerals per se.
Use distilled and why exactly are you trying this? Just curious.

  • Kasjok

Posted December 06, 2008 - 05:42 AM

#4

I am not trying it yet. I was just curious how much cooler could I get the engine running, when using more destilled water, like 1:4 or something.

  • finthat

Posted December 06, 2008 - 08:32 AM

#5

If you want cooler I would use a premix and then add what is called a wetter. This stuff will make it run cooler. I know guys run that in their atv's if they do alot of hard mudding in thick swamps with not much speed to get air over the rad and they also have junk plugging the rad, cat tails ect.

  • triton5150

Posted December 06, 2008 - 12:06 PM

#6

i switched to ice in all my bikes and it made a big difference and also rejetting is important.

  • Deathdeelr

Posted December 06, 2008 - 10:09 PM

#7

I believe the water wetter is actually just alcohol or some other chemical that is meant to do exactly what the ethylene gycol is meant to do, that is raise the boiling point and lower the freezing point of the coolant. Water wetter was originally used in aluminum radiators before the invention of anti-corrosion additives when the gycol would eat the aluminum. I don't think it would make any difference.

Distilled water is water that's boiled and condensed to remove minerals. As said before, sterile water is water that's free of bacteria. If you have hard tap water (that is water that is rich in mineral deposits), then you should be using distilled water to cut the EG anti-freeze 50:50. Those minerals don't bode well with the engine and radiator internals.

My advise, just go with a good quality EG coolant and mix it in a jug 50:50 before you pour it in to the bike. Make sure you change your radiator cap once a year or so and that should give you a good 250-270 degree boilover protection. Don't run a lower pressure cap. Each pound less of pressure reduces your boiling point by 2 or 3 degrees. If you run the stock pressure cap and you develop a leak somewhere, FIX THE LEAK. You'll be making more trouble for yourself if you don't.

Distilled water may have a higher heat transfer rate than a EG coolant mix but it boils at the same 212 degree mark. Go with the mix.

  • locktite

Posted December 09, 2008 - 08:31 PM

#8

Look up Evans Coolant.

  • grayracer513

Posted December 10, 2008 - 07:31 AM

#9

I believe the water wetter is actually just alcohol or some other chemical that is meant to do exactly what the ethylene gycol is meant to do, that is raise the boiling point and lower the freezing point of the coolant. Water wetter was originally used in aluminum radiators before the invention of anti-corrosion additives when the gycol would eat the aluminum. I don't think it would make any difference.

False on both counts. Water Wetter is a surfactant, and works by breaking the surface tension of water, creating a better thermal connection between the water and the metal surfaces it touches. This improves the transfer of heat from a part to the water, or vice-versa. It verifiability does work, but it has no anti-corrosion properties.

Distilled water may have a higher heat transfer rate than a EG coolant mix but it boils at the same 212 degree mark. Go with the mix.

Water does not boil at 212 in a cooling system. The 1.1 bar cap on most MX bikes raises the pressure of the cooling system to 16 psi, at which pressure straight water will not boil until 235-240 degrees F.

Many, if not most or all, super moto race organizers require water only (along with catch cans).

The question of whether the engine runs cooler or not with certain coolants than others gets complicated. First, the fact that an engine boils over less with one or the other says more about the boiling point of the coolant than the heat of the engine. An engine running water only that is on the verge of boiling may be running 150 degrees cooler that an engine running Evans NPG that is not boiling.

Boil/no boil is not a good way to compare coolants. The only correct way to evaluate them is to measure the temperature of the coolant leaving the engine as it enters the radiator, the temperature of the coolant leaving the radiator and returning to the engine, and the actual metal temp of the combustion chamber dome. A more effective coolant will have a higher temp leaving the engine, and loose more heat in the radiator than a less effective one. It would also lower the head temp, which would skew the direct comparison a bit more.

Boiling point is important for two reasons. The first is coolant retention. Obviously, no coolant is any good once it escapes. Less well understood is the fact that the liquid cannot cool the part that is boiling it because at that point, it is not a liquid. At the heat source, where boiling is occurring, the thermal bond between the liquid coolant and the part is broken by the gas bubbles as they form, and the part gets hotter much more quickly, causing the heat to spiral out of control. So, while water is in fact a better coolant than glycol or mixes, it is useless if it boils too readily in the engine, and the bike is better off with something that will remain liquid.

An interesting question is whether it is really beneficial to cool the engine at all. Obviously, metals have their limits, and the engine must be kept cool enough that the oil can properly lube it, but otherwise, the idea of igniting gas in the first place is to extract heat from it. If you then turn around and draw off as much of this heat as you can into the cooling system, you are working at cross purposes with internal combustion, and wasting some of the energy created.

Overall, water will cool better than a glycol/water mix (either EG or PG), but the difference in head temp will only be 20-30 degrees, and it often becomes more important to prevent boiling than it does to reduce temperatures. OTOH, raising the boil point beyond what's needed is not necessarily a good idea, IMO. Coolants like Evans NPG run a very high boil, about 435 F. This might be needed in extreme off-road racing conditions, but if not required, it can also allow your engine to run at internal temps well beyond the flash point of the engine oil while giving no external indication until after a lube failure occurs.

In a nutshell, the question of which coolant to use is one of balancing priorities.

  • Deathdeelr

Posted December 11, 2008 - 01:17 AM

#10

See, you learn something new every day. I didn't know sanctioning bodies limited coolants. I also learned something about Water Wetter. Thanks Gray.

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  • davidrussell41

Posted December 11, 2008 - 10:53 AM

#11

I run Evans coolant in my 06 450 mainly because of the or lack of electrolsis with the aluminum in the engine.

  • grayracer513

Posted December 11, 2008 - 11:29 AM

#12

Electrolysis will occur with NPG eventually if you leave it in too long.

  • BC3

Posted December 12, 2008 - 09:30 AM

#13

http://www.redlineoi...cts_coolant.asp


I use it in my street rod and it works.....

  • tdamore

Posted December 12, 2008 - 12:33 PM

#14

I use engine ice and have had no problems even in the super tight rocky Los Padres National Forest where you rarely get out of second gear, sometimes not even first.

  • mitchicle

Posted December 12, 2008 - 03:57 PM

#15

I got turned on to engine ice from a local shop that did my engine rebuild after it grenaded. Been using it ever since and haven't had any problems. I like that it comes premixed.

  • Smokeslider

Posted December 12, 2008 - 04:09 PM

#16

+1 on the engine ice. Haven't had any overheating issues yet with this product.

  • ncmountainman

Posted December 12, 2008 - 04:23 PM

#17

gray, i've been using evans npg-r in my last 3 bikes and am quite certain although it has a 400'+ boiling point it will not boil unless something is mechanically wrong. it does however transfer less heat than 50/50,even less compared to straight water. but....how it works is by reducing molar cavitation around the cylinder walls. when that happens with conventional 50/50 or water the situation will snoball into a overheating event if the conditions persist.
everyone used to go into a panick when i'd sit there idling my 450 and even the big bore 488 for 5 mins while waiting for slower riders,it reaches a point roughly 20'-30' higher than normal and stays there no matter what ya do to it;as long as the fluid is circulating it will not continue to climb.
as far as damage from running a little hotter? i've found less than normal wear on any internal parts :thumbsup:

  • NortonMoto

Posted December 12, 2008 - 07:41 PM

#18

Can you mix WaterWetter with purple engine ice?

  • BC3

Posted December 13, 2008 - 10:58 AM

#19

[COLOR="Blue"]Check with Redline.....[/COLOR]

  • grayracer513

Posted December 13, 2008 - 11:24 AM

#20

Can you mix WaterWetter with purple engine ice?

Redline states it will work with ANY antifreeze/coolant.

gray, i've been using evans npg-r in my last 3 bikes and am quite certain although it has a 400'+ boiling point it will not boil unless something is mechanically wrong. it does however transfer less heat than 50/50,even less compared to straight water. but....how it works is by reducing molar cavitation around the cylinder walls. when that happens with conventional 50/50 or water the situation will snoball into a overheating event if the conditions persist.
everyone used to go into a panick when i'd sit there idling my 450 and even the big bore 488 for 5 mins while waiting for slower riders,it reaches a point roughly 20'-30' higher than normal and stays there no matter what ya do to it;as long as the fluid is circulating it will not continue to climb.
as far as damage from running a little hotter? i've found less than normal wear on any internal parts :thumbsup:

This is somewhat what I said, although the specific temp info is interesting. I assume you have a trail computer with a temp sensor? Where is the sensor located?

One of the things about radiators is that the greater the difference between the internal and external temp is, the faster the rate of heat exchange becomes. Like water flowing to a low spot, heat moves from hot to cold, and the bigger the temp delta, the more "downhill" it is, so what you're saying about the temp reaching a plateau makes some sense.

"Molar cavitation" is the technical term for "spot boiling", and that's what I was referring to as I spoke of the boil point cutting off the cooling ability of the coolant. Fluid in circulation is less prone to this than standing fluid is, though.





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