Charge cooler water flow rates

[Turbo-Brown]

So what do we think, is there an arguement for getting a pump which flows water around like nobody's business (say 230l/min) or do we reckon that something which does just 50l/min would suffice.

Seems the pumps have a fairly finite life expectancy if they're running continuously, around 700 hours or so. That said, at an average speed of 30mph, that's still 21000 miles so I guess they should last a few years.

I've been thinking of using a marine bilge pump as they're cheap and plentiful, they're also submersible so I could just install one in the bottom of the tank and forget about it for a couple of years.

Whadda people reckon?

[Gunni]

Wouldn´t you need to do a test to see what´s actually needed,
to much flow and you don´t get as good heat exchange vs. voltage and electric power spent.

[mattG]

Subaru's Legacy GT MK1 had liquid intercoolers could you find there specs?, it was quite a small unit/rad sitting on top of the engine.

[glenn]

Subaru's Legacy GT MK1 had liquid intercoolers could you find there specs?, it was quite a small unit/rad sitting on top of the engine.

my brother has recently bought a lotus esprit turbo which is
charge-cooled, i'll see if he has any info on flow rates for the water/pump

[Turbo-Brown]

Cheers for the replies chaps

My thought is that if the flow through the heat exchanger is quick, every unit of water will increase in temperature less than if the flow rate was low. I also reckon that if I fit a great big rad at the front through which the water will flow slowly, it will have lots of time to reject heat before reaching the cooler unit.

I'm also of the opinion that the faster the water travels through the cooler, the more even the temperature will be comparing the water inlet to outlet.

Certainly be interested to know what kind of flow fate Lotus used!

For a 230l/min pump, I'm looking at something in the region of 140W, which is only about 0.2hp

[appletree]

Another major manufacturer to use charge cooling on a car was jaguar with is supercharged V8, might be worth looking in to!

also think about the resitance through all your pipe work! a bilge pump if its like the ones i'am thinking of is not positive displacement so you could end up with in not being able to make enough pressure to force the water through the system. after all there only suposed to pump a metre or so.

i used a 12.5ltr per min positive displacement pump on mine and that works well but did get very hot which is why i'am gonna swop to a twin pump set up (probly bigger pumps to as i'am there) and run one before the cores and one before the cooling rads.

like you said with the heating and cooling of the water, if you can keep the differents in temps as high as posible then its easyer for the fast flowing cool water to take a few degrees off the core than slow flowing water slowly trying to get the core to ambeinet.

my charge cooler water runs at around 18-21degrees depending on the day and takes 70degree(after S/C) air down to 40degrees(inlet)

might be worth looking in to wether the pump can handle anti-freeze or something like wetter water?? dont think mine does

[Turbo-Brown]

Some interesting things to think about there Matt

Think some of the pumps I've been looking at can lift to 5m! so the engine being about 60mm tall shouldn't represent a problem.

Also, for every unit of water which goes up, a unit will go down and in a sealed system that should mean the pump isn't really having to do a lift, so that just leaves drag through the cores which I wouldn't think would be a problem.

Tis a good point about the anti-freeze though! I'm hoping that if they can live in salty salty sea water then they can cope with pretty much anything....unless the anti-freeze attacks the seals.

I reckon that going for the submersible pump should mean that the pump itself can reject heat into the water.

Did you rig yours so that it pumps from the resevoir, through the rad at the front, up to the cooler and then back to the resevoir? That's what I had in mind, with a small header tank to make sure everything stays full and bubble free.

[jkarran]

Especially with a roadgoing turbo setup which produces heat in short bursts your water in the charge cooler is basically just thermal mass. Water has a very high specific heat capacity, in excess of pretty much anything else you might use to absorb heat (except amonia IIRC) making it ideal. All you really need is to ensure that the water is circulating fast enough that you don't get too much heat build-up in the chargecooler. basically make sure the IC is recharged with cool water between normal big squirts on the throttle, eg accelerating between bends or overtaking a row of cars. For road use you can achieve this quite simply by having lots of water, the rad needn't be too big since it's not dissipating heat much of the time on the road.

For blowers and track use where you're on boost (generating heat) for a large proportion of the time you do need to be able to shed heat as fast as you're generating it. Adding water wont help significantly, it'll just delay the onset of heatsoak and IC inefficiency. In this case a huge rad is essential.

For a heavyweight (roadgoing tin top) road car I'd just add a decent mass of water (which you'll have with the large cossie core + a rad) and pick a pump that will withstand continuous opperation. Submerged pumps have the benefit of being water cooled by default. In a very lightweight car there's something to be said for more heat dissipation capacity and less weight.

jk

[Turbo-Brown]

Don't think it would hurt to have a fairly large rad though would it? It'd contribute to the mass of water and also make absolutely sure that the water entering the cooler is as cold as it can be.

One thing which did occur to me was that if I drive around for a while and then switch off, all the water in the cooler is going to get quite hot as it'll just be sitting there So having a nice big rad should help to quickly bring the temp of the water down again once the engine's started again.....or so I'd hope.

[jkarran]

Nothing wrong with a big rad apart from cost, weight and space. As those are probably both small considerations in an E30 it makes a lot more sense to have a big rad instead of a big header tank and a small rad.

It'll all mix and come to an even warm state pretty rapidly after re-starting rather than having all the hot water atop the engine.

jk

[mattG]

How efficient is the water to air over an air to air intercooler chaps?

[appletree]

As for the order of mine it goes...

Resivour (e30 washer jet tank 3ltrs?)>Pump(sat in old battery try, so no head of water)>cores(water fed from either end)>coolers(one in oil cooler space and one behind the front grills)

This set up ensures that theres the maximum differents in temp between the water and the air its trying to pass its heat to, as your probly aware the enishel heat trasfer will happen quickly but will tail off as the two temperatures start to become even. This also means that the hot water isnt then coming back in to you cool resivour and heating up that, also in the position mine is while the waters in resivour is loosing heat to the passing air that comes through the gap behind the head lights.

[Turbo-Brown]

Sounds like we only differ with the location of the rad in the system.

My thinking was that my tank will be sat beside the engine where it's likely to get warmish. I want to keep it low down as it will weigh a few kgs.

Because of the warmth issue, I was thinking: run the water through the rad and then take the freshly cooled water straight to the cooler. Then the warmed water can fall back the the tank ready to go round again.

Would certainly be interested to know what Jag and co have done.

Heat soak when the engine's off can't be too much of an issue if Jag and Lotus site the coolers on top of the engine I guess

[e30_Turbo]

Alex,

A friend uses a CC on his 325i turbo, the main rad is positioned in the front valance, it's as long and wide as the stock rad but only half the height. The header tank is positioned on the inner wing with the pump and the CC is a very small unit that's not much bigger than the stock AFM.

When I'm there again I'll get some pics as it's a nice little setup which a mate of his made up for him from ally.

He also uses a IC aswell but it's only a fraction of the size you would expect and sits behind the CC rad and infront of the normal rad so I doubt it does much anyway.

It was just such change to see a setup actually working, he RR'd to 350bhp and over 400ftlb so it does work!

HTH, Mark.

[Geoff]

So what do we think, is there an arguement for getting a pump which flows water around like nobody's business (say 230l/min) or do we reckon that something which does just 50l/min would suffice.

Seems the pumps have a fairly finite life expectancy if they're running continuously, around 700 hours or so. That said, at an average speed of 30mph, that's still 21000 miles so I guess they should last a few years.

I've been thinking of using a marine bilge pump as they're cheap and plentiful, they're also submersible so I could just install one in the bottom of the tank and forget about it for a couple of years.

Whadda people reckon?

If you have a high flow water pump, does that mean you need a high flow thermostat? If it does have you considered using a balanced thermostat?

I have heard thermostats can be off as by as much as 10 to 20 degrees F in regard to their stated opening and closing points. My dad tells me balanced styles are normally accurate to within 2 degrees.

The balanced version has whats known as a "wax pill" which is designed to melt at a certain point, opening the thermostat at precisely the same temperature every time. It has a 3-port construction that equalizes the water pressure from above the valve (radiator side) allowing pressure on both sides of the valve rather than just one as normal. This allows the thermostat to open and accurately no matter what the water flow, pressure, or engine RPM is at that particular time.

Just a thought.

[appletree]

Turbo Brown
Matts Dad here in my oppinion the resevoir needs to be storing cooled water, the reason for having a res' in the first place is to act as a buffer under peak conditions, if you are storing warm water much of the value will be lost. If you disipation rad is large enough to cool the stored water, you don't need a resevoir in the first place.

[Turbo-Brown]

Hey Matt's dad, how's it going? Hadn't thought of it like that. In light of that, I guess a tank which just houses the pump and prevents it from running dry, a large rad and then the cooler would be the way forward.

Guess if the rad's large enough then it'll hold enough nice cold water to act as the buffer in it's own right.

I have to admit I'm surprised at how effectively Matt's setup works! Is the air forced to pass through the fins on the cooling bars or does it have the option to pass around?

Either way, I'm quite excited by the potential of the Cossie IC core to cool the charge air!

[appletree]

Matts Dad again
All the air is forced round the fins, the two cores sit side by side with a U shaped box wrapped round them, there are 2 longditudal slots in the face (not quite true as there is a bridge piece) one third the width of each core oposite the centre of each core so that the air flow splits 4 ways giving the maximum contact time/surface area. Matt could have completed the box by wrapping the box round the downstream side of the cores,but he didn't LOL

I suppose regarding cooling and thermal mass etc, its all a compromise, if its for road use then duty cycle says it will probably be ok as in the ratio of on boost time to off boost time allows the system to catch up. If for very heavy use (track) then the system needs to be much more efficient to be effective. The overall problem is that the return water from the laminovas is not all that hot and thus the differential temperature coolant to ambient is small, the smaller the diff temp the larger disipation rad is required' on the plus side water has a large thermal capacity and as such is able to absorb a lot of thermal energy for only a small increase in temp.
Hope this helps, as they say a picture speaks a thousand word, and if I had one i'd show you it. I think there may be one on matts thread I'll check.

[appletree]

Turbo brown try this if I've done it right page 15
http://www.e30zone.net/modules.php?name ... highlight=
Matts Dad

[Demlotcrew]

So what do we think, is there an arguement for getting a pump which flows water around like nobody's business (say 230l/min) or do we reckon that something which does just 50l/min would suffice.

Seems the pumps have a fairly finite life expectancy if they're running continuously, around 700 hours or so. That said, at an average speed of 30mph, that's still 21000 miles so I guess they should last a few years.

I've been thinking of using a marine bilge pump as they're cheap and plentiful, they're also submersible so I could just install one in the bottom of the tank and forget about it for a couple of years.

Whadda people reckon?

If you have a high flow water pump, does that mean you need a high flow thermostat? If it does have you considered using a balanced thermostat?

I have heard thermostats can be off as by as much as 10 to 20 degrees F in regard to their stated opening and closing points. My dad tells me balanced styles are normally accurate to within 2 degrees.

The balanced version has whats known as a "wax pill" which is designed to melt at a certain point, opening the thermostat at precisely the same temperature every time. It has a 3-port construction that equalizes the water pressure from above the valve (radiator side) allowing pressure on both sides of the valve rather than just one as normal. This allows the thermostat to open and accurately no matter what the water flow, pressure, or engine RPM is at that particular time.

Just a thought.

IF you have an electric pump you would just ditch the thermostat