Air to water vs. Air to air IC?


Pelennor Fields
Feb 8, 2004
What kind of HP increase can one look to see with an Air/water IC vs. Air to air IC?
Brett on a race car they can be worth over 100HP depending on conditions.
"this would be on a race type set up"
Think about how much faster you will be with 70* IAT instead of 120+ on a warm day.
Now also consider you may be about to run a couple more psi and degrees timing as well.
A liquid intercooler will allow you to run near or possibly below ambient IAT's. However this is if you keep the fluid reserviour chilled aswell. At the track its easy to ice down the reserviour so it stays really cold but on a daily basis the fluid won't chill to ambient anymore and your stuck circulating 85ºF fluid on a 75ºF day which will give you higher than air to air IATs. Most road cars and endurance racers run air to air intercoolers because they are more efficient over longer streches of time and use. A liquid intercooler is a competition device or a space saving add on where you can't fit an air to air. I had a thread going about an freon powered liquid intercooler than used the cars AC system to chill the liquid on a burst basis that might be more along the lines of a daily useable intercooler that would get you well below ambient IATs. However it would be difficult to use at the track and you'd probably have to put a catch can in for the evaporator core drain so it would be track legal.
I need that 100 hp. I am building something liquid IC related. It involves electricity though. I will keep you updated.:eek:
IC, reservoir size and turbo efficiency have a lot to do with final air temps on such a system.

I have a data log in my old laptop of a 7 second drag radial Mustang 1/4 mi. pass with a liquid IC. The temps are solidly below ambient.
I have a friend who is building a blow thru Ford set up with the little brother to that IC on EBAY. Its the 1000 hp one. He believes it willl work in some degree. Untill he gets it running , theres no way to know. On another note for the money its hard not to take a chance on it.
I guess I can chime in on this....

For a little over 7 years now, I have been specing and selling air to liquid intercoolers. And here are some things that I have learned over that time.

Air to liquid intercoolers

First off, the best air to liquid cores out on the market today are and have been the Garrett high efficiency cores. The ones pictured above in the ebay link are the cheap knock offs that are coming in from China. They do not perform the same as the true Garrett cores do. Eventhough they are cheap as dirt, they do not perform the same as the Garrett core based air to liquid intercoolers do.

Over the years, PTE has tested them all and the Garrett cores are still the best. Water flow through the Garrett cores is very critical. You have to be able to move a lot of water through them to properly cool the cores down on high hp applications. This would be 1400hp or more. I do not recommend air to liquid intercoolers on a 90% street driven car, because of the fact of super heating the water while just cruising/not under boost. There are things that can be done to help lower the water temps down, but unless you have the reservoir packed with ice all-the-time, you will only be as efficient as the auxiliary cooler that cools the water coming out of the intercooler. And 9 out of 10 times, this can only be as efficient as an air to air intercooler. The only time I recommend air to liquid intercoolers, is when used on an all out drag racing application that will have the ability to drain, fill and circulate the reservoir and intercooler repeatedly between runs.

Here are the procedures and steps that a lot of my friends and serious racers have used in order to realize the full potential of an air to liquid intercooler. Everything from a 900hp Sport Compact application, to a 3500+ hp Twin Turbo Pro series race car.

You don't simply drain the water and pack it full of ice and run again. Nay Nay. If you don't have very much time between rounds (especially in the Pro series racing classes) you have to have your procedure down to minutes. Drain water just leaving enough in the bottom of the reservoir for circulation purposes, pack the reservoir full with ice, run the pump so that the hot water in the IC core and lines will circulate through the reservoir. Keep circulating the water until the ice is completely melted in the reservoir. The core should be cool (not frosty) to the touch after about 4-5 minutes. Now, drain the water out again, leaving just enough in the bottom for circulation when you pack it with ice a 2nd time. Now, 5 minutes before you make a pass, it is recommended to circulate the water to the point of frosting up the pipes and the IC itself. Drain the water and repack one last time just before being called to the lanes.
Some people turn on the pumps before the burnout, and some do it after. To me, it would make more sense to turn it on after the burn out so you're not melting your ice prematurely.

But as you can see, air to liquid intercoolers require maintenance between rounds at the track. If you are not willing to adopt these procedures, then it's not for you. But the real benefits of an air to liquid intercooler vs an air to air in a nut shell are this,

- Very cold charge air temps, when the system is properly setup with the correctly sized water pump/pumps, reservoir size and line size. In some cases we've heard reports of 50* charge temps crossing the traps on hot 95+ degree days on 2000-3000hp applications.
- Naturally, more hp due to cooler charge temps, as well as being easier to tune your combo because of the stable charge temps that are not affected by ambient air temps. The air to air intercooler is a lot more susceptible to changing ambient air temps, which can dramatically affect your tune up.

The bottom line is this, the air to liquid will make more power than an air to air, but it requires maintenance and is not street friendly.
The air to air will make power and is pretty much a put it on and forget about it deal, but due to size constraints can cause a problem on serious hp applications. This point is typically reached at around the 1400 flywheel hp level.

Hope this helps.

Patrick, for $250 i am willing to try the cheaper core, I can;t see spending $1200 on a core right now. I will let you know how it works. Thats a great response, gives me some stuff to think about in this project.
Hey Pat can you repeat that.....? :tongue: J/k. That was some very good info. Explained it better then its ever been explained to me before. I Appreciate it.
One more thing? So the air to water would actually be worse then an air to air when driving on the street after the water heated up? Or would it be as efficient as an air to air but no more efficient until the water was cooled again? Thanx....
It could actually become worse. Once the core gets hot enough to actually evaporate the water, you would simply have a super hot chunk of aluminum that has no way of cooling the charge temps. Even with a little bit of ambient air flowing onto one side of the core, it still would be horrible without cold or chilled water flowing through the core. A long time ago, I ran the Eastern cold box for a stock intercooler. I learned that even driving the car for 10-15 miles, the water would get so hot that it would completely evaporate all the water and the IC would get very hot. I even tried it with the cold box packed full of ice and the entire IC completely covered with insulation foam. No dice. It wasn't long after that, that I removed it and reverted back to an air to air. That was back in '94.