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