I would run antifreeze for the anti-corrosive properties.

 

Ignore negative speculation regarding A2W intercooling from those who have no experience outside of the internet with it. If someone says it's only good for the track, they don't know the difference between a track only application and a street application, that being a heat exchanger.

My eng specs:
GM 3900 60 degree V6 stroked to 4.2L
11:1 compression and was 11.5:1 before the rebuild.
LS1 forged pistons (shares the same bore & ~ compression height).
Narrowed chevy H-beam rods.
Offset ground stock forged crankshaft, 3.31 to 3.555".
T-67 turbo, .81 turbine.
13 psi high point so far on 93 octane, A2W intercooled.

Before the A2W intercooler, inlet air temps reached 170 deg in the GA heat on as little as 6 psi. Cruise air temps were ~135 deg.

After my A2W install with 1 gallon of distilled water (I could use more) in the system, cruise air temps hoover about 10 deg above ambient and a 5 second boost pull adds less than 10 deg to the air temps not to mention a very low pressure drop through the intercooler.

If an A2A does that well in your application then that's what you should use.
Otherwise an A2W works wonders when installed properly.

You should use distilled water with an anti-freeze treatment to prevent freezing. Water is better than straight radiator fluid due to heat capacity. All hard parts are brass or aluminum so corrosion should not be a problem.

You should also have a reservoir capacity of at least 2 gallons and preferably enough water so that the water never circulates to the intercooler twice while in boost.

"Glorified tranny cooler" don't even think about it, the worst mistake you can make is using a non specific heat exchanger for an A2W system, especially an undersized unit for your power level.

As for the added weight, for every 10 deg drop in inlet temps you gain about 1% efficiency, so in my case I should have gained at least 8% efficiency. 1.08 times my engine's previous performance, not too mention the detonation resistance and ability to add more boost, more than offsets the added weight with a gain of more hp and tq than is necessary to accelerate it.

Take advantage of the modern technological advances present in todays engines and assessories, don't limit it with old rules. There are at least 3 boosted GM cars in production today that use A2W intercooling: Cobalt SS, Corvette LS7 and the Cadillac CTS-V. That should stand for something regarding A2W effectiveness.

The inlet air temps posted below are peak numbers so the averages in those cells are lower. Ambient temps were ~55 deg.

 

finally some common sense. im so sick of seeing people post on the net about a2w being bad on the street. it literally shows they have NEVER done it and only read about it. my car has a 5 gal water cell in the trunk. will never see ice either.

 

No, it doesn't. That makes no sense.

 

I agree with maticulus 100%. There are even people using a2w coolers on the street successfully without heat exchangers. With a large enough water reservoir, water won't be pumped through the cooler twice on a pull. In between pulls, the water will cool off. As long as you're not in boost constantly, you'll be fine.

 

Biggest deal with the A2W vs A2A debate is both systems being properly designed. Most drag only A2W systems would suck big wind on a street car, never meant to deal with the heat soak a street car produces. Most guys only have thought about these setups so the A2A is king in their minds...

Id take a proper A2W system all day long over an A2A, but A2A is simple as pie. If you have the room go A2A but there is a reason most OEM's go A2W. FYI, my subaru is A2W and my Lightning istoo, i have always seen lower ambient temps on my subaru even compared to the STi top mounts and guys with front mount A2A's. Guess what is going on my TA?
Of course, you can really go all out and go with a killer chiller and blow both setups of the water lol.

 

I joined this forum for that reason after seeing this thread to share my experience with A2W. Negative speculation and no experience posts are what lead to my investing about what I paid for the A2W system in an A2A setup attempt first. It worked, but the amount of plumbing was rediculous not to mention the pressure drop from all the twists and turns and the pipe diameter.

I should have been running A2W 10 yrs ago, unfortunately no one ever posted actual results of its effectiveness to counter the desent. The best thing about my setup is that I have a little tweaking to do to make it even better.

I didn't listen to the complaints about my compression ratio plans either. The advancements in combustion science have come a long way and although I run 93 octane, my 11:1 compression boost has hit double digits on midgrade fuel without spark retard. The stock version of my motor is rated for 87 octane with its 9.8:1 compression from GM.

Trend setting is nice.

 

Water is 14 times better than air at removing heat from aluminum. This why air to water intercooler cores can be so much smaller and still be rated the same.

They dont need heat exchangers either depending on how much water capacity you build into the system. Les than 2 gallons they can be a good idea.... especially on supercharged applications.

On turbo cars I have never ran an exchanger. The intercooler core itself will act as an exchanger if you run the pump when you are out of boost. VERY few people will have a turbo car that can heat soak 5-7 gallons of water in short order... thats alot of BTU capability to heat soak.

5 gallons is my magic number on tank capacity. Ive never had that much water heat soak to the point the intercooler was no longer effective.

No matter what the application... I'll never use an air to air. It will always be an air to water setup.

 

Which A2W company are people going with?

 

I dealt with siliconeintakes, they have great prices and great service. I had a problem with two orders in a row and they got right on it right away, even over nighting the correct heat exchanger when the incorrect one was sent.
http://www.siliconeintakes.com/index...8c9acab6c5f082

As for running without a heat exchanger, I don't have that much confidence in it. Water weighs about 8 lbs per gallon so I'll still have a pretty good balance once I upgrade my tank to a 2 gal capacity since 1 gal is doing so well.

Contrary to what some may think, the little rule pump that came with my kit works very well also. In my build thread a forum member called my build a science project and really insulted the idea of using the pump supplied with the kit. Once I posted my numbers he had nothing else to say.

 

Thanks for the reply and info. Ill look them up.

 

Silicone intakes/frozen boost/cx are all decent coolers. If you want the best, get one with a Garrett core. With an a2w, heat exchanger or not, I'd run at least a 5 gallon reservoir in the trunk. Sure, you can use smaller but there's not much reason to.

 

Yeah I gave up at that point no use in arguing with someone who has "read" all they need to make a decision on what will work best.

I am running a 5 gallon tank in the trunk with the big rule pump don't think I will have an issue with that much water in reserve.

 

This is an excellent thread for the intercooler ignorant -> Me. Thanks to all I now have a far better understanding of A2W.

 

So out of curiosity to the heat soak portion of this. I'm planning on going turbo, and I wanna do a2w. If I drive from Florida back home to Tennessee (8 hour drive) do I have to worry about heat soak if I run a 2 gallon tank? What about 5?

I wouldn't be racing every car on the wau there, just constant cruising at 70-80mph.

 

If you don't run a heat exchanger and you run your water pump for the intercooler it will get heat soaked. In reality most cars will get better or at least the same fuel mileage with hotter inlet temps. My best fuel mpg comes when I am over 125 iat when cruising, I believe it helps the fuel vaporize better at low engine speeds. I set up my primary intercooler water pump to only run when I'm in boost on the intercooler. I have a second pump that circulates my tank water into the heat exchanger when the tank is over 120F. When I ice the tank the temp switch won't run because of the low water temp.

Kurt

 

Kurt, I have heard that most of a A2W heat rejection is normally back into the intake air when the throttle is closed. Do you believe this to be the case?

If so how come you turn the pump off when you go out of boost? Would it not be better to leave it on for a short time after the run to help reduce water temps again? or maybe just turning the system off at part throttle rather than closed?

The trouble i have in my head is how do you get a HE big enough to remove all the heat? An A2A guy would normally use say a 24" x 12" x 4" core and they only have to transfer the heat form the air, through the alloy, to the air. On a A2W you have twice the transfers, ie air through the alloy to the water and then from the water through the alloy to the air.

 

If you continuous run the pump on the car I reference (Nova I no longer own) the water will level off between 130-140F. This car used A2W that are remote mounted with centrifical SC's. This engine produced 1160hp at the flywheel and had two small A2W cores hidden in the fenders. Roots type superchargers will be worse at heat gain because the intercooler is directly mounted on engine, but I have not tested that yet.

The main thing the water gives you is more mass to carry heat away, and using a reasonable duty cycle the water gets time to cool even with small HE. I ran 20 gallons per minute on my coolers with 10 gallon tank that normally had 5-7 gallons in the tank. That gives me 15 seconds of flow before I start sending the water twice. At 20 gpm with full power the temp gain leaving the intercooler is less than 20F. So if my water is 80F it will come out at 100F, and in 15 seconds of full throttle I should have brought the tank up to 100F. Now if it takes a small heat exchanger 3-4 minutes to get that water back to 80F (Mine did), is that acceptable duty cycle for a street brawler? This car went 0-150mph at the track in 9 seconds, so how many times in a row can you do that blast? If it was a road race type car the HE would need to be bigger because the duty cycle goes up, shorter bursts but more of them. A2A would be great if it could be sized right, but at 1160hp I would need a cooler bigger than the front of my car!


Kurt

 

Kurt, is there any rough calculation you can do to cal how much HE core you need to keep a setup cool? i guess its dependent on the efficiency of the chargecooler (low efficiency CC means less heat for the HE to remove) as well as the efficiency of the HE core.

Its just the GT500 guys seem to be able to road cause their cars with a Dual fan HE upgrade. They are pretty large units but noting astronomical. I guess they could live with higher IAT2s and just tune for them.

Also, have you come across any novel ways of getting move HE core in limited space? I saw the AMS TT Audi R3 V10 mounts its HEs down low at the rear of the car rather than running them to the front.

 

No calculations that I know of, so many different quality parts that look the same. HE and intercoolers I have tested with a simple test that helps me qualify them in my head.
I have a jet wash tank that runs the water at 200f.
I fill a 5 gallon fuel cell with water, this cell has a single Bosch water pump from the Ford lightning.
I pump the water into the part I want to compare and check water flow.
Equalize water flow with simple ball valve on both (or more) parts.
I use a small cage fan that is 120 volt that blows directly on the part.
I then fill the water tank with 5 gallons of hot water, the tank has a single thermocouple that I read with a meter for temp, normally I can get around 200F in the tank at the start.
I then start the pump and fan.
Then time the temp drop from 180F to 100F.
The better HE or intercooler will drop the temp faster.


Kurt