water flow across charge cooler core

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
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cantfindausername
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water flow across charge cooler core

Post by cantfindausername »

As I'm needing to plumb in my charge cooler ini the very near future, I've starting to wonder what way I should plumb it in.

Basically the water passes over one core, loops round and comes out over the other core.

So my question is, should the water enter on the first core (turbo side), or the second core (throttle body side)?

This is the unit...

Image

Thanks,
Ant
Guy Croft
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Post by Guy Croft »

Ant, hi

I would not wish to stand in the way of a perfectly relevant thread but doesn't the manufacturer tell you this? If not why not?

GC
cantfindausername
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Post by cantfindausername »

Hey Guy, Its a custom unit that I bought from a friend in Holland when his plans changed.

I've done a bit of digging around the net and one theory I've come across is that the cooler water should cool the cooler air, and the warmer water should cool the hotter air.

I think I can see the reason behind this though, because the colder water will have a greater impact on the slightly cooled air than if it was cooling the hotter air. Thats my current thought lines anyway.

Still digging for info though.

Ant
Evodelta

Post by Evodelta »

Hi Ant,

What you have found out is correct and there is no other way to do it, the water flows in at the cooler end (throttle) of the chargecooler and then onto the hot (turbo) end. This is known as 'Countercurrent'. Take a look here:
http://en.wikipedia.org/wiki/Heat_exchanger

And here:
http://en.wikipedia.org/wiki/Countercurrent_exchange

For a fuller explanation.

It looks like a nice piece of kit and the way it has been designed (to take advantage of countercurrent flow) shows that the someone has given it some thought.

Hope you don't mind answering a few questions for me as chargecooling (air or water) is a subject I am particularly interested in; What are you going to use the car for and what dimensions does the core have (section and tube length?

Martin.
cantfindausername
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Post by cantfindausername »

Hi Martin,

thanks for posting those links for me, I'll be sure to give them a read in a short while.

The car is going to be used for all sorts of things. I will be doing some 1/4 mile runs, and some cross european rallies. I will also at some point be doing some track days. So I will try its hand at most things.


I can measure up the cores for you no problem. Just one thing though... I'm not sure what you mean by tube length? Is this part of the core? Forgive me as I'm still quite new to this area of my build.

thank you,
Ant
Evodelta

Post by Evodelta »

Hi Ant,

The tube length is shown below in red and is the path the charge air travels down whilst being cooled, the section (width and thickness) is shown in blue.

If you can find the time, a pic down the inlet pipe of the core would be excellent too!

Thanks,
Martin.
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SteveNZ

Post by SteveNZ »

The intercooler does not offer true countercurrent flow as the service fluid is travelling at 90 degrees to the flow channels (tubes). At best its a 2 stage system. I doubt it will make much difference but connecting it as you say should be better in theory.
Guy Croft
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Post by Guy Croft »

I don't see the point of this cooler, Ant, sorry. Engine coolant temp 75deg C, borderline knock air inet temp 45 degC, what is it going to achieve? You'll detonate your engine with this unit.

You need to have a careful reappraisal of what's happening here before fitting, no matter how nice it looks. Unless you're going to run iced water through it, it is not going to do the job. Use an air-air cooler. At least with a finned matrix chargecooler you can spray water on it to bring the temp down via a throttle microswitch if you have to.

Here, plumbing to the engine coolant circuit, well, you're wasting your time. OK for oil cooling (oil 90 +), but for intercooling? Forget it. You need to ask why the previous owner ditched this piece of fabrication art really...

GC
Evodelta

Post by Evodelta »

Guy,

Modern chargecoolers don't use engine water to cool, they have their own dedicated system including a seperate radiator and pump, some older trucks use the system you are refering to. Properly designed CCs are very efficient, especially when used on road and drag cars.

If I remember correctly Ant has an Mr2, rear engined turbo cars and CCs were made for each other as the best place for an intercooler is at the front of the car, this is no good when the engine is at the rear....

As a rough rule of thumb:
Hillclimb, sprint and drag use - Chargecooling is good, either are used.
Circuit, rally - intercooling is better, chargecooling is rarely employed.

Road cars can use either successfully.

How efficient your CC system is is largely dependant on the cooler itself, but also VERY important is the size of the pre-rad, the amount of water in the system and the pump flow rate, you can of course bend the above rules by adapting your system to the required use.

Hope this helps,

Martin
cantfindausername
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Post by cantfindausername »

As Martin said, this will have its own pre-rad, pump, header tank, and dedicated water lines.

The radiator that I'm using is from a Fiat Cinqucento. This radiator is used on ~95% of MR2 installations.
Toyota actually made its own charge cooler system which was fitted to the Celica GT4 (WRC). It was never fitted to MR2s from the factory, but the Toyota system has been sucessfully adapted by many MR2 owners in recent years.

The pump I'm using is a Davies Craig (EBP) Booster Pump which has flow rate of ~13.3L/min. Again this pump has been tried and tested on many applications of high powered MR2s.

The water system should be a fair size. I'm using 19mm hose, and intend to fit a SPAL fan to the radiator to help when it traffic when there is little air flow.

If the system doesn't produce the required results for any reason, then I will be swapping to a boot mounted (air-to-air) intercooler.

Martin - I'll do my best to get some pictures from inside the core later today when I'm at home.

Ant
Guy Croft
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Post by Guy Croft »

Ant, hi

thanks for briefing me on the layout.

GC
cantfindausername
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Post by cantfindausername »

No worries Guy. I probaly should have put more detail in at the start to save from any confusion. Got there in the end though at least.

Ant
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