Thread: Air 2 Water Heat Exchangers

Hi Guys,

this thread is really interesting, especially for those like me, that are trying to decide which set up is the best.
I am rebuilding my GTI-R : The block has been built by Mazworx and is based on a TOMEI 91mm stroke crank, CP 89mm pistons, Darton Sleeves, Manley turbo tuff rods.
The head has been gas flowed and polished and will use 272° Jun cams, springs,retainers and gears.
I will run a GT35 turbocharger and I am looking for 550 hp. Now the point is that I really need to cool down the inlet temps as much as possible. Tried to find suggestions/experiences on the net but haven’t been lucky…the result is increased confusion!
Basically I have to decide between two options:

-Front mounted PWR intercooler with a core size of 600x300x73mm
-Air to water intercooler with a 600x300x50mm front mounted water radiator, PWR 6x10 Barrell intercooler and Meziere water pump, with 12AN water lines and of course a water tank.

Both systems will be assisted by a water injection kit, that in my opinion is a great help in reducing inlet temps and removing hot spots from the combustion chamber.

Now the point is….which one would work better? Who knows?

Water to air will be more efficient for sure if I use ice, but I don’t want to use ice as it is for a road car and ice will melt before the end of the trip.
W/A 50mm thick radiator will allow more air flow to the radiator only If I do not use fans, otherwise the fans will act like a barrier, just like a deep front mounted intercooler, if not worse.
I also looked on ARE cooling web site and there is a nice description on water to air intercoolers, and it seems that is not that much more efficient compared to a air to air unit.
Air to air units rely on air to cool the charge, therefore the inlet temps will be close to ambient temp (assuming a good turbo and core efficiency). Ok we all know that water is far superior in absorbing heat, but at the end of the story the water will always be cooled by the same air that cools the front mounted intercooler, so I don’t see much difference.
On a A/A system, there is only one exchange, while on a W/A the cooling is done in 2 different steps: Charge air cooled by water and water cooled by air.
Both PWR and BELL intrercoolers state that because of the 2 heat barriers the efficiency will be lower.
For sure W/A can give more constant inlet temps, but after a little traffic and if the water gets too hot it will take more time to be cooled down. Seem that water can absorb much more heat, but it also stores the heat longer.
Then there is price. I have sourced a company that can custom built the water radiator for around 100 $ from China, plus around 200$ for all braided hoses and hose ends, plus around 200$ for the Meziere water pump and around 700$ for the PWR barrel
I know that there are cheaper units around, but we do not want to cut corners here as a leaky water to air intercooler can cause big damage on the engine…no water in the engine !
While a PWR A/A intercooler is around 500$ and is for sure less complex.
Then there is to consider that a lot of high power car are using A/A intercoolers…if W/A is so much better, why it is not so widely used? One reason could be for cost, but cost should be an issue when tuning a 1000 HP skyline…
Water to air must be done right, with large radiator and large water tank and a good pump to move the fluid .Done in that way I am confident it will work great . Maybe there is a lot of confusion because a lot of installation I have seen we based on small radiators and cheap itercoolers…

Opinions anyone?

It is a cost issue for most people. But, there are MUCH cehaper options than the PWR units. In my experience, they are only nice for fitment factor, other than that I like the regular rectangular style cores over the PWR.

If you run a large core with large lines and a decent size cooler, it will not heat soak like people are saying it will. OF course there will be increases in water temp, but water can pull 4 times the heat out of the charge air than an air to air unit. So, for the same period of time the charge air is going through, water is pulling out 4 times as much heat. This is nice because it works at really low speeds (corners and so on) when air flow is really low across an air to air cooler. They were popular for rally because nothing was left exposed to debri and so on like the air to air were.

Brent

Thank you coach. I was wondering why they wanted over $800 for a PWR core when I can get a reg core good for 1000hp for $200.

I have talked to my domestic friends and they all say they have amazing results with air/water setups with roots blowers. The roots style is not the best for efficiency and yet they still cool the air down tons.

there are a lot of info on this web page.

AVT - Chargecoolers, Renault Turbo Tuning, Gauges, Charge cooling, Forged Pistons, Turbochargers

the explaination of water flow is really intresting to me