Has anyone tried to put both on their cars???? A2A going into a A2W in the fender????

 

Would you get enough air flow inside the fender, to exchange enough heat into the air to be worth your effort? Or would heat just collect inside the fender and become counterproductive? Even with a vented fender, I do not think you would get enough air flow.

 

Just to throw some gas on the fire. . .

Heat up 2 hunks of metal to red hot. Drop one in water, and let the other sit out in air. Which one would you pick up after, say 30 seconds?

If you chose poorly (air) and burn the piss outta' your fingers, are you going to waive your hand around in the air, or dunk it in water?

The 2 cooling media are orders of magnitude apart in cooling ability. Because of that, you can size air/water intercoolers much smaller, resulting in more room for turbo's, less pressure drop in the system, cooler air temps, or all three. This all assumes an adequatly sized radiator and ample system "capacitance".

Air/air only has an advantage in lack of complexity.

Mike

 

This has been debated for years and I wanted to stay out of it but there is a lot of misleading information in this thread. Anyone who says one is better than the other without carefully qualifying the situation is giving a misleading answer and should not be considered a credible source on the subject. One is not better than the other in all situations.

To those who keep talking about how much better water is as a cooling media than air I say this. Clearly for a given size an air to water exchanger alone is better at transfering heat than an air to air; however, what we are talking about here is a system. One is air to air. The other is often AIR TO WATER TO AIR.

For a boat owner with an endless supply of ambient water the choice is clear. For the drag racer with enough ice to last the race the choice is clear. For many other situations it can be a difficult choice.

Also I hate the use of the word efficient here. A word like effective should be used to sum up cost, wieght, dynamic efficiency, steady state efficiency, packaging, etc.

 

Hi Mike

Not rub you the wrong way but you sound like a
salesmen not an engineer.

So what do you think is going to take the heat off the
water'¦'¦'¦. AIR.

Now if you load your tank up with ice there's no beating
an A2W IC.

BUT if you have the room for a properly sized A2A IC there's beating it.

So let me get this write, you'll take the heat out of the air
pass it threw the aluminum into the water out of the water back into the aluminum so the ambient air can
take it back out of the aluminum.

It's like a bad rumor, the more it gets passed around the worse it gets.

The only reason the OE's use A2W is for packaging reasons, that's it.


Sorry Mike, I,m not trying to make look bad.

Chris

 

A great analogy, but I'm afraid it just doesn't hold water (no pun inteneded ). There are far to many variables for it to be that cut and dry.

For short term use, an air to water can't be beat...and I don't think anyone is arguing that. For long term use, the air to water becomes a detriment as the water will heatsoak the heat exchanger and deem it useless. All the while, the lowly air to air cooler continues cooling as it always has...without nearly the amount of that nasty heasoak that plauges the air-water setups.

 

Yea, well. . . when I start spouting off about specific heats, Mdot delta T's, and Log Mean Temperature Differences, then people get mad too.

Sure, but it has a longer period of time to do it. What the water offers is a very high heat extraction rate. If you want to take the maximum amount of heat possible out of the pressurized air for a short period of time (if I stay in it more than 10 seconds, then I'm going 150 mph), then water is the way to do it. You can dissipate the heat later.

That's correct on the surface, but you took out the time factor. As stated above, you can very rapidly remove alot of heat from the pressurized air with water, store the heat in the water, then dissipate it over time. You can not remove heat as rapidly with air and there is no appreciable system capacitance.

Is that why they cool the engine using water also?

Mike

 

There has got to be a back to back mag test out there some ware
to give these guys some data to draw from.

 

If you have an woefully undersized water reservoir or a woefully undersized radiator, then you are correct. I have a very small radiator, but large reservoir. I've made numerous back-to-back dyno, track, and street full-throttle runs and the water never got over luke warm. I feel the need to remind you that 100 deg water will still remove heat more rapidly than 75 deg air when we're talking about 200+ deg boost temperatures.

My experience has been the opposite. Make a few back-to-back full throttle street pulls with an air/air, then check the core temp. I guarantee you that my water is cooler after the same abuse.

Mike

 

Yes, but you have to keep in mind the original intent of the post...road racing. Were not talking about a couple of back to back dragstrip runs here...or even hot lapping it a half a dozen times. Road racing is far more strenious on all parts of the vehicle and heat is a very big issue...even for stock engine radiators. It's not a matter of a "woefully undersized radiator", but rather the need for a woefully oversized one to compensate for the amount of heatsoak your going to run into. I'd venture to say that 100 degree water on a road coarse would quickly turn into 150 + degree water....at which point again, that lowly air to air unit starts looking like an artic blast.

 

Where can we find more info? Books or sites etc.... I am looking for the math behind the topic.

If you do not want to post that type of info here feel free to pm me, or put a message on my linux server http://enyawix.selfip.net/mustangs/

 

All the calculations are well established, but the problem is that you need to get to the 3rd year of engineering to be taught them. A water/air intercooler system is a pretty complicated system analysis.

Mike

 

I am close to a BS. in computer science. Math is not an issue for me. I have changed my major so many times I bet I have more credits than you do.

 

Look what I found!


http://www.bellintercoolers.com/pages/techFAQ.html#FAQ_5




How can an air-to-air intercooler be more efficient than a water based intercooler?
There is an overwhelming quantity of ambient air available to cool an air-to-air core relative to the charge air thru the inside of the intercooler (The iced down water intercooler is the only exception to this argument.). At just 60 mph, with a 300 bhp engine at full tilt, the ambient air available to cool the intercooler is about ten times the amount of charge air needed to make the 300 hp. Whereas the water intercooler largely stores the heat in the water until off throttle allows a reverse exchange. Some heat is expelled from a front water cooler, but the temperature difference between the water and ambient air is not large enough to drive out much heat. Another way to view the situation is that ultimately the heat removed from the air charge must go into the atmosphere regardless of whether it's from an air intercooler or a water based intercooler. The problem with the water intercooler is that the heat has more barriers to cross to reach the atmosphere than the air intercooler. Like it or not, each barrier represents a resistance to the transfer of heat. The net result; more barriers, less heat transfer.




What ranges of efficiency can be expected from an intercooler?
A typical air-to-air intercooler for a street application achieves between 60% and 70% efficiency, an excellent/optimum design for road racing can approach close to 90% efficiency, but requires an adequate "budget!'

Typically, a liquid-to-air intercooler achieves higher efficiencies than an air-to-air intercooler, starting at 75% efficiency and reaching peaks of 95% efficiency. Another advantage is the optional use of ice as a coolant, which is the only way to reduce the charge-air temperature below the ambient air temperature.
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