yz/wr 450 boyesen waterpump


29 replies to this topic
  • crashing_sux

Posted November 14, 2005 - 03:37 PM

#21

No problem. And just to clarify, you don't need to restrict flow for proper cooling, it's an old wives tale with a perfectly scientific explanation (the flow restriction also causes a signifigant pressure increase behind the flow restriction, which reduces the boiling point). They specifically mention this on the Evans website and even sell high flow accessories to get the most out of their coolants.

  • GCannon

Posted November 14, 2005 - 05:03 PM

#22

Good thread guys! Both arguments have merit the problem here is Boyeson is not telling us exactly where they are experiencing their efficiency increases. Is it in pumping (hydraulic) efficiency or are they actually moving more DeltaT from somewhere to somewhere else and if so where? We need more technical details I would love to see the Pump efficiency curves on both pumps and the DeltaT data. :applause:

  • ncmountainman

Posted November 14, 2005 - 05:16 PM

#23

No problem. And just to clarify, you don't need to restrict flow for proper cooling, it's an old wives tale with a perfectly scientific explanation (the flow restriction also causes a signifigant pressure increase behind the flow restriction, which reduces the boiling point). They specifically mention this on the Evans website and even sell high flow accessories to get the most out of their coolants.

i never said anything about restricting flow,i said the slower flow from the stock vs. boyesen seems to work better with more cooling surface area(fluidyne radiators) because of NPG-R's lower rate of heat transfer. maybe you misunderstood what i said about the MX guys cutting the impellars to reduce cavitation at higher rpm's,(at least the team suzuki mechanic i spoke to) resulting in less flow but better cooling in that rpm range, no restriction;just less flow. it probably wouldn't matter as much with us mortals :applause:

  • crashing_sux

Posted November 14, 2005 - 09:15 PM

#24

Not about restricting flow per se, it's just that there is a common myth in cooling that slowing down the fluid to give it more time in the radiator and head increases cooling and I thought that's what you were getting at when you mentioned NPG's lower rate of heat transfer.

From how I read what you were saying it seemed like you were saying you wanted lower flow to counteract the lower rate of heat transfer, when in reality lower flow would lower the heat transfer even further. Is that what you were shooting for?

  • ncmountainman

Posted November 15, 2005 - 05:16 AM

#25

well yes and no , i'm no thermodynamic genius for sure. but i know time is part of the equation. the larger radiators(i believe like 30%)would actually slow the flow more with the same pump rate correct?(well even if it didn't) the slower rate of stock vs boyesen is allowing a fluid (NPG-R)that A) absorbs more heat without boiling. :ride: takes longer to transfer said heat under the same conditions as other cooling fluids. might benefit from going slower through a larger radiator(compared to the same conditions as a stock setup)? instead of speeding the process with a boyesen? at least this is what i've been told by some pro's and the theory seems to hold water,if my bike ran any cooler it might not be hot enough to run properly. oil temps with this set up in the summer were 200-220' where the wr with the boyesen(stock clutch,w/22C) stock 04 rads,would run 240' oil temps. i just did these tests a couple months ago when i still had my wr,with the same oil plug coupler and digital gauge. now i also know that the cam timing for the exhaust valves on the wr makes them run hotter than the yz's,but i'm not sure how much difference is there :applause:

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  • crashing_sux

Posted November 15, 2005 - 08:27 AM

#26

A larger radiator won't slow the flow more, it will add volume to the system which at the same flow rate will make the coolant take longer to make a full pass through the system.

From Evans website:
Hi Performance Suggestions

Install hi performance aluminum tube radiator.
Remove the thermostat and plug all bypass hoses.
Install heater shut off valve.
Increase the pump drive ratio with a smaller pump pulley.

Maximizing Racing Systems

Convert the upper hose and thermostat housing to 1 3/4”OD.
Two -16 AN lines minimum upper hose size.
Install external lines from the rear of the manifold, bigger is better, line size should be -12 AN.
For intake manifold fill location use #E3340 Expansion tank.
Use maximum pump drive ratio possible 80% of crank rpm or more.
For safety reasons all overflow hoses must be connected to an overflow tank or catch can.

And more specifically, from their FAQ:
Question:

In order to increase COOLANT FLOW, the Evans manual suggests eliminating the thermostat and plugging the flow of coolant through the bypass. Will the resultant increase in coolant flow decrease the effectiveness of the RADIATOR?
Answer:

NO. Slower coolant flow through the radiator increases the incidence of temperature drop (T), however, this same slower rate also allows for more heat to be added as coolant flows through the heads. Conversely, higher coolant flow rates through the radiator generate less heat loss with less heat being absorbed with flow in the heads. Important: If the thermostat is removed, the bypass must be plugged, or it will scavenge coolant (flow) away from the radiator which will result in the cooling system running warmer than normal.

So, in effect lower flow results in higher temps going into the radiator, lower temps going out of the radiator, and more importantly, higher temps in the head and engine. That's why I was surprised you got rid of your high flow water pump, and why I'm looking for one. Evans does a lot of nice stuff but they're pretty clear on their website that one thing they do need in general is higher flow. I called and asked why they list tons of modifications for flow in cars and list none for motorcycles and they told me they only say don't bother with modifications to motorcycles because most motorcycles have a pretty much self contained system that is difficult to modify (you often don't have high flow water pumps available and fitting larger radiators is not a trivial task) so they just say to leave it alone, but ideally higher flow water pumps and larger radiators complement their product nicely if you don't want higher engine temps.

Or so they're telling me.

  • ncmountainman

Posted November 15, 2005 - 08:58 AM

#27

Conversely, higher coolant flow rates through the radiator generate less heat loss with less heat being absorbed with flow in the heads.

So, in effect lower flow results in higher temps going into the radiator, lower temps going out of the radiator, and more importantly, higher temps in the head and engine.

well spending more time in the radiator is in esscence slowing the flow,and a comparison between automotive and dirtbikes aren't exactly in the same ballpark. yes,same; but yet not. it all sounds kinda contradictary to me? :ride: well anyhow you look at it i've solved my problem with heat with no boyesen pump :applause: maybe the pump would help more; maybe not.

  • crashing_sux

Posted November 15, 2005 - 10:18 AM

#28

No doubt, if it works there is no reason to spend any more money, I'm going to try it without the pump at first as well. The point of the discussion was not to talk you into buying more expensive toys for your bike, just to clear up a misunderstanding as others besides the two of us will come along and read this thread later.

I think the difference in how we're thinking about this is thinking that spending more time in the radiator is in essence slowing the flow. This is where I disagree, rate of transfer of heat is based on differential of temperature. As you speed the flow you get a more average temperature in the whole system. I'm struggling to think of a good way to describe this here...

Say you have three bottles of water you're trying to warm up by setting them in a pan of boiling water that is 212 degrees, one at a time. The water in the bottles is 40 degrees, (warning, bogus numbers coming up) and after setting it in the pan for 1 minute the water in the bottle is up to 60. After two minutes the water in the bottle is up to 70. After three minutes the water in the bottle is up to 75. The bottle heats less as time goes on because the temperature differential between the bottle and the pan is decreasing. After three minutes you have one bottle that is 75 degrees, and two bottles that are 40 degrees. If you mixed them all together you'd have one big container of fluid that is about 51.5 degrees.

Now if you did the same thing but had three bottles and changed them every minute (higher flow). After one minute you have a one bottle that is 60 degrees and two bottles that are 40. Now you change bottles, and after two minutes you have two bottles at 60 degrees and one at 40. Swap them again and you have three bottles at 60 degrees, for an average fluid temperature of 60 degrees instead of 51.5.

Some people would think this mean the bottles were cooling the pan better as evidenced by a lower reading on the thermometer stuck in the container that you poured all of the water into, but in reality the warmer water is cooling better because it pulled more heat out of the pan. Every second the same water is sitting in the head it's absorbing less and less heat, because it's becoming closer and closer to the same temperature as the head, and every second the same water is in your radiator it's dumping less and less heat for the same reason.

That's why engines run cooler with higher flow, and people often think their motors are running better with lower flow. Thermodynamics don't really care if it's a car engine, motorcycle engine, insulation in your house, or bottles of water.

  • ncmountainman

Posted November 15, 2005 - 10:41 AM

#29

well what of turbulence and cavitation? those are the high flow gremlins in the higher rpm's :applause:

  • crashing_sux

Posted November 15, 2005 - 12:07 PM

#30

Always a possible issue theoretically, especially with the higher viscosity of the NPG products but Evans says that in their testing it has been a non-issue in the real world, that the biggy is just increasing the flow enough to make up for the slower heat transfer.

Turbulence I don't see as an issue at all, can you elaborate on that one? As for cavitation, that's not really an issue with high flow, it's an impediment to achieving high flow. Higher flow doesn't cause cavitation, trying to achieve higher flow improperly (say through turning the water pump at a sub-optimal speed or poor impeller design) can cause cavitation but that really just means you've failed at achieving higher flow.




 
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