# School me on Air to Water intercoolers



## Mr. Brown Pants (Aug 8, 2016)

School the noob on Air to Water intercooler setups. 

These look like a more affordable setup than a FMIC and less pipe work. Besides relocation of the battery in most cases why are these not a more popular option?

Those that have them where did your place your BOV, or DV? Or isnt one used?
How did you wire in the pump? Just a simple switch?

:beer:


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## Mk4VRSex (Jun 18, 2011)

It only seems simpler. A proper air water system takes some consideration. 

For street driving you have to have a heat exchanger and a properly sized one at that or you'll be battling heat soak. If you actually want to reap the benefits of air to water you'll also want an ice tank and those usually end up in the trunk. Now you have to plumb 3/4"+ lines from the back of the car to the front... so you've simplified the Intercooler piping slightly and added complexity elsewhere.


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## Mr. Brown Pants (Aug 8, 2016)

Mk4VRSex said:


> It only seems simpler. A proper air water system takes some consideration.
> 
> For street driving you have to have a heat exchanger and a properly sized one at that or you'll be battling heat soak. If you actually want to reap the benefits of air to water you'll also want an ice tank and those usually end up in the trunk. Now you have to plumb 3/4"+ lines from the back of the car to the front... so you've simplified the Intercooler piping slightly and added complexity elsewhere.


Are there cooling benefits vs a standard FMIC setup without the ice tank? or is it just plain simpler to run the FMIC? 

I totally get that it is a complex system, and there are well lots more failure points vs a FMIC setup. 

Anyone have an idea on how to size a heat exchanger (more or less a rad) for street driving?


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## Union Forge (Oct 10, 2014)

First off. There should definitely be a cooling advantage over an air to air setup even without an ice tank. That is as long as both your AWIC and heat exchanger are large enough. I would have an electric fan mounted on the heat exchanger if it were me. 

Second, not sure on what to tell you about size of the heat exchanger as I do not yet have any personal experience running an AWIC setup. I am currently doing research and piecing together a setup to be run on my MKII as we speak. However I feel that I could safely say that unless you are talking about some super high horsepower setup you would be safe with a heat exchanger half the size of your radiator, maybe even a little less. I would never suggest buying an EBAY company AWIC, but if you go online and look up the cheapy kits you will see the heat exchangers that they come with. The little ones I feel would not be large enough, except for the larger models they offer. 

Now as I said in the above, I do not have any personal experience or recorded results of my own. Only the knowledge I have gained from the research that I have done. So it would be really nice to see some test results from other peoples setups, such as specs (of the AWIC setup, and a run down of the motor and power output), intake charge temperatures (both before and after the AWIC), and even water temperatures (again previous to and after the heat exchanger in this case).


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## Mr. Brown Pants (Aug 8, 2016)

Union Forge said:


> First off. There should definitely be a cooling advantage over an air to air setup even without an ice tank. That is as long as both your AWIC and heat exchanger are large enough. I would have an electric fan mounted on the heat exchanger if it were me.
> 
> Second, not sure on what to tell you about size of the heat exchanger as I do not yet have any personal experience running an AWIC setup. I am currently doing research and piecing together a setup to be run on my MKII as we speak. However I feel that I could safely say that unless you are talking about some super high horsepower setup you would be safe with a heat exchanger half the size of your radiator, maybe even a little less. I would never suggest buying an EBAY company AWIC, but if you go online and look up the cheapy kits you will see the heat exchangers that they come with. The little ones I feel would not be large enough, except for the larger models they offer.
> 
> Now as I said in the above, I do not have any personal experience or recorded results of my own. Only the knowledge I have gained from the research that I have done. So it would be really nice to see some test results from other peoples setups, such as specs (of the AWIC setup, and a run down of the motor and power output), intake charge temperatures (both before and after the AWIC), and even water temperatures (again previous to and after the heat exchanger in this case).



I have to agree with you that there is not much information around on them. From a cost perspective their less in cost than a FMIC setup, have a shorter pipe run (helps spool), and give a "sleeper" look as the rad can be hidden with the a/c condenser removed (on a MK4 anyways). It does add complexity, and a new failure point. I fell that is off set by the potential gains. Frozen boost has a pretty good setup for about $350 I think once you upgrade the pump. There are a variety of things you can as well like water wetter, or coolant (ethyl glycol) to help absorb heat. 

I just don't know why its not more widely used. You can heat soak a FMIC still, the pipe run in most cases results in a pressure drop, and fitting the pipe work all in seems to be a bit of a headach. The wiring for the pump and fan would be simple and if running an 044 fuel pump or similar you could piggy back off that wiring so that it runs when the fuel pump is running. I feel like I am missing something here, there has to be a reason why its not more popular....


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## Butcher (Jan 31, 2001)

Water can absorb more heat than air. The intercooler could be made smaller and still be more effective. The water gets cooled by the intercooler and the heat exchanger when you are off boost so heat soak can be less. Proper coolant flow to transfer the heat is vital to a good system.


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## Mr. Brown Pants (Aug 8, 2016)

Butcher said:


> Water can absorb more heat than air. The intercooler could be made smaller and still be more effective. The water gets cooled by the intercooler and the heat exchanger when you are off boost so heat soak can be less. Proper coolant flow to transfer the heat is vital to a good system.


Good information to know :thumbup:

Anyone know why these are not popular?


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## Mk4VRSex (Jun 18, 2011)

Water is great at absorbing heat, that's the efficient part. Now remove heat from the water, that's the inefficient part. 

Proper coolant flow, proper sized heat exchanger.. this can all be achieved but you quickly learn air to water isn't simple and cheap as some think it is. 

I have a 900+hp compound turbo powerstroke that uses air to water intercooling and it's amazing how small the Intercooler is while still effectively limiting IAT at over 80psi of boost. The reduced piping is also a huge benefit when you are working with an engine bay that had no room to begin with. 

The problem is even with a massive heat exchanger the water becomes heat soaked, not to the point where it's dangerously high, but to the point where IAT's are higher than it would be with a traditional air/air Intercooler. 

Overall would I say the system works well? Yes. Is it cheaper/simpler/better? I think that is entirely dependent on application but I argue it's very unlikely that a budget air/water system will perform better than a budget air/air.


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## Mr. Brown Pants (Aug 8, 2016)

Mk4VRSex said:


> Water is great at absorbing heat, that's the efficient part. Now remove heat from the water, that's the inefficient part.
> 
> Proper coolant flow, proper sized heat exchanger.. this can all be achieved but you quickly learn air to water isn't simple and cheap as some think it is.
> 
> ...


Great information as always :thumbup:


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## dubbin'0n15s (Sep 27, 2005)

I run an air to water setup on my VRT. After some spirited driving, the intercooler is barely warm. Also, key is to get a good flowing pump for the water. I have the bosch cobra pump, it is relayed to my ignition.


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## Mr. Brown Pants (Aug 8, 2016)

dubbin'0n15s said:


> I run an air to water setup on my VRT. After some spirited driving, the intercooler is barely warm. Also, key is to get a good flowing pump for the water. I have the bosch cobra pump, it is relayed to my ignition.


Where did you get your setup from?
Any hick ups during install or while driving?


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## tmoura (Jun 27, 2006)

Here's my setup, intercooler and heat exchanger upfront are designed for a 1200hp setup. They are way larger then they need to be. With that and the highflown pump. I shouldn't have any heat soak at all. I'm also running feed and return lines down the center tunnel to the tank. Tank is being welded up and will sit in the rear quarter panel where the passenger speaker is. This will give me tank size of roughly 3+ gallons. Pump is controlled by my Plex Tuning EBC.




























Pump Setup









Heat Exchanger


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## Mk4VRSex (Jun 18, 2011)

^ beautiful setup, and I have no doubt that will work very well. 

To answer part of the OP's question, was it more affordable than an equivalent fmic?


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## tmoura (Jun 27, 2006)

Mk4VRSex said:


> ^ beautiful setup, and I have no doubt that will work very well.
> 
> To answer part of the OP's question, was it more affordable than an equivalent fmic?


Yes and no. Yes if you just went with the 1200 hp kit from Frozenboost. That runs less then $500 if I'm remembering correctly. Mine has a lot of customization so it's more.


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## Mr. Brown Pants (Aug 8, 2016)

tmoura said:


> Yes and no. Yes if you just went with the 1200 hp kit from Frozenboost. That runs less then $500 if I'm remembering correctly. Mine has a lot of customization so it's more.


Another amazing setup! 

Thanks for the info as well

After some more research I have come to the following conclusion: 

1. FMIC's are a tried and true way. Basically no matter what baring a boost leak at a connection they work plain and simple. Installation of the pipe might be a bit more tricky but that is really the only hick up during install. They seem like they are easier to trouble shoot as well if there was a problem. 

2. AWIC's are more complex, and introduce a few more failure points. To get maximum cooling another tank for ice should be installed. They seem as efficient or slightly better than a decent FMIC setup. They are more customize able and can be hidden to the outside eye (no FMIC at the front bumper to give away turbo). Can give slightly better throttle response due to short pipe run. 

Overall from a cost perspective both seem about on par with each other depending on how much customization is needed.


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## 8vlove12 (Jan 8, 2008)

I run an air to water setup on my 16v ABA setup that's daily driven. After hard driving and Texas heat , the intercooler has only been hot once. i prefer it over a FMIC just due to a much cleaner look and it keeps temps down much more vs a FMIC.


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## Mr. Brown Pants (Aug 8, 2016)

8vlove12 said:


> I run an air to water setup on my 16v ABA setup that's daily driven. After hard driving and Texas heat , the intercooler has only been hot once. i prefer it over a FMIC just due to a much cleaner look and it keeps temps down much more vs a FMIC.



Nice clean setup. My old MK3 used to look just like yours, on the outside that is. :thumbup:


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## vr-vagman (May 15, 2010)

...ops! wrong forum


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## Norwegian-VR6 (Feb 6, 2002)

Mk4VRSex said:


> ^ beautiful setup, and I have no doubt that will work very well.
> 
> To answer part of the OP's question, was it more affordable than an equivalent fmic?


Mk4VRSex Ive sent you a PM.


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## -:VW:- (Jan 27, 2006)

Sorry to bring this up from the dead but are any of you running the heat exchager (Frozen Boosts Type 100) in front of the radiator without a fan? Or is the fan needed in this particular application. I'd like to be able to screw it right into the front rebar via the top to mounting points and roll with that. I'm NOT planning on doing an ice box in the rear for what it is worth. The car is used on the street/highway and ocasional road and auto course duty.


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## Butcher (Jan 31, 2001)

Like many cooling system the fan only comes on when the temperatures start to get high. Since the intercooler is not critical [not as critical as a cooling system] then you can probably be ok without a fan. If you think about it, you are not going to produce a lot of power unless you are moving.


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## -:VW:- (Jan 27, 2006)

Ok thank you. Last q did you vr6 guys have to remove your PS and wiper fluid reservoirs to fit the core? Also for those with out the reservoir how are you filling and bleeding it?


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