Teach me about air/water intercoolers

I've just sealed the deal on a 99 E350 Powerstroke van. One of the shortcomings of the vans is that Ford never found the real estate to include an intercooler. Some owners have custom fabbed air/air intercoolers to fit where the grille used to be, but that is not only expensive but its highly susceptible to damage.

So I was thinking about tucking an air/water intercooler somewhere but I know next to nothing about them. Do they use a dedicated water supply with its own pump? How big does the heat exchanger for the water need to be? How much heat does the exchanger put off? If I put the cooler in front of the condenser, will it create enough heat that it might affect things like engine temp, or the oil cooler/tranny cooler? Does it need its own fan?

I've read about setups with electric water pumps that kick on at a certain manifold PSI, but that sounds complicated.

Basically... WTF do I do? Will it be worth the complexity?

They are generally more efficient than air to air designs. I fabbed up one on my turbo CRX many years ago. Too much to write here at this time (at work). PM me if you want more info.

Their efficiency is not automatically better for several reasons. 1. The air to be cooled heats the water. 2. The water is moved by an electric pump to another radiator. 3. That water is then cooled by the air.

At each thermal interface there is a loss of efficiency. Without detailed airflow data, the air-to-water system has no guarantee of being better. They're also heavier, can leak, need an electric pump, and may or may not package better. Can they work better, yes, but there's no guarantee of that.

Because of limited time on boost air/water intercoolers have plenty of time to cool the water (just have a big enough water reservoir to increase efficiencies) and therefore there isn't the inevitable loss of efficiency that kb58 says.

But as he says you must have a good way to cool the system.

Interesting question. My only knowledgle of them is an aftermarket supercharger kit for Volvo B20's uses a air/water/air heat exchanger set up. Apparently works well enough, although we're dealing with an engine 1/3 the size.

Personally, I'd probably look more at figuring out ways to cheapen the cost of the grill replacement air-air set-up, then add a brush/grill guard on the bumper with some screening to act as the grill.

Air to liquid chargecoolers are good when you don't have the space to go air to air.

Esprit SE's (910 motor) use a Garrett charge cooler, air to water. Earlier models had a completely separate water system. Later models shared the coolant tank with the engine coolant, but still had a separate water pump and radiator. A common mod is to replace the mechanical water pump (prone to failure with the vanes breaking for various reasons) with a small electric pump. Esprit SE fronts are: Chargecooler radiator, AC radiator (condensor), engine radiator, if I recall, plus the oil coolers on both sides.

I have a ebay search somewhere that I occasionally use to look for a Garrett charge cooler. The ford truck thing, Lightning or whatever, came with a charge cooler that looks almost identical to the one used on the Esprits. Not all of the Lightnings had the same one. I think the early one had the separate one and the later ones had it built into the manifold or something.

I've always understood that air-to-air intercoolers were always more efficient than air-to-water.

It's not just that you have more thermal transitions, it's also the temperature of the cooling medium. In an air-to-air, you're getting outside air, which at it's hottest is ~120 degrees. In an air-to-water, you're using engine coolant, when at temp is going to be at a minimum of 165 degrees, and more likely 180+

been looking into AWIC... I like the concept and compactness to efficiency ratio... for some serious cooling you can use ice and get better then 100% efficiency cooling

I knew an mr2 guy who did the most simple awic you could possibly pull off... he cut holes int he firewall (engine is sitting behind you) and mounted a cooler behind the passenger seat... the air/air IC sat in the cooler and then was filled with ice... no motors or anything else... when ice melted remove the water and dump in another bag of ice.

but anyway... this guy has some good info on a basic setup with numbers on a DIY AWIC (and water injection which may be another option for you)...

http://www.key-ideas.com/MerkurPage.htm

The new 2011+ 6.7's have air to water intercoolers. Find a wrecked one, or you can always order the parts. You'll need the intercooler (duh), a fluid pump, heat exchanger for the fluid, and all the lines and stuff. You may be able to rob all the lines & pump and all that stuff from the 2003-2004 Cobra or a Lightning.

dexter... a proper AWIC system doesn't use engien coolant... it uses it's own system... check out the link I posted before...

basically it's an intercooler with a water jacket on it... a pump moves water to a heat exchanger (commonly a motorcycle radiator or a few oil coolers) which cools the water and then goes back up to the IC to absorb heat again...

Do they have a rear mounted a/c system available on the E-series vans? (like on older suburbans?) If so, you could use the direct expansion refrigerant circuit instead of the water to remove the heat.

Or use a hybrid water and DX system.

ReverendDexter wrote: I've always understood that air-to-air intercoolers were always more efficient than air-to-water. It's not just that you have more thermal transitions, it's also the temperature of the cooling medium. In an air-to-air, you're getting outside air, which at it's hottest is ~120 degrees. In an air-to-water, you're using engine coolant, when at temp is going to be at a minimum of 165 degrees, and more likely 180+

True, but water has hundreds of times more heat capacity than air. Stick your hand in a 200 degree oven and it feels warm. Stick your hand in 200 degree water and you'll be needing skin grafts.

RossD wrote: Do they have a rear mounted a/c system available on the E-series vans? (like on older suburbans?) If so, you could use the direct expansion refrigerant circuit instead of the water to remove the heat. Or use a hybrid water and DX system.

There is an optional rear A/C and this van is not equipped with that option. I am however concerned about the whole first law of physics thing... I think if I installed the necessary parts for rear A/C, I would be using more HP than I could possibly gain. Moving air is "free," or at least a constant. Generating a heat differential with an A/C compressor to cool the intake charge isn't.

http://www.frozenboost.com/

FYI: 05-06 chevy Cobalt SS use air to water cooler under the supper charger.

But no matter what, once you reach thermal equilibrium, eventually you have to conduct the same amount of heat to a moving airstream. Given that the max temperature in the charge (and thus the max temp in the exhange medium, water or air) will be the same, it requires the same amount of cooler fin square footage exposed to that airstream. It's true that a liquid cooler will require smaller internal passages, but how much smaller can the cooler be given above? One advantage of liquid though, is that it's easier to mount it in remote locations (like inside the rear fender/wheelwells, where many trucks have a lot of wasted space).

curtis73 wrote:

RossD wrote: ... you could use the direct expansion refrigerant circuit instead of the water to remove the heat...

...I am however concerned about the whole first law of physics thing... I think if I installed the necessary parts for rear A/C, I would be *using* more HP than I could possibly gain...

I'm not sure if the logistic of using a refrigeration cycle to cool the intake air will work without running all of the numbers, but you wouldn't have to worry about breaking the 1st law of thermodynamics to make it work.

The refrigeration cycle in real equipment can move 3.5 times as much heat as it takes to drive the system (COP around 3.5)

Water pumps and pumping water have inefficiencies too.

That's true. My main purpose for adding an intercooler is because I do a fair amount of heavy towing and EGTs. I also would love to add some extra fuel for non-towing times with a switchable tuner.

I understand that using an A/C compressor to cool the heat exchanger will be pretty effective, but it might draw 15 hp to simply displace the heat elsewhere. I'm just thinking that airflow from forward motion (while not as effective) is already a constant.

I'm off to read up on that frozenboost site.

My physics teacher is rolling in his grave... When it's touted as better, better at what? Packaging? Maybe. Thermally? Only if the overall efficiency is better that air-to-air, and having two thermal interfaces puts it at an immediate disadvantage. Can it be overcome? Maybe. Is it inherently better? Define better.

There was a company that had a kit that would put an extra evaporator core into the media reservoir for the intercooler. You would let it basically freeze that media for a minute or so and then hit a switch to introduce that into the intercooler for a quick burst of super coldness. Worked great for street racing or at the drag strip.

What would happen if a person used the core of the A/W I/C as an evaporator for a compressor?

I would think that consistent 300-degree input air would quickly overload the condenser causing the compressor to shut off, effectively bypassing the intercooling properties.

What kind of temperature drop can you expect from the intercooler in this application?

Found a water/air intercooler install link for ya.

ReverendDexter wrote: I've always understood that air-to-air intercoolers were always more efficient than air-to-water. It's not just that you have more thermal transitions, it's also the temperature of the cooling medium. In an air-to-air, you're getting outside air, which at it's hottest is ~120 degrees. In an air-to-water, you're using engine coolant, when at temp is going to be at a minimum of 165 degrees, and more likely 180+

No, you are not using engine coolant. Air-water intercoolers use separate coolant.

the problem I see with the AWIC in your case is your intended usage.

Big Diesel doing big towing. That means a LOT of time underboost.

You are going to have to carefully figure out your thermal reserve and your cooling.

The good news is.. the radiator to cool the intercooler can be small. If you get one custom made, you can make it tall and wide and not deep.. this means you can fit it infront of the radiator and condensor in front of the van where airflow is best.

As for the pump.. I would look into a mechanical waterpump.. I think Chrysler and the later saab 9-3s had a pump you could reuse for your purpose. The electric pump would work great.. but as you would be boosting a LOT.. mechanical would be better.