Is there a potential pressure build up issue with increasing restriction?

 

Yes, this will also work, and is an easier and probably better way to go. A 12-volt rheostat that is rated to handle the current draw of the motor should do the trick.

 

As you close the flow valve, pressure will increase between the pump and the valve. However, the amount of restriction needed to decrease the flow a small amount should not cause an appreciable pressure rise.

 

I'm glad there is a simpler, electronic solution because i had a look behind the grille where the pump is mounted and the lines are in an awkward position to be able to fit that valve on there.

This rheostat sounds like a simple solution to implement and test.

 

I have played with controlling flow rate via voltage, however there were no pros nor cons.

If all of the lines going to and from intercooler core and intercooler radiator were increased to match the pump (1.5'' vs. 0.875'') than some ability to control the flow would be needed.

Ultimately we are limited by flow capacity of the core and to some extend of the heat exchanger.

The main reason I went with bigger pump was due to an additional heat exchanger that created an extra flow restriction. Majority of cooling gains come from an extra fluid capacity and an additional cooler, not from being able to push fluid quicker through the core.

 

Any possibility on a group buy potential for the IC pump?

Thanks

 

Another idea if you want to gauge whether the pump is pumping too fast or too slow, can always install a separate water temp gauge meter before and after the heat exchanger, the temp. difference. SPA Technique makes a dual digital temperature gauge IIRC, could be useful on the road, race, and dyno to see if the heat exchanger is working efficiently or if the intercooler pump just suddenly dies one day.

 

SPA Technique:

http://www.spatechnique.com/dualgauges/dualgauges.htm

#DG210B - Temperature / Temperate

 

Can anyone give me any additional info. on the "upgraded stock pump" referenced in this post? Any idea when these became available? Did MB start using the "upgraded" pump in production 55s as some point? (My car is an 05) I don't think I need a full aftermarket cooling system like EVO or Renntech, but I already have a PTE thermostat and a 10* fan mod, and I would like to know a bit more about any upgraded "factory" IC pump. Especially if the dealership will install one on a recall or "campaign" basis. Thanks!!

 

It is under a campaign. Comes from SC shut off. It was integrated into the '06 models. I do not know the technical stats differences.

 

How good is the pump from the MB campaign in comparison to the Johnson pump? Installing the pump is easy so I don't mind doing the Johnson pump myself if it is a lot better.

thanks

 

Question for Gumpy666

Your advice is tip top and I know I don't understand our cars like you do. So this is quite possibly way off...but in the case of this restriction idea I don't see it working the way you say.

..so apologies in advance if maybe I just don't understand the system (and I certainly might not).

Grumpy you say that too high a flow rate will remove the water from the IC faster resulting in higher temp water "reintroduced" into the S/C heat exchanger. This sounds right but....its the volume of heat removed we must look at to see if the S/C will drop in temp with different restrictions (wide open or less).

If the S/C is producing heat (!) then having a faster flow is only going to more equalize the temp diff from the exchanger in the S/C to the IC isn't it?

Although it feels as if you are having less time in the IC for any particular volume of water you picture in your mind's eye, in fact there is continuous flow and more heat is moved to the IC from the exchanger by the greater flow.

So long as the flow is continuous; moving greater flow means having less differential between the two (source and sink) and that could mean higher temps in the water itself but ought to mean better heat loss of S/C to the atmosphere overal.

Unrestricted high flow will rise the temp IN THE IC but still lose more heat as the S/C sees it (remember also Newton's law of cooling says that a higher temp in the IC will remove more heat to ambient even faster).

Ask yourself this question - How else can any mod cool the S/C more if it doesn't rasie the IC temp? And therefore the return water WILL be higher temp if we are cooling the S/C more.

Finally this might make it clear, image the S/C and IC directly connected by a 100% efficient heat "pipe" then the IC would go up in temp but we'd have the best possible cooling of the S/C to ambient - AND the pipe itself would go UP in temp....for us the water and the flow of it are that pipe.

What do you think? am I missing something?

 

Not trying to step on Grumpy's toes, but I would like to comment.

There is a tradeoff between the flow and time required to reduce the temperature. The tradeoff becomes less with an increase in radiator (intercooler) efficiency.

Believe me, a car without a thermostat (less flow restriction) can still overheat.

 

You make two points - taking them in order

First there is such a trade off but only if you are considering the WATER temp. But our goal is not reducing its temp...As I said this should (must) go up if we are taking more heat out of the S/C charge but have left the radiator the same. The point is trying to cool the water before returning by restrictions just stops more water from leaving the S/C in the first place (closed loop). Consider the heat in the Air charge not the water.

2nd point - Yes of course a car without thermostat can overheat, but that same car with the thermostat active (active meaning making some kind of restricted flow - which is usually referred to as a closed thermostat) overheats more quickly...
A wide open flow must reduce the heat the most - the temp of the coolant CAN go up as this happens. Again trying to reduce the coolant temp is not the objective.

In fact this illustrates exactly why we fit thermostats...if you have ever had one stick open you'll know your engine never heats up properly, only by restricting the flow (thermostat closed) can the engine heat enough to reach a good operating temp, then the thermostat opens and can handle the heat by keeping the engine temp at a warmed up operating temp. without OVER heating.
(This shows the unrestricted flow has sufficient removal to handle the entire heat produced...the restricted flow did not, that is why the temp of the engine increased to operating as desired).

Naturally a faster flow rate AND a larger radiator (and heat exhchanger if possible) are the right ideas for removing heat from the air charge we all can see that. But trying to control the water temp is not the right "view" on the problem. Now there are limits - if we heat the water/coolant beyond boiling point we'd be in trouble. But this bad state is even more likely with restriction than without.

I believe any restriction must increase the temp in the S/C compared to none exactly like a thermostat being closed while the car warms up.

 

is the aftermarket pump works better than the 06 upgrades stock i/c pump ?

 

You are, in fact, trying to reduce the water temp, as the rate of thermal transfer is dependent on the difference in temp from hot to cold (delta T).

Time is another factor. Reduce the time, you reduce the thermal transfer.

 

Yes the rate of heat flow is proportional to the diff in temp (I say that too) but trying to make the entrance water cold is good if it came from an infinite source (not a closed system) because your means of making it colder is to stop some other water leaving the hot region. Its simpler and better to continuously pump as fast as possible IF max. heat extraction is the goal (and here it is) rather than temperature control as a goal (like in the thermostat example) then pump as fast as possible.

But not in a closed recirculation system - all water "removed too soon" is immediately replaced with more - so imagining the water not picking up (or dropping off) enough heat because it moves too fast is not realistic. If we only had a fixed amount of water to collect the heat with - then the water ought to enter as low as possible in temp and leave as high as possible. But in continuous flow systems, we want more mass to continually carry away heat = high flow rate continuously.
Again if the system were 100% efficient it would be at the exact same temp as the S/C itself, moving ALL heat at the same temp to the outside radiator.
And IF the radiator was 100% efficient the water would enter it at S/C temp (above) and leave at ambient temp.
Restricting the flow to "make more time for the radiator to work" in an attempt to increase its efficiency, unfortunately penalizes the flow rate leaving more heat in the S/C exactly where we do not want it, and nothing is 100% efficient so doing this costs us in heat removal.

Its better to get the heat out AND radiate it off together not sacrifice one for the other....just get more flow AND a better radiator.

 

You cant just continuously pump water as fast as you want though. Remember the pump makes heat, friction from the water moving makes heat, and compression makes heat.

 

Dan,
Yes you can...why not ?

1) The heat from friction in the pump is negligible compared to the heat in the S/C (estimate less than 1%)

2) The water does not (in fact cannot) compress and so it doesn't heat from that. Gases compress, solids and liquids don't (otherwise hydrolic brakes wouldn't work).

 

Hey Vic...so if you bought the johnson pump, would it be the equivalent to buyin the cooling upgrade or will the results even be somewhere around the cooling package benefits? Do we also need to be another smaller "intercooler" along with the pump or will the pump itself suffice? TIA...

 

Right. Replace the word compression with pressure.

I understand your point and why you want to just flow the water as fast as possible, but I think you're overlooking a couple of variables.

I think you're underestimating the amount of heat the pump produces. I've installed external racing fuel pumps that pumped fuel too fast when driven on the street. During times of low consumption, if we ran the pump at full speed, we'd eventually boil the fuel and get vapor locked. Thats what fuel pump controllers are for, to step down voltage and slow down the pump. While running, an electric fuel pump is too hot to touch. An electric water pump is a very similar pump.

Also, the cooler lines are pretty small. Without enlarging the size of the lines, the only way to flow more volume is to increase the flow speed. If the water travels too fast, the amount of friction it creates will be significant. When we design turbo systems, we have to select charge pipes with the correct diameter so that the air speeds stay within a certain range. Anything more than 400 FPS air speed and it becomes inefficient. Its just inefficient to flow water through a heat exchanger three times before it releases its heat when you can just slow down the flow and do it in one pass.

I haven't actually tested water flow, so I guess the only way to know for sure is to do some actual tests. But if I were choosing an intercooler pump today, I'd personally choose one that flows the right amount and not just the biggest one available.

 

Well Dan - now I feel like I am over defending the idea and its a dead horse - lets just say your last paragraph is the important one.

The pump uses 12v at 6 A = 72W (picture a light bulb) hardly that high (and thats if all the energy went to friction/heat). When fuel is not moving or mving with a big restriction (!) even 72W will boil it eventually sure.

Water (or really coolant) isn't aircharge and frankly we would have to do experiments to find out the real situation. But friction is (for me and admittedly without measurement) not significant compared to a S/C that swallows almost 100 HP when wide open. (And you are knowledgable so I know you can picture that as some engines entire output)

well until some one does the experiment we won't know for sure...