Ask Sarah: What are water to air intercoolers?

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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