Air-to-water intercooler

[BigRabbitMan]

Due to space limitations and other factors, I am strongly considering replacing my air-to-air intercooler with an air-to-water intercooler.

Has anyone run one in highway use or know of someone who has? And if so, what was the experience with it.

[Kennedy]

The air to water IC's that I am familiar with are more of a race thing. They use ice water in a tank to circulate but these are short duration events.

[DmaxMaverick]

As John said, use that I'm aware of is pretty specific, and not really practical for regular/daily use.

The problem is, no matter how you do it (all else being equal), the same volume of heat still needs to be transfered to atmospheric air at some point. Engine coolant isn't a practical option, as it too, must be cooled by air, it's too hot, even on the "cool" side, and the I/C heat would then be transfered to the engine. Ultimately, you'll need a self-contained system: Pump, exchanger, condenser, and all the associated plumbing. In the end, it will be much more costly, with at least, a marginal loss of efficiency.

One practical use may be a situation the I/C condenser must be a significant distance from the intake plumbing. Smaller coolant lines are more simple to route, and much smaller than large intake plumbing.

[BigRabbitMan]

As has been stated above, virtually all of the references I have found have been for race use where a lot of heat has to be gotten rid of in a short period of time. This is using either/and/or an ice box or a small dedicated separarate radiator.

The interesting thing about these systems is that the questions come up about getting rid of the heat, not the efficiency of cooling the air. I can't find any references to issues relative to the cooling of the intake air. For that reason, I feel the intercooler side of the system must work efficiently.

In my application, I am space limited for an air-to-air system, but have room for the separate system to cool the cooling water. As a consequence, I have ordered a water to air system which includes the air to water unit, a small radiator with fan to cool the water, and a small electric pump to circulate the water. I will generate much less heat/min in road use than is generated in racing use. The Duramax will be pushing a load of 14,500-17,500 lbs. on a continuous basis.

The intercooler portion of the system is rated for 700 CFM while the Duramax will generate about 350 CFM at 3000 rpm and 2/3 of that at a cruising rpm of 2000. Under cruise conditions, I will be at much lower boost pressure and therefore lower heat loads than is experiences while racing.

The heat load will not go into either the engine coolant or the air cooling the engine coolant.

I am confident that the system will give me good intercooling on my road trips. I should be up and running sometime in June so we will then know for sure how well is does or does not work. The cost of the system is competitive with quality air to air intercoolers.

Thank you for your input. Hopefully, I will remember to come back and give a performace report once I am on the road.

[DmaxMaverick]

BTU's is BTU's. Plain and simple. They need to be moved, or they soak. The result, if not kept in check, is progressive meltdown.

The "350 CFM" is relative to the displacement at RPM, which is near accurate for a 6.6L N/A engine. At about 20 PSI IAC, that displacement becomes more than 4X that, effectively. Gasser system calculations don't work with Diesels, for that very reason. A typical gasoline/turbo engine will charge around 8 PSI, at best . The mathematics don't add up. You're gonna find more BTU's than you can deal with, without a doubt.

[BigRabbitMan]

I realize that CFM of the air and MASS of the air flow are two different things. I also realize that heat calories are a function of both CFM and air MASS or Density. The CFM of the PRESSURIZED air stays the same at a given RPM, but the MASS of the air and calories of heat in a single CF of the air increases in proportion to the increase in pressure.

Heat soak in the system is not a given, but will only occur if the cooling side of the water to air system is not capable of extracting the heat calories from the water at the same rate that the intercooler is putting heat calories into the water.

It has to be a balanced system, to that I agree. The critical number is heat calories that need to be removed and not CFM.

Under extreme situations the safety relief in my case is partially lifting the right foot since I will not be in a race or running against a clock.:)

[DmaxMaverick]

The CFM, be it an effective figure or actual, is absolutely essential. Mass means nothing, as an independent value. Compounding the CMF is relevant, in relation to the CFM at atmospheric pressure, in that, 1 CFM at 1 Bar, will contain X amount of heat (calories, as you state). Compounded/compressed, the actual CFM is irrelevant, as the compounded heat is the same. A pound of feathers or a pound of bricks. The only difference, effectively, between the two is the volume they occupy, at their "normal" density. Either can be modified to occupy the same volume as the other. This makes the values irrelevant, except the energy required to "modify" them, or in this discussion, the energy required to modify atmospheric pressure to a compounded value: compressed atmospheric gas to increase the density of O2 in that volume of atmospheric gas. Compressing a gas doesn't "create" heat. It doesn't get more hot. The BTU's remain the same, regardless of the state of density. The heat only "seems" to increase, but in fact, it's the same heat, the only difference being the volume it occupies.

As I said, the heat must, at some point, be removed to the atmospheric air. The addition of more physical points of transfer reduces its efficiency. Ideally, the heat must be transfered at the soonest convenience, which is the point. It's a matter of convenience, or requirement of the application. If your application requires a less efficient system due to physical limitations, it becomes necessary.

In your case, with your pusher configuration, you only need to consider the space available for the necessary components. The (CAC) radiator requirement is near the same, regardless of the method, and actually more favorable toward air-air, as there will be less efficiency loss, and (many) fewer points of failure. The only advantage to an air-water-air method is the ability to spread the volume of components over a larger area, although the overall system volume will be near the same as an air-air method. Big air pipes take up a lot of space with little option for placement. But then, heat exchangers aren't small, either.

[rapidoxidationman]

This thread is useless without pics.

I'm curious as to whether the OP is trying to reinvent the wheel or whether he's got some kind of unique truck with a DMax engine shoehorned in that somehow limits the space available for the air cooling system that the engineers designed for it. Doesn't seem like he's trying to do anything out of the ordinary with towing a heavy load on a regular basis.

OP, what's different that you feel like you need to rethink the intercooling system? If you post up specifics instead of generalities you might get some way better answers and insights.

Edit: How about a 50 gallon drum of water, a bit of hose, a small pump, and a spray nozzle to fan water on the intercooler for when things are getting hotter than you're comfy with? Distilled water would be best since it won't have minerals that'll condense on your coils.;)

[DmaxMaverick]

He's "shoehorning" it into an FMC pusher. There could be location and space issues. Lots of pics, just follow his signature link. Nice pics, and very well documented.

[DmaxMaverick]

......
Edit: How about a 50 gallon drum of water, a bit of hose, a small pump, and a spray nozzle to fan water on the intercooler for when things are getting hotter than you're comfy with? Distilled water would be best since it won't have minerals that'll condense on your coils.;)

Not a bad idea. Sounds like something I'd try. Since it's a motor-coach, a large water supply and pump are already on board. WMI may also be an option. I'd do it, just because.....

[BigRabbitMan]

As has been said above, the Duramax is being installed (not "shoehorned") into my FMC motor coach. It is a rear pusher and the Duramax is replacing a Chrysler 440.

Here is a picture if it works :)

http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=77&photoid=2871

This picture is on page 18 of the 19 pages of pictures with descriptions that follow this project from the start to where it is today.

As can be seen, there is lots of room except longitudinally. That is the space limitation that I stated exists in my original post. That is why I have decided to go to a different intercooling system than the traditional method. Yes, it has more components and posible points of failure, but it is such a simple system mechanically as compared to all of the engine/transmission components I don't feel that I am creating a significant failure point.

A barrel of distilled water has been suggested. It will take a pump to get the water out of the barrel and onto the intercooler. The water to air system also uses a pump to circulate the water between the intercooler and the dedicated radiator. Not a lot of difference in complexity, but a huge difference in weight and space requirements. The water tank that is already onboad is for domestic uses and should not be distilled water. A misting system requires distilled water.

I understand that in a front engined truck, there is no reason to do anything other than the simple air to air system. Up until recently, that is what I planned to use as well. I would be using the same system except for two reasons. The first is that I am running out of room longitudinally between the front of the engine and where the outer grillwork will be placed. The second is that it is a pusher arrangement with NO ram air and that it requires a pusher fan. Pusher fans are inherently less efficient at generating air flow through a radiator than puller fans. But I do not have a choice in this. I can have the pusher fan push air through one radiator (the main engine radiator) that has a very high heat load, or through two radiators. The engine radiator and the air to air radiator. Pushing air through two radiators will marginally reduce the air flow and will present the engine radiator with warmer air that it will without the air to air intercooler.

As a result of the combination of the two factors, I have made the decision to move the cooling of the intake air from its traditional location to a different location. I can't do that very effectively with with an air to air intercooler without ram air to work with.

I see no reason that it will not work provided that there is sufficient capacity to cool the water used in the water to air intercooler.

What I have wondered but have not asked, is what is the range of temperatures experienced for the intake air (post intercooler) for the stock Duramax in a normal truck? Until someone with a DMax truck can give me those numbers, I will not know if my intake air is running higher, lower or similar temps as a stock truck.

Thank you for your input,

[DmaxMaverick]

The charge air temps can exceed 150° Delta (departure from ambient temp). If you are considering placing your CAC condenser in the same stack as the engine cooling radiator, it will be worse than the OEM CAC's, in regards to efficiency. The same BTU's will still have to be moved to atmosphere, and if that's in the cooling stack, that's where it goes (some of it back into the engine cooling system). Still, if it will fit and you can plumb it, an air-air will be much more efficient. If you can't arrange a remote, self contained condenser, air-air is the only practical option if the plumbing will fit. Otherwise, you'll have to live with the efficiency loss, which can be significant at the most inconvenient times, like when you really need it (queue the foot control). Why not then, abandon the entire CAC idea and go with WMI, or reduce the power to a point it isn't needed, at all? Even then, it will be a significant step up from the original available power.

[a5150nut]

BigRabbitMan

Have you concidered a roof mount for your air cooling radiator?

If it was air to air you would get way to much turbo lag. But to cool your water, why not roof mount? Lay the radiator over at a 15, 20 degree angle with an electric fan on it. Build a housing around it to look like another roof mount AC unit? I am sure yo can find somewhere to run two water lines thru an interior or exterior wall. And you would gain your forced air effect too.

If one radiator doesnt work, how about two or three low profile radiators plumbed in series? You could probably mount an electric fan or fans in the top blowing up to help keep the low profile with the opening in the front for the forced air effect.

Good old fasion fiberglass would make a nice form fitting cover. Could design it to look like it came original.

Just an idea?

[More Power]

BigRabbitMan

Have you concidered a roof mount for your air cooling radiator?

If it was air to air you would get way to much turbo lag. But to cool your water, why not roof mount? Lay the radiator over at a 15, 20 degree angle with an electric fan on it. Build a housing around it to look like another roof mount AC unit? I am sure yo can find somewhere to run two water lines thru an interior or exterior wall. And you would gain your forced air effect too.

If one radiator doesnt work, how about two or three low profile radiators plumbed in series? You could probably mount an electric fan or fans in the top blowing up to help keep the low profile with the opening in the front for the forced air effect.

Good old fasion fiberglass would make a nice form fitting cover. Could design it to look like it came original.

Just an idea?

That's what I'd consider.

That said, I have communicated with some, who completed a Duramax/Allison conversion, and due to space limitations simply left the intercooler out. In my phone conversations with them I said that it could work for vehicles that aren't worked hard. After all, the first Chevy 6.5s, Dodge Cummins and Ford Powerstrokes didn't run with an intercooler. Of course, all this assumes the engine cooling system works very well. Jim

[BigRabbitMan]

A couple of points to respond to:

The first is location of the water to air intercooler. As originally stated, there is no room for a double stack in the traditonal location and to place the radiator for the water to air intercooler there would be self defeating as stated. Facing the rear of the coach, the water to air intercooler will be in the upper right portion of the engine bay. That will put it completely above the opening that you can see in the rear of the coach and slightly above the air outlet from the turbo.

The second is the location of the air to water radiator that cools the intercooler water. That will be at the far left where it will have cool, ambient air and will not discharge heat into the engine cooling complex. It will have its own electric fan to ensure continous cooling action. Yes, the system will have two electrically operated components: the small water pump and the fan for the radiator. The fan will be temperatue controlled. The pump will be always on.

The cooled intake air will pass from the upper right corner across to the left (behind the lower portion of the body molding and above the engine radiator) and then down and into the engine intake.

A roof mount for the engine radiator was considered; however, one of the things that I like about the coach is its clean body lines. There are NO roof AC units as it has basement AC. I don't like "warts" on the top of the coach and that would add a lot of complexity to the project.

The concept of putting two short, wide radiators up under the front of the coach to take advantage of ram air to cool the engine has been discussed. I may someday do that but that also adds significant complexity. It would have to be a separate project. If it worked, I could then go back to an air to air intercooler (remember: room for one radiator only).

Here is a link to a two page, many post discussion in 2006 on the FMC Club website about my concept of moving the engine radiator from the rear to the front of the coach. Please note the risistance to making ANY change to the system.
http://www.fmcowners.com/mbbs22/forums/thread-view.asp?tid=51&posts=43&start=1

A WMI (water mist injection) system has been suggested in place of the water to air intercooler. Yes, WMI reduces the temp of the intake air. But, I don't feel that one should abandon having ANY intercooler at all! That is just shifting the cooling challenge to another system that uses a consumable and is more complicated than a simple water to air intercooler. How large of a tank would it take to solely rely on such a system? Remember, distilled water is required.

In fact, I have purchased a WMI system that will be held in reserve and installed if, in fact, additional IA cooling is needed. It will only be in addition to the water to air intercooler, if needed, and not in place of it.

Just for background, you may want to also read this thread here on The Diesel Page that starts in 2007 and follows my thoughts and the path that has taken me to this point. Due note that the links in many of the earlier posts are broken. Here is the link: http://www.thedieselpageforums.com/tdpforum/showthread.php?t=27875

Again, thank you for your input and I hope this ongoing discussion helps educate others.

[BigRabbitMan]

That's what I'd consider.

That said, I have communicated with some, who completed a Duramax/Allison conversion, and due to space limitations simply left the intercooler out. In my phone conversations with them I said that it could work for vehicles that aren't worked hard. After all, the first Chevy 6.5s, Dodge Cummins and Ford Powerstrokes didn't run with an intercooler. Of course, all this assumes the engine cooling system works very well. Jim

Given that I will be at 14,500-17,500 GCVW, it is not light duty. To leave the intercooler out rather than install a different type of intercooler is out of the question. That is going backward rather than forward. The need for an intercooler is strongly documented when wanting to get performance from a Duramax.

I will have an intercooler, just a different type than what was stock. Time will tell how well it functions.:)