Lextreme II
Active Member
Ok,
Experts please teach us why A2A is better than W2A or other way around.
Experts please teach us why A2A is better than W2A or other way around.
Air to Air or Water to Air (Round 1)
- Thread starter Lextreme II
- Start date
The 1UZFE EGR Delete Kit is available for sale here.
I disagree, I have a large a2a cooler fitted to my car and have painted it matt black, it is now virtually invisable.
I think it is wrong to stereo type peoples decisions on a2a or w2a to something as pathetic as bling.
It seems that most people are aware of the positives/negatives of either system and use those points to decide either way.
Your argument is stronger without comments such as this.
Nothing personal Zuffen I just think such comments are aimed more at irritating certain people than having a healthy discussion.
Just my opinion
Cheers
Trev
I took a look at the pics.
http://homepages.tig.com.au/~robs/ic2a.jpg
How is this a better cooler than air to air? Won't the temperature of the water be the same as the ambient air and thus there would be no improvement in a temperature gradient and thus no gain in heat conduction?
The only logical reason for water that I can imagine is that water has a greater heat capacity. And if for some reason flow within the intercooler is slow enough, water would be an advantage.
However, as people mentioned in another thread that the pressure drop can be minimized within the IC and since there is an almost infinite amount of cool ambient air, water cooling in regards to a street car has minimal advantages over air cooling.
The stats I posted in the other thread were from the turbonetics catalouge and were for a 4l engine and 10-15psi of boost.
If you work out the volume of air going into the motor at 6000rpm and 15psi and 90% engine efficiency then its .36 cubic metres per sec. If you take one of the typical 600mmx300mm intercoolers and work out the speed you need to be going to pass .36 m3 of air through the intercooler its only 7.2 km/h. You only have to be travelling at 7.2 km/h to significantly drop the charge air temp. The intercooler will not heat up on boost, off boost or any other time apart from being at a stop.
Trvln,
80% efficiency is pretty good. What size engine was that for a weed whacker or an D9?
Anyone who talks of efficiecy of a component without telling you on what engine is selling you snake oil.
If I told you the standard 1UZ AFM was capable of supplying at least 15 times the air my engine needs would you believe me? If I run the air to my weed whacker through my AFM my statement would be 100% correct.
This is the same as saying putting a resister in circuit with your intake air temp sensor will give you 12hp. You see it all the time on eBay.
Now if I fit that on my 600cc Japanese Kia car I certainly won't get 12hp. The statement about 12hp is correct but only on a big engine.
I think you're being suckered with fancy advertising.
I agree with SC400T. A properly designed (which doesn't mean expensive or huge) W2A will outperform A2A every day of the week. The main drawback with W2A on the race track is weight.
80% efficiency is pretty good. What size engine was that for a weed whacker or an D9?
Anyone who talks of efficiecy of a component without telling you on what engine is selling you snake oil.
If I told you the standard 1UZ AFM was capable of supplying at least 15 times the air my engine needs would you believe me? If I run the air to my weed whacker through my AFM my statement would be 100% correct.
This is the same as saying putting a resister in circuit with your intake air temp sensor will give you 12hp. You see it all the time on eBay.
Now if I fit that on my 600cc Japanese Kia car I certainly won't get 12hp. The statement about 12hp is correct but only on a big engine.
I think you're being suckered with fancy advertising.
I agree with SC400T. A properly designed (which doesn't mean expensive or huge) W2A will outperform A2A every day of the week. The main drawback with W2A on the race track is weight.
I'm not an expert in automotive intercooling. I do however, have a background in industrial engines, and spent nearly 10 years with Cat & Cooper in new engine development. The environments, and intercooling applications are entirely different, and what works well for an industrial engine, probably wouldn't work well for an automotive engine.
At Cat, for our (natural) gas engines, we learned in the late-80's that the A2W aftercooling systems imported from our diesel engines didn't work as well as A2A in high ambient temperature, continuous duty applications. We simply couldn't get the charge air temps down as close to ambient when there were 2 exchanges of heat taking place. With A2A, we could typically get the charge air within 10-15 degrees of ambient, which in many applications allowed us to run the engine at higher BMEP if the gas had enough methane in it to keep the octane number above 95. This made a difference between the engine making 750 BHP or 930 BHP.
Automotive intercooling seems to be a different beast. Heat soak of the IC is a big problem, whereas it doesn't exist with an industrial engine application. Also, I would think that the fast fluctuation of charge air temperatures from an A2A aftercooler vs the more gradual change from an A2W would give the EMS more of a challenge to keep up, and wouldn't be as healthy for the motor.
My opinion, FWIW, is that although the A2W system can never achieve as low a charge air temperature as a good A2A, the smoothing effect that it has on the charge air temps will make up for it, and this is probably better for the overall health of the motor than introducing 220 degree F charge air from a heat soaked FMIC, then 10 seconds later, giving the motor 50 or 60 degree air (assuming a 40 or 50 degree ambient).
John
At Cat, for our (natural) gas engines, we learned in the late-80's that the A2W aftercooling systems imported from our diesel engines didn't work as well as A2A in high ambient temperature, continuous duty applications. We simply couldn't get the charge air temps down as close to ambient when there were 2 exchanges of heat taking place. With A2A, we could typically get the charge air within 10-15 degrees of ambient, which in many applications allowed us to run the engine at higher BMEP if the gas had enough methane in it to keep the octane number above 95. This made a difference between the engine making 750 BHP or 930 BHP.
Automotive intercooling seems to be a different beast. Heat soak of the IC is a big problem, whereas it doesn't exist with an industrial engine application. Also, I would think that the fast fluctuation of charge air temperatures from an A2A aftercooler vs the more gradual change from an A2W would give the EMS more of a challenge to keep up, and wouldn't be as healthy for the motor.
My opinion, FWIW, is that although the A2W system can never achieve as low a charge air temperature as a good A2A, the smoothing effect that it has on the charge air temps will make up for it, and this is probably better for the overall health of the motor than introducing 220 degree F charge air from a heat soaked FMIC, then 10 seconds later, giving the motor 50 or 60 degree air (assuming a 40 or 50 degree ambient).
John
Lextreme II
Active Member
Water has more cooling property than air. However, water also will take longer time to cool. We can test this out, if we have two given volume of solutions (water and air). If we put both of them in a bunsen burner. What water will take longer time to reach at a given temperature. Lets say 200 degrees F. However, once you turn off the burner, the glass with air will cool much faster than water.
How does this apply to us? Lets say both cars start driving in the morning. The W2A will have great effeciency because of water cooling property. However, after both engine warm up and reach the operating temperature, the water will not have enough time or effeciency to be cool.
Therefore, is W2A better then A2A? Depends! Long distance driving or racing, A2A is better. Short time burst like drag W2A is better.
Beside effeciency, what about other real life factors lilke:
1. Cost - An additional 3 other major parts and 4 additional water hoses
2. Complexity -
3. Installation
4. Maintaince.
5. Noise - From the electric pump
How does this apply to us? Lets say both cars start driving in the morning. The W2A will have great effeciency because of water cooling property. However, after both engine warm up and reach the operating temperature, the water will not have enough time or effeciency to be cool.
Therefore, is W2A better then A2A? Depends! Long distance driving or racing, A2A is better. Short time burst like drag W2A is better.
Beside effeciency, what about other real life factors lilke:
1. Cost - An additional 3 other major parts and 4 additional water hoses
2. Complexity -
3. Installation
4. Maintaince.
5. Noise - From the electric pump
Don't forget, there's another heat exchanger up in the front of the car that's dumping the heat of the intercooler back to atmosphere. It won't happen as fast as an A2A, but it'll happen.
The only problem is that no heat exchanger of practical dimensions can hope to get within 5 degrees of the fluid/air passing over it, so whenever you have a double exchange (A2W then W2A again) you lose 5-10 degrees in each transaction. For this reason, the W2A system won't ever get the charge air temps down as low as an A2A.
Both will heat soak if the engine idles for a long time. Obviously the A2A will heat soak a lot faster, but it will also recover a lot faster.
All your other points about cost, complexity, installation and maintenance are certainly valid strikes against the W2A.
John
The only problem is that no heat exchanger of practical dimensions can hope to get within 5 degrees of the fluid/air passing over it, so whenever you have a double exchange (A2W then W2A again) you lose 5-10 degrees in each transaction. For this reason, the W2A system won't ever get the charge air temps down as low as an A2A.
Both will heat soak if the engine idles for a long time. Obviously the A2A will heat soak a lot faster, but it will also recover a lot faster.
All your other points about cost, complexity, installation and maintenance are certainly valid strikes against the W2A.
John
A well designed W2A system won't heat up as you drive across America any more than an A2A.
Sure once you heat the water it will take longer to cool off once you stop boosting it. However you won't get the water as hot as the A2A intercooler matrix because you have a bank of cooler water running around the system.
Intake temps will rise faster in an A2A system and drop faser than a W2A system. What is overlooked is the W2A takes around 14 times longer for the Cooler matrix (the one the air is flowing over) to heat up to the same tempurature as an A2A system. If you want to charge up from the bottom of Death Valley to sea level you would have cooler charge air temps all the way with W2A whilst the A2A would slowly melt down.
There are drawbacks to W2A and David has listed them all.
As I said previously A2A is cheap and cheerful and if you're prepared to accept the shortcommings it's the system for you.
The biggest drawback I see with W2A is the lack of BLING. Where's the big FMIC that says "my car's fast" All the W2A has is a ratty radiator that looks like any other car.
Sure once you heat the water it will take longer to cool off once you stop boosting it. However you won't get the water as hot as the A2A intercooler matrix because you have a bank of cooler water running around the system.
Intake temps will rise faster in an A2A system and drop faser than a W2A system. What is overlooked is the W2A takes around 14 times longer for the Cooler matrix (the one the air is flowing over) to heat up to the same tempurature as an A2A system. If you want to charge up from the bottom of Death Valley to sea level you would have cooler charge air temps all the way with W2A whilst the A2A would slowly melt down.
There are drawbacks to W2A and David has listed them all.
As I said previously A2A is cheap and cheerful and if you're prepared to accept the shortcommings it's the system for you.
The biggest drawback I see with W2A is the lack of BLING. Where's the big FMIC that says "my car's fast" All the W2A has is a ratty radiator that looks like any other car.
W2A has reduced charge air Volume reducing LAG. there are huge benifits to W2A including the ability to artificially (ice the water for drags). you need a lot smaller heat exchanger water can conduct heat a lot quicker than Air stick you finger in hot cofee or hot air one burns the other feels hot. ( if both are at the same temperature.) for cars without large amounts of room in the front air dam or rear mount vehicles with out large amounts of air flow available near the engine.
weight is not a huge problem as it can be moved around the car to help the weight distribution.
I like W2A just to post my Vote.
have you seen PWR w2a barrel coolers? they are real nice
weight is not a huge problem as it can be moved around the car to help the weight distribution.
I like W2A just to post my Vote.
have you seen PWR w2a barrel coolers? they are real nice
urtwhistle
New Member
hey i got a little idea. its slightly related to ur topic 
has any 1 tried this , get 1 of those intake modded intake manifolds i saw a pic of on this webby. were some 1 had cut it down the center so it had a throttle body on each side. put a top mount intercooler from a wrx or evo. and have on a twin snail system a turbo push though each ic. would look pretty interesting haveing twin scoops on ya bonnet.
just an idea. could look kinda kool in therery if u could find enough room under the bonnet
has any 1 tried this , get 1 of those intake modded intake manifolds i saw a pic of on this webby. were some 1 had cut it down the center so it had a throttle body on each side. put a top mount intercooler from a wrx or evo. and have on a twin snail system a turbo push though each ic. would look pretty interesting haveing twin scoops on ya bonnet.
just an idea. could look kinda kool in therery if u could find enough room under the bonnet
Assuming that no artificial cooling method is used, in motion a w2a and a a2a should be pretty close to the same temps, assuming some time driving has happened. since the front mounted heat exhanger is still cooled by air it can not get the water colder than the ambient air. Also, since the specific heat of water is higher than that of air it will take longer for the water to cool, and, if you are using an electric pump to flow the water it will not really have the opportunity to cool down just by passing though a heat exhanger. You could get around this problem by installing an inline thermostat to stop the flow of water after the water in the intercooler has been replaced by cooler water from the heat exhanger/resevoir. I see heat buildup/soak as a potential problem for a water to air intercooler setup in a state of motion and or prolonged periods of boost (road race). And quite honestly, air temps are going to raise past ambient coming straight off the compressor housing on any turboed vehicle, there is rather hot exhaust gasses passing right by the compressor housing, not to mention that since heat does flow it will get to the compressor wheel also, so even during just a cruising state you will have higher than ambient temps flowing into the intercooler, the front mount will not get heat soaked, and the water to air may not, but it has the potential to.
mycarhasposessedme
New Member
Zuffen said:
I disagree, I have a large a2a cooler fitted to my car and have painted it matt black, it is now virtually invisable.
I think it is wrong to stereo type peoples decisions on a2a or w2a to something as pathetic as bling.
It seems that most people are aware of the positives/negatives of either system and use those points to decide either way.
Your argument is stronger without comments such as this.
Nothing personal Zuffen I just think such comments are aimed more at irritating certain people than having a healthy discussion.
Just my opinion
Cheers
Trev
Lextreme II
Active Member
The below are two examples of FMIC. They are both custom IC specifically for LS400 and SC300 with 2JZGTE swap. I will try to find some W2A IC.
Here is a FMIC SC300 With 2JZGTE Swap:
Here is my LS400 with FMIC:
Here is a good step by step installation of W2A system
Below is a Vortech after cooler which is a W2A IC.
Here is an example of heat soak
Here is a FMIC SC300 With 2JZGTE Swap:
Here is my LS400 with FMIC:
Here is a good step by step installation of W2A system
Below is a Vortech after cooler which is a W2A IC.
Here is an example of heat soak
Lextreme II
Active Member
Here is how Water to Air intercooler work:
Another W2A IC:
Another W2A IC:
Lextreme II
Active Member
Here is a jet engine i took during my Hawaii trip last week
Is that a W2A or A2A? More detail on the jet turbo http://lextreme.com/forums/showthread.php?t=2315
Is that a W2A or A2A? More detail on the jet turbo http://lextreme.com/forums/showthread.php?t=2315
Actually lextreme its just a turbocharged (very old and not efficient) piston engine. It looks like just an air to air intercooler, probably because at some of the altitudes/conditions those planes fly in the water would freeze, and I'm pretty sure ethelene glycol (antifreeze) technology wasn't the best back then.
In it's simplest form, is it not just
q = mc(delta T) ?
In regards to intercooling and maximizing heat flow, you can only play with your heat constant or temperature gradient. You can affect your heat constant by experimenting with different materials for the IC.
As for temperature gradient, I would think that water would be best for short term solutions and air to air would be best for long term. My reasoning is that the car can only hold a finite amount of water. This implies that 1) the user will eventually run out of water 2) the water reservoir will eventually equilibrate to engine temperatures. Also, won't the water be at the same temp as ambient temperature? How would someone keep the water reservoir perpetually cooler than ambient air temperature? As for air, you basically have an infinite amount of cool fresh air.
For a daily street driven car, I would choose air to air. Water to air would be an option if I were building a 6 second dragster.
And isn't there an option 3? What about the those nitrous IC coolers? That would give you a much larger temp gradient as compared to water.
P.S The above rationale is based on Thermodynamics, Fluid Dynamics and Mechanics based design courses that were taken 3 years ago and that the problem is simple laminar flow and heat exchange isolated at the interooler. My memory may be a bit hazy
q = mc(delta T) ?
In regards to intercooling and maximizing heat flow, you can only play with your heat constant or temperature gradient. You can affect your heat constant by experimenting with different materials for the IC.
As for temperature gradient, I would think that water would be best for short term solutions and air to air would be best for long term. My reasoning is that the car can only hold a finite amount of water. This implies that 1) the user will eventually run out of water 2) the water reservoir will eventually equilibrate to engine temperatures. Also, won't the water be at the same temp as ambient temperature? How would someone keep the water reservoir perpetually cooler than ambient air temperature? As for air, you basically have an infinite amount of cool fresh air.
For a daily street driven car, I would choose air to air. Water to air would be an option if I were building a 6 second dragster.
And isn't there an option 3? What about the those nitrous IC coolers? That would give you a much larger temp gradient as compared to water.
P.S The above rationale is based on Thermodynamics, Fluid Dynamics and Mechanics based design courses that were taken 3 years ago and that the problem is simple laminar flow and heat exchange isolated at the interooler. My memory may be a bit hazy
very lost: Read my post #5 and look at David's diagram in post #12. There are two exchangers and a pump in a water based intercooling scheme. One exchanger is doing A2W with the charge air, the other is doing W2A with ambient air. The water loop "shouldn't" ever get to engine bay temperature as the front mount water exchanger will be exchanging its heat with ambient air flowing over it.John
Attachments
cribbj said:
I took a look at the pics.
http://homepages.tig.com.au/~robs/ic2a.jpg
How is this a better cooler than air to air? Won't the temperature of the water be the same as the ambient air and thus there would be no improvement in a temperature gradient and thus no gain in heat conduction?
The only logical reason for water that I can imagine is that water has a greater heat capacity. And if for some reason flow within the intercooler is slow enough, water would be an advantage.
However, as people mentioned in another thread that the pressure drop can be minimized within the IC and since there is an almost infinite amount of cool ambient air, water cooling in regards to a street car has minimal advantages over air cooling.
Trvln Nalzmn
New Member
The 14 times longer comparison does not hold up. There is no closed volume of air to heat up like there is water. There is an unlimited supply of ambient air tempurature to cool the charge air.....it does not heat up and up and up.Zuffen said:
The stats I posted in the other thread were from the turbonetics catalouge and were for a 4l engine and 10-15psi of boost.
If you work out the volume of air going into the motor at 6000rpm and 15psi and 90% engine efficiency then its .36 cubic metres per sec. If you take one of the typical 600mmx300mm intercoolers and work out the speed you need to be going to pass .36 m3 of air through the intercooler its only 7.2 km/h. You only have to be travelling at 7.2 km/h to significantly drop the charge air temp. The intercooler will not heat up on boost, off boost or any other time apart from being at a stop.
