Thread: Dual intercooler set up

Originally Posted by Blknight.aus

A small air to coolant heat exchanger can be fitted in place of the pipe from the turbo to the intercooler.

I'm currently in the process of doing it to the wifes tdi which is just slightly tweaked.

Dave, please do share pics and details when you have finished this as I've often contemplated doing the same. Thanks

Originally Posted by Blknight.aus

care to explain that....

Sure. The water is your extra layer of insulation.

In an air/air exchanger you have:
Hot air/aluminium/cold air.

In an air/water exchanger you have:
Hot air/aluminium/water/aluminium/cold air.

Originally Posted by Dougal

Sure. The water is your extra layer of insulation.

In an air/air exchanger you have:
Hot air/aluminium/cold air.

In an air/water exchanger you have:
Hot air/aluminium/water/aluminium/cold air.

completely irrelevant to the point of cooling the charge air...

Its not an extra layer of insulation (if you want to run that in reality its 2 extra layers) its just an extra stage in the cooling process)

I'll put money on the air-coolant charge air cooler being much more effecient at getting heat out of the charge air. compared to the same size air-air cooler

Originally Posted by Blknight.aus

I'll put money on the air-coolant charge air cooler being much more effecient at getting heat out of the charge air. compared to the same size air-air cooler

Why would you do that? Can you explain your reasoning?

Heat exchangers have no efficiency because they have no energy conversion. All they are doing is conducting heat and water/air have a lot more thermal gradient to work against.

There is no more effective way to cool air than a large air/air exchanger. Water/air are of main benefit when you can't get large air pipes through.

his reason is water to air heat exchanges are much smaller then a air to air.
the main problem with water to air is they can only cool to engine coolant temp not below unless they have a separate cooling system.
from memory the cat c15 acert water to air (jwac as cat calls them) is not much bigger then an ream of a4 papper and is used to drop the intake temps from upto 200 degC to around a 100degC so the air to air inter-cooler can be effective.
Cat had to use a water to air setup to precool as they could not fit a large enough air to air to handle the job alone, but the water to air did not cool enough.

so they each have there place and it comes down to how much temp you need to remove but if your getting near ambient temp then with out introducing something for extra cooling you wont get any benefit from going larger or fitting both

I am not an expert but i think until the water is cold enough the Ait-toWater draws better the heat from the acharging air than the Air-toAir, but the hardest job is to keep the coolant cold enough.
Anyway very informative discussion, i follow with interest.

Originally Posted by lyonsy

his reason is water to air heat exchanges are much smaller then a air to air.
the main problem with water to air is they can only cool to engine coolant temp not below unless they have a separate cooling system.
from memory the cat c15 acert water to air (jwac as cat calls them) is not much bigger then an ream of a4 papper and is used to drop the intake temps from upto 200 degC to around a 100degC so the air to air inter-cooler can be effective.
Cat had to use a water to air setup to precool as they could not fit a large enough air to air to handle the job alone, but the water to air did not cool enough.

so they each have there place and it comes down to how much temp you need to remove but if your getting near ambient temp then with out introducing something for extra cooling you wont get any benefit from going larger or fitting both

The water/air heat exchanger can be more compact than an air/air. But it needs the same internal surface area if it wants to move the same amount of heat.
You can make water/air exchangers more cube shaped, where air/air have to be planar to get cooling air through them.

If only cooling to ~100C is the aim, then a very tiny air/air will do that job. But for an air/water to shift the same heat as an air/air it needs it's own water circuit and a water/air radiator out the front which is the same size or larger than an air/air cooler.

Very rarely does a water to air have its own coolng system they mostly run off the engine cooling which is why they only cool to 100 deg C f there at there most efficient
If fitting its own cooling system then a water to air will take up more room the a air to air which is why they are mostly used to precool for an air to air as the cat system does.