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Are you still running a pump in the stock location "inline"? It's ridiculous how painless it is by comparison having an "open" system and drawing directly from a reservoir. No more bleeding, ever. No issues with frothing or cavitation since the pump inlet is unrestricted. I really need to get my HE fixed though, it's been like a year now that I've just been babying the car around due to the leaky HE.
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Yes, my pump is still in stock location. That's because it's horizontal, low down, and in the part of the circuit with the highest pressure and lowest temperature - the general rules for cooling pumps.
If I was going to do anything different, I'd probably add a second CWA-50 in line, though I'd like to get a flow meter in there to see what I'm flowing. It could be that in my configuration I've gone too far from the nominal operating point for the Pierburg, and the impeller is stalling or cavitating. Nick |
Originally Posted by Welwynnick
(Post 7193157)
Yes, my pump is still in stock location. That's because it's horizontal, low down, and in the part of the circuit with the highest pressure and lowest temperature - the general rules for cooling pumps.
That's my understanding/opinion of what's going on anyway. |
There's a difference between static pressure and dynamic pressure.
Static pressure comes from density, gravity, and the pressurisation of the coolant due to temperature. Dynamic pressure comes from the pump, which raises pressure, and the chain of resistances, which lower the pressure. The inlet to the pump is usually the lowest pressure part of the system, and the outlet is usually the highest pressure. Everything else in the system just represents a pressure drop. It would be nice to feed from an open reservoir, high up, but I don't think that's practical in a car, and the reality is that a cooling system at operating temp is going to be pressurised to some extent. For the engine, that helps to raise the boiling point, but that hardly matter for intercoolers. I don't think it matters if the pump doesn't draw from the reservoir, as long as there's no air in the water. Pumps are usually located at the outlet of the radiator, and again usually from a port at the BOTTOM of the outlet header tank, to reduce the probability of air being drawn in. The radiator will add resistance to the inlet, but I don't think that matters in a sealed system, as it's just a pressure drop that is added up around the circuit. Those pressure drops are dynamic pressure drops, and they're relative, not absolute. The pump inlet will still have the lowest pressure in the circuit, regardless of whether it feeds from the reservoir or the HE. More to come.... Nick |
The only way I would see feeding from a reservoir in these cars is sharing the washer fluid bottle (which is what I do on my other car), but in that case you'd probably want to eliminate the heating loop to it. The other option is a trunkmount tank like I have on the S600. Beyond that, you're right, it's fairly impractical given the space we have to work with.
I honestly don't know exactly how the pressure scenario plays out in a closed system. Only that a reservoir system seems to completely eliminate all the bleeding and frothing nightmares...and that's good enough for me. |
I was going to add that I tried different power settingsyesterday when I went to work, and watched the Tecomotive temp gauge. The gauge is very crude – 7 LED’s that represent coolant temps ranging from 0 C to 55 C (the Tecomotive’s control range). I take this to mean LED 1 = 0 C,LED 2 = 9 C, 3 = 18 C, 4 = 27 C, 5 = 37C, 6 = 46 C, 7 = 55 C.
On the way in, I set the pump to 100% continuous. It was a cool morning, 12 C ambient, and onlyLED 2 lit. During the drive, LED 3 lit. When I got to work, I tried taking the cap off, but the coolant was frothing and under pressure, and it spurted out. Therefore when the coolant is frothing, it allows the temperature to increase above ambient. At lunchtime, the IC had heat-soaked and LED 6 was lit. The coolant was hot and frothed, and it still over-flowed. At home time, the weather had warmed up and the engine cooled down. The coolant cooled down to LED 3, and the coolant was clear. I set the pump to 50% continuous, and the temp remained at LED 3 all the way home. When I got home I opened the hood with the engine running and removed the cap. There was no frothing, no pressurisation, no spilling, and the coolant remained close to ambient. The engine also ran better than it’s ever done. This is only a CWA-50 remember, and on the basis of this I’m happy that I’ve got the air out of the system, but I still wouldn’t be happy running at 100% all the time. At 50%, I’d have full confidence in the system, though I’m going back to auto / thermostatic control for a while, and see if that will keep the coolant clear. I have some unusual advantages in my installation: I can positively bleed the IC’s and the HE. I can see the coolant as it’s circulating. I can monitor the coolant temp at the IC outlet. I can manually change the speed of the pump. (What I can’t do, yet, is measure the flow rate in-circuit, which I’m keen to do). None of these are possible with the stock system, so if you change the pump, it’s difficult to tell how the system behaves. Going by what I’ve seen, I wouldn’t be happy running a CWA-50 or -100 under ignition control (12V to the PWM input pin). I can’t say that everyone should run a Tecomotive pump controller, as it’s hard to justify the expense, and it’s a pain to install and use. The SFR Electronics controller is better, with much more displayed information, but it’s more expensive, and theTecomotive does do the job. It could be that the Bosch pump also causes frothing, but no-one will know. Maybe Mercedes found that was the case, and implemented on-demand thermostatic control to allow the coolant time to settle between pulls. On the face of it, thermostatic control is there to protect the pump from burning out it’s commutator brushes too quickly, but Mercedes may be smarter than we realise. Who knows. Regards, Nick |
Is it better to vacuum down an empty system first or one full with coolant ?
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Originally Posted by stuartph
(Post 7207863)
Is it better to vacuum down an empty system first or one full with coolant ?
If the system is empty, there is more air to evacuate, and it will take a long time. If the system is full, coolant will get sucked into the vacuum pump. Vacuum pumps tolerate a small amount of water vapour, but not liquid water. I would say fill it up, then drain half a litre out. That will account for the loss of volume caused by the flexible hoses squashing under vacuum. Nick |
Thanks Nick
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Hi Everybody,
Could you tell me where I'm wrong or point me toward other heat exchange equations/formulae for a heat transfer ratio applicable to HE-s? I'm trying to prove someone wrong. This individual insists, that because of the higher coolant velocity (if I use a larger pump), the heat transfer in the radiator is slower, because "the heat does not have enough time to convect out of the coolant, because it flows too fast" . IMO, he is spewing a shear heresy. The equations cited in this paper http://jullio.pe.kr/fluent6.1/help/html/ug/node245.htm show the only time dependent element,http://jullio.pe.kr/fluent6.1/help/html/ug/img1016.gif=fluid mass flow rate (kg/s), is in the numerator, hence the heat flux q increases proportionally with fluid mass flow rate. In another words, bigger the pump trough-put results in a higher heat transfer and efficiency. http://jullio.pe.kr/fluent6.1/help/html/ug/img1024.gif The same is true for the heat transfer coefficient, http://jullio.pe.kr/fluent6.1/help/html/ug/img1026.gif, http://jullio.pe.kr/fluent6.1/help/html/ug/img1027.gif |
Heat exchanger modelling is very complex, and there isn't really a simple robust equation, there are so many variables and non-linearities.
You're right, heat flux does increase with coolant flow, but it's non-linear. It does plateau at very high rates, so you do get to diminishing returns. You have to have a high pressure to get there, and the pump would have to be very big and powerful. The increase in pumping power required becomes very high compared to the increase in cooling capacity. In normal automotive IC's operating around 0.5 bar, a better pump is a big win. Careful with upgrading the pump though, you can't simply buy a pump with a higher flow figure. High pressure is more likely to increase cooling than high flow. The individual you refer to is certainly wrong, and he's not on his own. He's probably thinking in terms of the coolant temperature change, which is different. Higher flow will certainly result in a lower coolant temperature change, but that is actually desirable, as it's associated with a lower thermal resistance of that heat exchanger. At a system level, that is what you want to achieve. The lower coolant temperature change is compensated by the higher coolant flow rate, and the reduction in the latter is greater than the decrease in the former. Nick |
Originally Posted by MrDangerUS
(Post 7320390)
Hi Everybody,
Could you tell me where I'm wrong or point me toward other heat exchange equations/formulae for a heat transfer ratio applicable to HE-s? I'm trying to prove someone wrong. This individual insists, that because of the higher coolant velocity (if I use a larger pump), the heat transfer in the radiator is slower, because "the heat does not have enough time to convect out of the coolant, because it flows too fast" . IMO, he is spewing a shear heresy. The equations cited in this paper http://jullio.pe.kr/fluent6.1/help/html/ug/node245.htm show the only time dependent element,http://jullio.pe.kr/fluent6.1/help/html/ug/img1016.gif=fluid mass flow rate (kg/s), is in the numerator, hence the heat flux q increases proportionally with fluid mass flow rate. In another words, bigger the pump trough-put results in a higher heat transfer and efficiency. http://jullio.pe.kr/fluent6.1/help/html/ug/img1024.gif The same is true for the heat transfer coefficient, http://jullio.pe.kr/fluent6.1/help/html/ug/img1026.gif, http://jullio.pe.kr/fluent6.1/help/html/ug/img1027.gif |
Originally Posted by TeeJayDubya
(Post 7365629)
Faster flowing coolant will always have a larger delta T between it and air in a liquid to air HE, especially toward the coolant exiting end of the HE. Q is always greater with a larger delta T. Therefor faster flow enables more cooling of the coolant in the HE. Some things are not necessarily intuitive to us (or your friend) and thermodynamics sometimes falls into that category!
The below could be flipped and + repeated for the front HX at the grill = 10 components in total = somewhat complicated - although it is a simple "series" calc (apart from the fact that the Garrett IC on my SLK32 is a 3 pass counter current unit). Some guys are making it single pass and claiming benefits due to higher velocity = higher reynolds# = lower boundary layer thickness/resistance, but I've never seen anything definitive. If it was better, Garrett would have done a single pass in the first place as it would make manufacturing much easier and keep costs down. https://cimg4.ibsrv.net/gimg/www.mbw...97c7e0dee7.jpg |
https://cimg7.ibsrv.net/gimg/www.mbw...0c459eebe0.jpg
https://cimg8.ibsrv.net/gimg/www.mbw...2ba564fbf0.jpg Hello, I need two CWA50 at the decent price. I even take one used, so if you have any spares on the pile - gimme a jingle, please. I'm trying to upgrade mymy Lotus Esprit S4s charge cooling system In US, demand went up exponentially due to CWA50 use on Mustang GT500. I have searched Ford PN#DR3Z-8501-A , but prices are ridiculous. I think, the same pump is used on BMW-s, Pierburg W0133-1848269 . Is this the right PN# ? Any pointers??? specs: https://www.scribd.com/document/3117...0-coolant-pump How to install instructions: http://www.departmentofboost.com/PDF...tions_S197.pdf |
PM me for new Pierburg CWA-100. I get them heavily discounted including the mounting brackets. |
https://cimg5.ibsrv.net/gimg/www.mbw...4ad813dbbd.jpg
I'm wondering how to control CWA50 pump via PWM terminal without acquiring Tecomotive module. BTW, anyone peeked inside of it? What's there? Reverse engineering is required, IMHO. For 100% speed, I found this diagram, attached. Is it correct? |
Just connect fused power to the +12V pin and ignition to the PWM pin.
The resistor is optional. It's not required, but it's good protection. Nick |
Tecomotive controller for CWA50?
Nick,
In the post #43 you've said:
Originally Posted by Welwynnick
(Post 5666260)
Thanks for bearing with me; this is where it starts to get interesting.
I contacted Tecomotive, the manufacturer of the tinyCWA Pierburg cooling pump controller. Like the Davies Craig pump controller, theirs is designed for engine cooling, so the temp range is appropriate for that application - 75 to 100 deg C. So I asked Tobias Mucke at Tecomotive if they could modifiy their controller to work over a temp range more appropriate for a low temp charge cooler system. And guess what - they said yes! The knob on the controller sets the mode - essentially the target temperature - and the LED display gives an indication of the actual temperature, or the actual pump speed - whichever you chose to display. The displayed temp range is also customized to match the charge cooler target temp range. Its really a very clever little box; so many tunes to play. Its a new derivative called the Charge Cooler Special, and there's a revised user manual that I could send to anyone interested. And I've got the first one! Nick :) Thank you John |
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John |
Amazing thread...I applaud you @Welwynnick
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Big fan of some of the discussion going on here circular or not this issue has been around for some time and it is always interesting to see if there are any new ideas. I've seen many folks recommending going with a single pass intercooler but has anyone considered doing a dual pass conversion with a better core like from Bell Intercoolers: https://bellintercoolers.com/ ? Another question I had was if anyone has had any luck running the MBH monster heat exchanger in conjunction with say a PLM XL or Eurocharged heat exchanger. Would the CW100 pump be able to handle all of that?
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I just bought used CWA100 and I decided to try it on the bench before installing. I connected pin 3,4 to +12v and pin 1 to negative lug of the battery.
Well...nothing happened. Are these pumps equipped with a sensor preventing pump from spinning when there is no coolant present inside? Thank you |
Originally Posted by MrDangerUS
(Post 7960247)
I just bought used CWA100 and I decided to try it on the bench before installing. I connected pin 3,4 to +12v and pin 1 to negative lug of the battery.
Well...nothing happened. Are these pumps equipped with a sensor preventing pump from spinning when there is no coolant present inside? Thank you |
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