Understanding Intercooling, Charge-Coolers, Heat Exchangers and Circulation Pumps
Nick
Through 5/8" hose, I don't think the Meziere even performed as well as the original Bosch "cobra" pump I had.
I really don't know the answer. Slower pumping means the water arrives at the intercoolers cooler and leaves hotter, and that there is a larger temperature differential between water at various points in your system. Which should make the front mount heat exchanger more efficient, but the intercoolers might have a higher temp due to the water staying there longer (but it was possibly cooler water to start with). On the other hand, pumping it faster would keep your water temps more consistent throughout the system and no one point would be likely to heatsoak, which would ensure the intercoolers were receiving a more consistent water temp across the entire core. Would it depend more on what your total capacity as to which strategy makes more sense? I kind of think the flow is only important to the extent that the mass flow rate of water is enough to maintain a reasonable temperature rise from one end of the intercooler to the other, beyond that, more flow may just be crippling your heat exchanger capacity (which will always happen anyway the closer the water temps get to ambient).
What are your thoughts, and why?




Need to think of cooling in terms of power, not temperature, heat or energy.
See graph of Cadillac IC cooling performance early in the thread - cooling performance gets better as coolant flow increases - it never tops out.
LOTS and LOTS of good anecdotal evidence to support this, and nothing to contradict it, just supposition, no evidence anywhere.
Nick
What I really wonder about is to what degree the diminishing returns come into effect in say a 100% stock intercooler system with just a pump upgrade. Are you doubling the flow to net a 1% cooling improvement, or are you doubling the flow to net a 20% cooling improvement, etc? I simply don't know the answer to that, and thus don't know how far it is worth chasing. But make no mistake, I'm an enthusiast...I enjoy the chase, even if it's mostly to disproportionately expensive results. I still try to prioritize on somewhat of a cost-efficiency basis though.
The tricky thing with cooling systems is that the more effective they are, the less efficient they become, and vice versa (at least in terms of the front mount heat exchanger)...due to diminished temperature differential.
USA EMP pumps distributors locator : http://www.emp-corp.com/support/dist...or/default.asp
UK distributor : http://avidtp.com/products/pumps/wp29-epump/
Buy I also wrote a comment on youtube guy installed EMP pump on his mustang and this is what he said :
Mercedes-Benz & Cars and street racing3 days ago:
does this emp wp29 24v version works with 12volts?
Reply
Jamieson Allen
+Mercedes-Benz & Cars and street racing
Yes this works with 12 volts. Also you can have it flow at two different rates. When you order just specify which rate you want. You can send it back also to have them program a new rate too.
video link :
So as far as I understand giy buy 24v pumps and run it on 12v?
or may be just a common 12v to 24v converter would work for us?
I will get more answers on this from emp pump distributors wanna install this pump on my car so bad



I'm still like 99% sure you can't run the 24V pump properly on 12V. It would probably just have terrible performance. Chances are that guy has a 12V pump and didn't understand what you were asking. There are at least two different calibrations available on the pump that change the current limit and such, I believe that's what he was talking about.
The Best of Mercedes & AMG




Nick
Last edited by MB-CLS500; May 5, 2016 at 01:13 AM.
I still have quite a bit to do, but I think it will be done before the end of the weekend. Still need to install mount points for the ABC cooler and lines onto this radiator, and hopefully get the tanks modified for my intercooler lines. I'm super tempted to pull the tanks off and make custom aluminum ones. There's actually quite a bit of room I could make the tanks bigger to bump the system capacity a bit. But at this point, I kind of just want to get the car back on the road so I'll make due with the plastic tanks for now (unless they end up not holding water after the modifications).
I am also considering building a reservoir that would tuck right in that empty corner of the bumper there on the passenger side. I really think some extra capacity would do wonders for keeping temps down on longer WOT pulls (or especially at the track). I don't know if it's worth the trouble with the available space though. I need to throw the bumper cover back on and get some dimensions so I can see what kind of capacity it would add.




Nick
So basically, I'll be installing it killer chiller style, with valving to bypass the front mount heat exchanger if I'm wanting to run ice in the tank or operate strictly on the A/C chiller system. Ideally, the stock pump would continue to circulate water through the heat exchanger and brazed plate A/C condenser I will be adding, while the pump in the rear tank will continue to pump from the trunk mount tank through the intercoolers and the brazed plate A/C evaporator core. This will take some extra plumbing and some 3-way valves (probably manual for now, I don't really want to come up with the $600 or so it would take to do it electronically). I think it would take 3 valves to have complete flexibility with the system.
Theoretically, that will allow me to operate the system any of three ways. 1.) As a stock configuration with just a lot more system water capacity.
2.) As an ice box system by bypassing just the heat exchanger, keeping both pumps working on one loop.
3.) In chill mode as two completely separate loops. One for chilling coolant and supplying it to the intercoolers, and one as an ambient heat exchanger loop used to water-cool an auxiliary brazed-plate A/C condenser to enhance the performance of the chilled loop.
That would give me the opportunity to experiment with various setups to see what works best without having to change anything other than flipping some valves. I may well find out that the A/C setup works well enough that I won't need/want changeover valves. Or that it's more or less pointless and I should just stay in a stock-style heat exchange loop all the time. But regardless of what ends up working, this way I wouldn't necessarily have to change anything later.
And if it does turn out I'm wanting to switch modes frequently or from the cabin, I can invest in upgrading to electronic valves after I'm satisfied that it's a good investment. Unless somebody has a significantly cheaper option than the one KC offers. http://killerchiller.com/products/12...pass-valve-kit
So if you buy this one, pressure test it before you do anything else. http://www.ebay.com/itm/251991128911?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT




Oh well, if it doesn't seal up at least I don't have to worry about breaking the tanks getting them off if I'm going to be welding completely new tanks on.
One thing I did differently is I didn't trim the A/C brackets at the bottom, so there is a very slight tilt to the heat exchanger. This has one advantage, that I won't need to relocate the under-tray screws, they are completely behind the bottom of the heat exchanger. Also, after having to apply so much silicone/sealant to the tanks, the A/C brackets provide for a nice tight wedge fit between the condenser and the radiator mounting brackets (I did have to cut a small part of the driver's side mount out to allow the heat exchanger to sit down far enough). I am concerned that this might transmit additional vibration to the cabin, but the silicone should help a bit and I am going to add vibration damping (car audio) mats to every bit of metal I can get to while I'm in there. The other downside to not trimming the A/C brackets is that I did have to clearance the plastic shroud/duct around the oil cooler. The pieces where it snaps together stick back quite a ways and would have been very, very close to the core if not touching it (they certainly touched the cardboard).
For mounting the lines and ABC cooler, I used the ABC mounting point, and retained the two condenser mounts with homemade spacers. I couldn't find M6 bolts long enough, so I had to grind the head of smaller bolts down and press them into a piece of aluminum tubing and do the same with a nut on the other end. The other mount that was attached to the condenser core on the driver's side didn't look like it was going to fit/line up, so I just cut those mount points off the lines and slipped split rubber hose over them to prevent vibration damage to the core or the lines themselves or other nearby stuff. I'll have to take pics of that tomorrow so it will make more sense.
The 3/4" plastic barbs I epoxied into the end tanks made it more difficult to install/remove the core, but certainly not impossible. I have a 90-degree one facing down on the passenger side, and a straight barb on the driver's side. Basically, it puts the connections very close to where they were from the factory and I think I should have no trouble getting the factory hoses on there as opposed to running new ones. I did not have to cut the headlight brackets, but it would make installation/removal easier if I did.
I ran off and left the camera at home and my phone battery is dead so I'll have to remember to snap some pictures tomorrow before I (hopefully) start buttoning things up.
Despite vacuum-filling it (I didn't dig out the A/C vacuum pump, just used the shop air-powered venturi style so it was only probably a 60% vacuum), it still took over an hour of running the pump before I was getting nice clear bubble-free coolant out the intercooler ports. I built my bleed setup out of the stock cap (since I will be replacing it with a radiator cap and utilizing an expansion tank) and an empty gatorade bottle. Basically I drilled a hole in the middle of the cap and cut the bottom off of a gatorade bottle and then epoxied it to the radiator cap upside down. Removed the schrader valves in the intercoolers, clamped a pair of hoses on there routed to the gatorade bottle, hooked up a 13.8V power supply and just let the pump run. Watched it for about 20 minutes and it was still really cloudy so I decided to just go to dinner and keep letting it run. It was finally running clear (and a lot better flow) when I got back so I'm pretty sure I'm good to go. In retrospect, I wish I had put a bleed fittings in the top of the x3 radiator. I think it would have made the process go a lot faster. Next time I'll probably just rig up an adapter for the A/C vacuum pump...that thing will get ALL the air out.




Mercedes dealers use a compressed-air vacuum pump, and I think that's a compromise, too. You don't actually have to get a total vacuum to get all the air out, but you have to get it low enough to boil water. That's the vacuum equivalent to the saturated vapour pressure of water, at whatever your ambient temperature is.
Therefore you need about 99% vacuum (1 kPa), and then the coolant will boil, and after a while it will totally replace all the air in the cooling system with water vapour. Then, when you refill the system with coolant, the water vapour will condense back to water, and you have a totally, guaranteed, 100% air-free cooling system. Even in the parts of the HE and IC that you can't bleed.
Compressed air pumps only get down to around 80% vacuum, but single stage rotary vane pumps will go below 10 Pa without breaking a sweat. 1/4 hp Chinese pumps are less than $100, so it's almost a justifiable addition to a V12TT owner's tool box. Plus you can do your own AC.
It shouldn't have to be this hard, should it?
Nick
Mercedes dealers use a compressed-air vacuum pump, and I think that's a compromise, too. You don't actually have to get a total vacuum to get all the air out, but you have to get it low enough to boil water. That's the vacuum equivalent to the saturated vapour pressure of water, at whatever your ambient temperature is.
Therefore you need about 99% vacuum (1 kPa), and then the coolant will boil, and after a while it will totally replace all the air in the cooling system with water vapour. Then, when you refill the system with coolant, the water vapour will condense back to water, and you have a totally, guaranteed, 100% air-free cooling system. Even in the parts of the HE and IC that you can't bleed.
Compressed air pumps only get down to around 80% vacuum, but single stage rotary vane pumps will go below 10 Pa without breaking a sweat. 1/4 hp Chinese pumps are less than $100, so it's almost a justifiable addition to a V12TT owner's tool box. Plus you can do your own AC.
It shouldn't have to be this hard, should it?
Nick
After seeing that, I am definitely going to stop using shop air and the venturi deal to fill radiator/cooling systems as well. I definitely need to adapt the A/C vacuum pump to work with the fill manifold from that kit. The valving and all the fittings are really pretty slick, but even with 175psi shop air it's hard pressed to get above 70% or so vacuum. Which is a heck of a lot better than just pouring water in the filler for HOURS...but it would be nice to just suck it down, then switch the valves and know without a doubt it was going to fill properly the first try.
I am thinking something like the attached crude MS paint drawing. Basically, I will intercept the return line after the intercooler merge and install a 3-way valve at that point to direct the coolant through the heat exchanger normally, but through a bypass line Y'd in right at the stock pump inlet for when I have ice in the trunk tank. This will allow me to utilize series pumps as well as the full system capacity of coolant all the time, regardless of which operating mode I want to be in. It's just a simple blockage of flow through the heat exchanger when I switch the valve. It does not give me the capability to create two completely separate loops however, like I would need if I go to an A/C based setup. In the meantime, I think it's a good/cheap compromise. What do you guys think?





