Hi, first off I have to say I'm a huge MotoIQ fan since I was shown your awesome website by a friend. I have read as much as possible, soaking up all the information I can.  I'm in the middle of a total rebuild of an old Nissan and the information found on your site has helped my project in the right direction.

But to the actual question: Lately I have been searching for information about "water to air intercoolers."  I have seen these in some of your articles but not much information is mentioned. From reading on forums, there are people swearing there is nothing better and of course, those who have the opposite opinion.  Naturally this system would be compared with a normal air to air intercooler.  Do you have any good information regarding this subject??

Best regards,

Kjell Ovrebo 

Time Attack NSX water air intercooler
Up close and personal with Billy Johnson's Time Attack NSX, we can see the heat exchanger for the water to air intercooler.  After the water passes through the intercooler and absorbs heat from the boosted air, it goes here so it can be cooled down.
Glad you're enjoying MotoIQ, Kjell - pay it forward and tell all your friends!  There are two types of intercoolers: air to air and water (liquid) to air.  Water to air intercoolers use a separate but similar cooling system like the radiator for the engine.  Water to air intercoolers pump water (or other cooling medium such as a water/glycol mixture) through the fins to cool the intake charge.  This system requires two heat exchangers, one to transfer the heat from the intake charge to the water (or coolant) stream and the other to release the heat into the atmosphere. They also require a pump to circulate the water and reservoir for storing the water. 
 Toyota Tundra water air intercooler
How's this for compact packaging?  Our Project Toyota Tundra uses this beautiful TRD blower with integrated water to air intercooler.  I don't think it gets much cleaner than this!
At constant pressure, air has a specific heat value of 1.01, but water has a heat value of 4.18. This means for each increase in air temperature by one degree, water can absorb 4 times as much heat, making water to air intercoolers more efficient at absorbing heat from the boosted air.  A typical factory turbocharged engine uses an air to air intercooler that's about 50-70% efficient.  A large aftermarket intercooler can get to about 85% efficient and a properly set up water to air intercooler can have efficiencies around 90% or higher. They have shorter, less laggy plumbing and can be packaged more easily (and sometimes more stealthily) in cramped engine compartments, letting the engine radiator take the prime real estate space in the front bumper- useful for engines that tend to run hot.  An ice tank or circulating ice water could even lower the intake temps to below ambient, which will provide a considerable advantage for a quick burst of power.

Got a difficult tech question? Email Sarah at asksarah@motoiq.com

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Wednesday, August 24, 2011 7:40 AM
Wow, learned something again about the difference in the tube and fin vs the bar and plate.
Nice article as always.
Wednesday, August 24, 2011 3:49 PM
Yes, great article. Love the clear, simple explanation of the pros and cons of the 3 major types of intercoolers. It becomes very clear that there really is "no free lunch" with intercooler choice/design and the choice boils down to what's best per application not some cure-all intercooler.
Friday, August 26, 2011 3:23 AM
I've experimented with both water/air and air/air coolers

With (aftermarket) water/air setups, typically used in drag racing applications, you have to consider that the intercooler will 'sweat'; condensation forms around the ice cold cooler, and therefore a dripping fluid can be a tech inspection issue. Hence why you will find most of air/water setups mounted in-cabin on these drag cars, as mounting it outboard can be a hazard. This means you're stuck routing charge piping through the firewall.

On the other hand, with the brilliant efficiency of the water/air setup, you can push the compressor way off its normal efficiency range, and squeeze out the very last bit of power from the turbo/fuel system.

I had a huge turbonetics/spearco catalogue core I used for a period of time (back when I was more drag crazed), but I ditched it in favor of air to air, and haven't really looked back. The added weight, maintenance headaches, complexity, heatsoak, street-car-unfriendly-ness, just some of the reasons.

One of the biggest issues I had when looking to get into an air/air cooler to replace it, was choosing which brand to trust.

There's too many $100 ebay coolers out there. There's too many 'name-brand' coolers using the same $100 chinese cores in their builds. There's too many knock-off $100 chinese coolers, indistinguishable from their authentic counterparts. There is VERY little valid, factual testing or information available out there to help you choose what is a quality setup. I've cut no corners on my build, so I didn't want to buy a $100 ebay cooler, or a $700 name-brand cooler with the same quality/efficiency of a cheaper unit.

Building another custom cooler from a high quality piece sourced from the turbonetics/spearco catalogue again would cost a fortune, so after a good deal of research, I found the Nisei race intercooler for the EVO platform, a PROVEN unit, at least proven enough that I was confident enough to lay down the $1000 for it. Been running it on the miata ever since.

MotoIQ needs to do a followup article on the intercooler aftermarket, disseminating information, present REAL data, and maybe do a bit of a shootout...
Friday, August 26, 2011 4:07 AM
Is there any benefit to some of the vertical air flow intercoolers you see around... I know APS used to make one and now I think AMS has one for the R35... does it reduce pressure drop or simply just increase the area over which the heat exchange takes place

Also is the v mount intercooler and radiator set up the best approach to road racing to give both of the components as much air as possible
Der Bruce
Der Brucelink
Friday, August 26, 2011 12:26 PM
Good stuff Sarah! I hadn't realized the TRD supercharger had the built in water-air intercooler.
Monday, August 29, 2011 9:58 AM
I read an article years ago regarding intercoolers and the gist of the article is that they don't work the way you think they work, namely, they act more like a heat sink rather than heat exchanger (like a radiator).

Think of it this way, your driving along and are about to merge into traffic. At this point, your turbo engine isn't making boost and everything is heated to roughly ambient temperature or a little above.

When you floor the pedal and begin to make boost, the heated air coming out of the turbo transfers it heat to the intercooler, cooling the air but heating the intercooler beyond ambient temperatures.

Once you've merged and stop boosting the engine, the intercooler begins transferring the heat it absorbed back into air going into the engine (now roughly ambient since it's no longer being heated by the turbo via compression) and this is the primary temperature difference that cools the intercooler back down. This sounds counterproductive (heating the incoming air to the engine), but if turbo engine isn't making boost, hotter air isn't really affecting it since it's not being stressed.

The surface area and the whole "air to air" part of the intercooler were really just to help maintain the cooler at ambient temperature and avoid heat soak. It doesn't really have much of an effect on cooling the incoming air charge from the turbo.
Tuesday, August 30, 2011 1:38 PM
Long time reader, just joined.

Sarah not sure if you read all of these messages. I tried to message you, but only your friends can do that. I really like these articles and I find myself re-reading them often. They are great.

Could I propose an article about waterless engine cooling. I'm just hearing about this and I'm not really sure it is for me, but I'm doing a rebuild and someone mentioned it.

Here is a company that have some products in the market.
Sarah Forst
Sarah Forstlink
Thursday, September 01, 2011 4:22 PM
cloud: Yes, sorry. I usually get email updates but I let my inbox get too full and it started bouncing like a car on cut stock springs. I don't have much personal experience with the evans cooling stuff or others. I did have a friend use it but I'm not sure if he found any benefit. Perhaps one of us can test it on a car.

Henry: Vertical I/C's have less pressure drop because of the shorter path but horizontal acts more like a heat sink (more cooling time). Bottom line- either config is fine as long as it's efficient and fits. I have a horizontal Spearco I/C (as you can see from the pic at the top) and never had issues with heat soak even at 26 psi.
Saturday, September 03, 2011 4:11 AM
Thanks for the clarification Sarah
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