# air to air vs air to water. Pros/Cons (searched)



## bakana (Sep 18, 2005)

I wanna hear some opinions, personal use responses. This setup will be for a daily driven 1.8t running a maximun 30 PSIG daily. If anyone has IAT numbers of there setups that would help greatly. Thanks


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## bakana (Sep 18, 2005)

*Re: air to air vs air to water. Pros/Cons (bakana)*

Or not LOL


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## kevhayward (Mar 13, 2007)

*Re: air to air vs air to water. Pros/Cons (bakana)*

Been covered many times before and it usually sparks an A-W v A - A debate, as per Standalone v Standard, 3" v 2.5" etc etc.








I don't mind sharing my experiences though








I have both 1.8T and VRT dailys. Air-Water on the VRT and Air - air on the 1.8T.
I like both setups. The air-air setup has higher average IATs, but it's not a very big intercooler. The VRT's A-W system is massively over engineered and temps are never an issue. Always 5 - 10 deg C above atmosphere. Even on the dyno for 2 hours with no fan air blowing over the pre-rad, IATs never exceeded 50.
IATs on the 1.8T are usually 12 - 18 above atmos.
I see some people claim "below atmos IATs", but I don't see how that is possible on a roasting motor that's been used for a couple of hours and without some kind of refrigeration system? I dunno, I'm waiting to be educated








In summary, A-W is more efficient if spec'd to the engine correctly. After all, pouring cold water onto hot metal is always going to be more effective than blowing on it. But for many people a larger FMIC is easier, cheaper, lighter and does the job http://****************.com/smile/emthup.gif . 
You pays your money and takes your choice....


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## bakana (Sep 18, 2005)

*Re: air to air vs air to water. Pros/Cons (kevhayward)*

I searched but didnt find anything but for sale stuff. Now that I think of it though I didnt do archieved posts. Ill have to go back and check.
Your input has been very helpful. Thanks. Ive read online people see below atmo when ice is added to the resevoir tank. I also read air to air gets consistant IATs more so than an air to water because the water will eventually get to a set temp during prolonged use. I dont think that is ture if setup is installed correctly like you stated. 
Whats funny is overall its acctually cheaper to run air to water if you know what your doing


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## CDJetta (May 11, 2004)

*Re: air to air vs air to water. Pros/Cons (bakana)*

No it's not. a/a setups cost only hundreds. Maybe 400 bucks max? Depends on how much your core costs.
For my a/w setup that I've made for my vrt. Core = 200, pump = 200, heat exchanger = 100, Copper+rubber lines = 100, piping = 50, fittings = 50, misc wiring +fuse+relay for pump = 30, water resevoir = 150.
That's easily 800-900 bucks. I went overkill on my water pump but I wanted it to last and flow a crap ton of water and have it variable so I could set it's flow and increase it's system pressure to dial in the efficiency. Copper tubing isn't neccessary but running rubber hoses for the whole thing wouldn't be advisable for reliability. Your water resevoir you can cheap out for 50 bucks maybe but a nice tank that fits in your car nicely and looks good will cost you 150+.
My a/w core is a ebay core too.... not even a expensive brand one so if you go with a ebay a/a core then you're only looking at 300 bucks or so for everyting on a a/a setup.


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## kevhayward (Mar 13, 2007)

*Re: air to air vs air to water. Pros/Cons (bakana)*


_Quote, originally posted by *bakana* »_Your input has been very helpful. Thanks. Ive read online people see below atmo when ice is added to the resevoir tank. I also read air to air gets consistant IATs more so than an air to water because the water will eventually get to a set temp during prolonged use. I dont think that is ture if setup is installed correctly like you stated. 
 
No probs!
Agreed, Ice would certainly get your IATs down, but it's only a short term burst! The way I see it, if IATs were constantly lower than ambient, then there should be a lot of condensation on the intake manifold after an hour's ride? But I've never seen that on any boosted VRTs, or 1.8Ts








It's the AW setups with inadequate water reserves that over heat.
I've seen some really dire setups. One was so bad that from cold, it took just 10 seconds of boost in 3rd to get IATs to 70 deg C!!
If there is enough water and the radiator is big enough, then it's never a problem. 

_Quote, originally posted by *bakana* »_
Whats funny is overall its acctually cheaper to run air to water if you know what your doing









It can be, but my Schimmel AW setup was far from cheap







Well worth the cash though as it's been great.


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## rickyrunamuk (Sep 13, 2004)

On tues I was at kinetic to do some tuning on my vrt with its unfinished awic ( no coolint in the system yet) shawn and I went for a twenty minute drive to do some data logging and tweaking did a few full boost runs as well.when we got back to the shop the ic was cool to the touch! in no small part due I'm sure to a true under the car cold air intake and hood louvres directly above the ic.


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## slc92 (Feb 9, 2005)

*Re: (rickyrunamuk)*

My A/A was about ~$300-$350 all in. That's core, piping, all silicone couplers, and T-bolt clamps. Cheap and simple. 
I would only consider A/W for two applications. It might actually justify it's much higher cost and complexity. 
1) Drag car. Filling the resevoir w/ ice should yield some gains.
2) There is no space for an A/A.
Other than that, I don't see why you would go A/W.


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## CDJetta (May 11, 2004)

*Re: (slc92)*

Stealth? You can paint the a/a core but sometimes with fitment you can't really hide the huge things that's sticking out there or the piping.


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## kevhayward (Mar 13, 2007)

*Re: (slc92)*


_Quote, originally posted by *slc92* »_My A/A was about ~$300-$350 all in. That's core, piping, all silicone couplers, and T-bolt clamps. Cheap and simple. 
I would only consider A/W for two applications. It might actually justify it's much higher cost and complexity. 
1) Drag car. Filling the resevoir w/ ice should yield some gains.
2) There is no space for an A/A.
Other than that, I don't see why you would go A/W.


It's not about should, would or why though is it? It's about personal preference.
Having a Corrado yourself, you should know only too well about reason 2. I for one was not prepared to hack up my Corrado's front panel and bumper, compromising impact saftey, for the sake of an A/A cooler. And I certainly wasn't going to entertain hanging an IC off the gearbox VF style, which is pants.
I also wanted the shortest boost path with the least pressure drop as possible.
Complex? There's nothing complex about pumping water. It's simple plumbing.


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## crzygreek (Jul 8, 2005)

honestly i'm in the midst of this decision and i would love to go a/w because there is no space in this damn car... but 1775US + tax and ship... thats absolutely absurd. If it was 1400~ shipped then ok but anyways. I'll be watching this thread!


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## rickyrunamuk (Sep 13, 2004)

Ive pieced my whole awic setup for under $300.00. Ebay ic, $80.00, one 2.5 inch ubend exhaust tubing for charge pipe $30.00, used polaris quad radiator for heat xchanger $30.00, qty. 2 x5/8 garden hose $25.00, used bilge pump free, misc silicone couplers , hose barbs and clamps $120.00


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## CDJetta (May 11, 2004)

*Re: (rickyrunamuk)*

Not saying you can't put it together for cheap but to put together a nice decent setup you are looking at 800 bucks or so with a good properly flowing pump that will last a long time. Not a plastic one that comes in those cheap a/w kits that you see out there. The VR6/F-150 Lightening pumps, in my opinion, don't flow enough.


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## kevhayward (Mar 13, 2007)

Agreed /\
You have to see an AW setup like Schimmel's to appreciate how good a good one is and how bad a bad one is.


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## slc92 (Feb 9, 2005)

*Re: (kevhayward)*


_Quote, originally posted by *kevhayward* »_
It's not about should, would or why though is it? It's about personal preference.
Having a Corrado yourself, you should know only too well about reason 2. I for one was not prepared to hack up my Corrado's front panel and bumper, compromising impact saftey, for the sake of an A/A cooler. And I certainly wasn't going to entertain hanging an IC off the gearbox VF style, which is pants.
I also wanted the shortest boost path with the least pressure drop as possible.
Complex? There's nothing complex about pumping water. It's simple plumbing.


It is more complex than an A/A setup. That's a fact. Two heat exchangers, a pump, water lines running to the rear of the car, a resevoir. More complex, more expensive, that's why most OE cars come A/A.
I don't have A/C so A/A wasn't bad at all. Tow hooks, couple tabs, and the bottom 6 in. of the upper rad support are the only things that were cut. No safety or appearance was compromised.


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## bulldogger72 (Mar 16, 2008)

*Re: (slc92)*

you can make an awic system as complex or as simple as you like.


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## crzygreek (Jul 8, 2005)

honestly, i'm really liking the idea.. maybe we can talk to schimmel and get a gb going for a more affordable price?


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## Yareka (Mar 5, 2002)

*Re: (crzygreek)*

The performance of each could be argued forever and it really comes down to how much thought you put into an a/w setup that makes the difference. Efficient exchangers, system volume, and proper size core can keep iats just as good as a/a.
But the real advantage of a/a is the fact that you dont need to run big piping in and out of the bumper, instead you only need to run hose feeding the exchanger which really helps in a tight bay. Another advantage is the length of piping for a/w is usually 1/3rd of what you would use for a/a so the charge route is way more efficient.


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## kevhayward (Mar 13, 2007)

*Re: (slc92)*


_Quote, originally posted by *slc92* »_
It is more complex than an A/A setup. That's a fact. Two heat exchangers, a pump, water lines running to the rear of the car, a resevoir. More complex, more expensive, that's why most OE cars come A/A.
I don't have A/C so A/A wasn't bad at all. Tow hooks, couple tabs, and the bottom 6 in. of the upper rad support are the only things that were cut. No safety or appearance was compromised.


Some of us enjoy the engineering involved with AW setups. We see a nice project rather than complication.
Some OE cars use A/A because it's cheaper and easier to implement, but not necessarily better.
A number of OE cars came with AW from the factory, including the Jaguar XKR, Lotus Espirit turbo, Mercedes SL55 to name but a few.
There is more to fitting a proper sized A/A intercooler in a Corrado than you suggest. I've been there. So if you cut your tow eyes off, that's really useful in the event of a break down isn't it. My AW setup required absolutely no bumper or front panel surgery what so ever. The pipe work is massively shorter and the boost drop much lower. I think I know which is going to have the better throttle response.
I thank you.


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## slc92 (Feb 9, 2005)

*Re: (kevhayward)*

^^
1) You don't need tow hooks to get a car on a flat bed.
2) Arguing on the internet is for idiots w/ too much time on their hands so you can have the last word.
Bottom Line: Add in the cost of an SRI and A/W is ALOT more $$ than A/A. I can make as much power as I wan't w/ A/A and the $1-$3k can be better spent somewhere else IMO. If your rich or don't wan't to trim anything in the front end then knock yourself out.








I think my entire turbo setup cost less than Schimmels SRI and A/W setup. 



_Modified by slc92 at 6:34 PM 9-26-2008_


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## magicdave (Sep 27, 2008)

*Re: (kevhayward)*

How do chaps!
I've been reading this forum for what seems like years and years, on the advice of my mechanic who continually hopes that some of the knowledge will rub off on me, but I've never posted a thing; however this is the first time that I've felt compelled to sign up and say anything as it matched my situation so perfectly a little while ago. As a warning, I'm not all that technical. I understand concepts, and I can read wikipedia as well as any other professional geek, but as for actually doing work on the cars I've had, well... I tried to replace a bulb in one of my cars (Mk2 pre conversion) and broke two bulbs and the front panel doing it, and still didn't manage to make it work without help.
To try and explain why I've picked up on this particular thread to make my existence known, in the last 15 years I've owned (amongst others) the following cars, in no particular order:
2 x Jaguar XKR (still got 1!)
1991 Esprit Turbo SE in hideous yellow (I still ask myself why yellow, and still don't know)
Mk1 1.6 GTi
Mk2 1.8 16v GTi that became a VR6 Turbo (still got!)
Caterham Roadsport (1.8 k-series VVC, bloody quick!)
Merc ML270
As you can see, I match a couple of the aforementioned cars, it was as if it was written about me! I've also (like slc92 quite rightly suggests) got way too much time on my hands, as I'm off work due to insomnia (not recommended to anyone, I'm afraid). I'm due to visit a sleep clinic in Newcastle in the not too distant future, so we'll see how that turns out. In the meantime, I've been told to watch out for incessant babbling at great length, apparently it's a side effect of sleep deprivation! So apologies for what is going to probably be an overly long post with good chunks of my life history thrown in.








I'm going to ignore the ML270. Worst car I've ever owned. All the down sides (dire brakes, crap driving position, poor off-road) to driving a merc sprinter van (which my company owns and I've borrowed for moving large bits of furniture, etc), but none of the up sides like it actually travelling in a straight line or even having a decent speed. or comfort. or visibility. or even cup holders that don't drop hot tea on you. I'm also not going to go into detail on the Caterham (which was awesome until I crashed it and put myself into hospital for two months) or the Mk1 GTi (which was a fabulous car and I wish I'd never sold it) as they're not too relevant to this.
So let's crack on with the Esprit. I had it for a total of four months, during which time it spent three months in a workshop being fixed for one of numerous reasons, and three weeks in a bodyshop after some clown reversed into it.
Awesome car to look at, and feels perfect for that one single occasion when you can actually drive it. But you get really, *really* bored of poor reliability. I'm sure the brits (and maybe others) on here will be aware of Jeremy Clarkson's problems with the Ford GT he had. Mine were similar. I can't recall completing a single journey in that car without assistance from either the AA or my helpful local Lotus expert.
Honestly, if you think rovers have a tendency to overheat, then you should give one of these babies a go. Guess what was blamed for the overheating? Me! They blamed me for driving too hard. I pointed out that it was supposed to be driven hard, surely!? Turns out that one of those subconscious things that people do when the performance of cars drops off is push the pedal more. Lottie's (it did indeed have a name, Lottie the Lotus, obviously) performance would drop over time spent driving it and I was just pushing it harder to make up for it. Cue overheating problems.
I decided to give up with the car, and on one rare occasion when it was running under it's own steam (steam of course being the operative word every other time), I managed to sell it. Don't buy a yellow esprit, just in case it's the same car. Chances are it's for sale somewhere right now, if it hasn't been torched by it's somewhat forlorn owner.
The Jags. Lovely cars. Beautiful design. Don't like the new ones, look too flash, not elegant enough, just not what a jag should be. Anyway, I digress - the old ones at least give a fantastic sense of power all of the way around the clock (to the limited 155mph, uh, tested on german autobahns of course







) 0-60 in just over five seconds every time because of a good auto box, which is normally a contradiction in terms, but that's probably because it's actually a Mercedes device that jaguar bought off them as theirs were all rubbish.
First one I had popped a hose first time I took it near track. But not before performance /severely/ dropped off as soon as it was properly warm. Which is a damn shame, as the CATS active suspension works -beautifully-. And I mean, it is a work of art - how you can make something quite that heavy so graceful around corners is beyond me. That's one of the reasons I've got one now, but don't take it on track. The current jag is now the daily driver as my commute is oh, five miles or so a day (when I'm not working from home or ill, of course!) and therefore doesn't chew through fuel all that badly - though I suppose I could get a pushbike, but where would the fun in that be?








The Mk2 VR6T. My ever patient and now absurdly rich-with-my-money mechanic completed the conversion on this little beauty a little while ago. It's a wolf in sheep's clothing, mostly as the paint is buggered on it which makes it more appealing as a stealthy car in my eyes. It's not been on the rollers or anything like that because I don't see the point - it's been tuned on the road and track as that's where it is used, rather than in someone's shed with some rollers in it. I say this as I'm not able to give you any idea of the power output; frankly I don't know, I like it, it works on track, and it truly is a stunning example of an engine that should have been turbo charged as standard, emissions and tax be damned. What I'd like to say here is that it's reliable, and it's as you chaps refer to it: A/A. It's got a huge intercooler on the bugger that only sticks out a little, and it works really, really well. My mechanic chap had chosen to do it in A/A rather than A/W because it's simpler and wasn't going to cost me anywhere near as much money to do - nice that he was considering my bank balance for once. Kind soul.
The other thing he did do on the car is fit some gizmo that squirts cooling water onto the intercooler as it's going along on a little switch - something the aforementioned mechanic put together when he wasn't off drinking champagne, eating caviar and paying off top rate hookers with cocaine and other goods bought with my hard earned cash. I guess that'd be A/A+W? Anyway, apparently that was something quite a simple thing but it makes a difference; I've ran out of water before, and the performance isn't as sharp, somehow. Could be psychosomatic, but I don't know these things; I just keep the bottle topped up now.
Anyway, to summarise what I'm trying to say:
Just because cars come from the factory charge cooled, doesn't mean it's a good thing. As far as I can tell it's been done on cars that they don't think will be driven hard or don't have to be reliable. It's my personal viewpoint that it was done that way on the lotus because that's what they had lying around. Just like the rear lights from toyota's parts bin.
I'm sure that aftermarket designs for charge coolers or whatever are better - they can't be any worse that the OEM ones.
Oh, and of all of the times that my Esprit was recovered, I don't remember towing eyes ever being used to load it onto the yellow flatbed trucks that took to me around in droves, baying for position like a pack of hungry wolves stalking a bleeding hare. And on the subject of throttle response, the jags aren't very good at that. The lotus was alright, but I think that was down to the engine. And of all of the forced induction cars I've owned, this mk2 vr6 turbo has the best throttle response of them all.
Anyway, I'm sure this will provoke a response. That wasn't my intention; I just want people to be aware of my experiences. I'll probably now drift back into the background and go back to reading but I could potentially show up again, you never know.








Nonono, thank *YOU*!








Dave (Magic)


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## MA_XXX (Apr 10, 2002)

*Re: (magicdave)*

i used an AWIC for my ABA 16VG60. i made everything including the waterjackets for the core and the endtanks. i used a bunch of things that were readily available but not matched very well to the engine.
IF i did it again... i would make things alot bigger and more robust. it worked but, not well enough for my liking. let's just say i've learned from my experience.


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## CDJetta (May 11, 2004)

*Re: (MA_XXX)*

My new A/W core isn't an ebay core. I've over done my a/w setup and hopefully it will be in use by beginning of next year in my Quattro Jetta I'm slowly working on.
The new core is a PWR, then the Jabsco marine pump, some small car radiator that I found, and a 5 gallon tank. I might swap out the radiator for 2-3 transmission coolers. Most transmission oil coolers I've found are all copper and have very good fins and what not. Seems like they'd get closer to ambient temp than a regular radiator. I'll probably also get 2 small ones before it returns to the tank and then one small one before it goes into the core. The small one before the core will have a nitrous/CO2 spray on it to get below ambient temps when racing.


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## Issam Abed (Feb 12, 2004)

*Re: air to air vs air to water. Pros/Cons (kevhayward)*


_Quote, originally posted by *kevhayward* »_
I see some people claim "below atmos IATs", but I don't see how that is possible on a roasting motor that's been used for a couple of hours and without some kind of refrigeration system? 

I have seen "below atmos IATs" but with serious freezing/cooling externally of the core itself.
I really do not have a preference as both do there job well.
Has anyone SUCCESSFULLY tried both?


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## [email protected] (Jul 2, 2006)

*Re: air to air vs air to water. Pros/Cons (Wizard-of-OD)*


_Quote, originally posted by *Wizard-of-OD* »_
I have seen "below atmos IATs" but with serious freezing/cooling externally of the core itself.
I really do not have a preference as both do there job well.
Has anyone SUCCESSFULLY tried both?









madtech.se









ATA/WTA FMIC


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## Issam Abed (Feb 12, 2004)

*Re: air to air vs air to water. Pros/Cons ([email protected])*


_Quote, originally posted by *[email protected]* »_








madtech.se

Jesus christ!
















The good thing about 034 is that I can have 2 air temperature sensors.1 pre intercooler and 1 post intercooler.Would love to see the drop in temperature of this set up compared to a full air to air.


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## CDJetta (May 11, 2004)

*Re: air to air vs air to water. Pros/Cons (Wizard-of-OD)*

i dont' see the use in having two. If you have a a/w running at max efficiency... then it's not gunna get any more efficient running with an extra a/a.
You can't get below ambient unless using some sort of extra cooling methods like nitrous spray, CO2 spray, Ice, or freon/r-134 a/c mocking up.
I'd like to see a properly setup a/c setup. Somebody runs a compressor and refrigerant through an intercooler to cool the air. I dunno if a stock compressor off a car could take the cooling but it's be worth a looking into.


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## crzygreek (Jul 8, 2005)

the only thing im worried about with the a/w intercooler is heatsoak. Has anyone experienced heatsoak with the water to air?


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## [email protected] (Jul 2, 2006)

*Re: air to air vs air to water. Pros/Cons (CDJetta)*


_Quote, originally posted by *CDJetta* »_i dont' see the use in having two. If you have a a/w running at max efficiency... then it's not gunna get any more efficient running with an extra a/a.
You can't get below ambient unless using some sort of extra cooling methods like nitrous spray, CO2 spray, Ice, or freon/r-134 a/c mocking up.
I'd like to see a properly setup a/c setup. Somebody runs a compressor and refrigerant through an intercooler to cool the air. I dunno if a stock compressor off a car could take the cooling but it's be worth a looking into.

WTA is only good with ice prep
With just water and standing still it sucks as bad as ATA standing still at the track
But a nice como is perfect for drag strip.
But 2500$ for a real system with a good race cooling core is way to much


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## seL (Jun 8, 2004)

*Re: air to air vs air to water. Pros/Cons ([email protected])*

My a/w setup utilizes an a/c condenser instead of a rad and my tank is built right into (or around) the intercooler itself. The lines run down to the pump with is mounted on the side of the tranny...everything up front right there. Temps are great, the cooler is actually ice cold to the touch when the car has been running/driving.


















_Modified by seL at 8:08 AM 9-27-2008_


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## bulldogger72 (Mar 16, 2008)

*Re: air to air vs air to water. Pros/Cons ([email protected])*


_Quote, originally posted by *[email protected]* »_
WTA is only good with ice prep
With just water and standing still it sucks as bad as ATA standing still at the track



false. water is a better medium than air for transitioning heat,even standing still. you cant deny thermaldynamics.
i have used awic's in NON drag racing events, no ice bath,inlet pipe to the awic-hot, intake manifold still ~cold~ to the touch after 6 minute run.
it comes down to a properly designed system, w/ an ample resevior, quality heat exchanger, and GOOD core.


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## [email protected] (Jul 2, 2006)

*Re: air to air vs air to water. Pros/Cons (bulldogger72)*


_Quote, originally posted by *bulldogger72* »_

false. water is a better medium than air for transitioning heat,even standing still. you cant deny thermaldynamics.
i have used awic's in NON drag racing events, no ice bath,inlet pipe to the awic-hot, intake manifold still ~cold~ to the touch after 6 minute run.
it comes down to a properly designed system, w/ an ample resevior, quality heat exchanger, and GOOD core.


yes but even my ATA keep the pressure pipes and plenum ice cold.
As long as you run the car both system dont have any advantage IRL.
But ice prep on a hot day at the dragstrip is way supperior.
Sad thing is that 99.9% of all wta´s have such small cores so that they get a flow restriction instead.
keeping a good 3inch hole for 500hp is a huge WTA core to mount under the hood


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## storx (Dec 6, 2006)

there is a guy that runs a Twin Turbo Mustang at the track here localy and his setup is pretty cool. Instead of having a huge resovoir sitting under the hood collecting heat and making everything around it hot he ran copper under the car from the front to the back on both passenger and driver side secured to the frame well... i think he said it was like 60 feet total of copper pipe 1 inch in diameter going to the heat exchanger on the front of the car through a 1 inch clearwater pump from harbor frieght. there is flex hose that went from the solid copper under the car to the heat exchanger to take the movement of the car when it is driving. He said that when he ran the copper pipe under the car the air rushing past it while driving drops the temp from when it leaves the heat exchanger to the A t W core. he has 3 temp gauges and 2 water pumps hooked up and the 2nd one is setup were if the water pressure form the first one drops below 30psi that the second one comes on and beeps to let him know there something wrong. his examples was he would get 170 degree temps coming from the A t W core to the heat exchanger coming out of the exchanger around 100-110 degrees and then dropping on average about 5-10 degrees more thru the copper pipes under the car before going back into the core on a 90 degree day. 


_Modified by storx at 10:46 AM 9-27-2008_


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## leebro61 (Nov 7, 2001)

*Re: air to air vs air to water. Pros/Cons (bulldogger72)*


_Quote, originally posted by *bulldogger72* »_
false. water is a better medium than air for transitioning heat,even standing still. you cant deny thermaldynamics.


To expand slightly on this without getting too nerdy... each fluid in the exchanger has a certain "heat capacity". The heat capacity is the product of the fluid mass flow rate and it's constant pressure specific heat (m*Cp). The MAXIMUM heat that can be exchanged is then the product of the SMALLER of the two heat capacities and the inlet temperature differential (Thot_inlet - Tcold_inlet). The Cp of water is ~4 times that of air, meaning that for 75% less mass flow, water can extract the ~same amount of heat.
The advantage to an air/water setup is that you have control over the heat capacity of the cooling fluid because you can control both the mass flow rate and the specific heat (by changing the fluid). Also, you can change the inlet temperature differential by reducing Tcold_inlet (add ice, etc.). In an air/air setup, the cooling flow rate is basically a function of your intercooler size and how fast you are driving. Tcold_inlet is also fixed by ambient conditions.
I guess what I'm trying to say is that a well setup air/water setup has the capability to outperform an air/air setup because the driving force of heat transfer can be controlled by the person setting up the system.


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## slc92 (Feb 9, 2005)

*Re: air to air vs air to water. Pros/Cons (leebro61)*

I'm not an engineering major so a couple questions.
With A/A your fluid(air) is essentially limitless.
With A/W you have only what's in your system. While it may be more effective at removing heat, what happens when the water becomes hotter than the ambient air. Even in an efficient system the water eventually has to become hotter than the air flowing over it's heat exchanger unless you are adding ice to the resevoir. Couldn't this potentially make it less effective than an A/A after a period of time(track day, extended street driving)? 
Anyone do track days? I would be curious to know what IAT's are for both setups on similar cars.


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## CDJetta (May 11, 2004)

*Re: air to air vs air to water. Pros/Cons (slc92)*

Water is better at soaking up and dissipating heat than air. So.... it not only takes in the heat from the charge better but it also distributes more heat into the heat exchanger better which makes it get closer to ambient temp, if not to ambient temp if the heat exchanger is sized properly. It all depends on the efficiency of the build. If the heat exchanger is robust enough to dissipate all the heat it takes in and get down to or very veyr near ambient temp. You can also change the flow characteristics of your a/w setup with bigger/better components unlike a a/a. With a/a all you have is your core and the air. With a/w you can flow more water if need be, up the pressure at which the water is run at, change the fluid in the system that has a better heat soak efficiency, I think Methanol would work great, and you can change the size of the heat exchanger in order to cool down your fluid better.


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## slc92 (Feb 9, 2005)

*Re: air to air vs air to water. Pros/Cons (CDJetta)*

Thanks for the reply. I do understand all of that. I'm just making the point that the temp of the ambient air flowing over the A/A on a 50 degree day will always be 50 degrees. The water/fluid will eventually be hotter than that.


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## CDJetta (May 11, 2004)

*Re: air to air vs air to water. Pros/Cons (slc92)*

yeah but if the water can get down to 51-52 degrees and the water is able to transfer more heat out than the a/a at 50 degree ambient the a/w is still gunna be better because of the higher efficiency.


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## adam12er (Sep 6, 2002)

*Re: air to air vs air to water. Pros/Cons (CDJetta)*

I think for street use I would probably go with a nice A/A set-up. Easy to use, no worries about pumps (or forgetting to turn pumps on) etc.
For the strip, however, I feel A/W is king! And, as far as price...well we use a cooler, a bilge pump from Bass Pro Shop, some rubber hose, and an intercooler from a Typhoon (Garrett). Total price under $100. We see intake temps below ambient temp. (we use ice water - 1 bag of ice = 2 runs) The car makes 480whp and runs low 10's.
Good luck though, 30psi sounds like a bunch for daily street use


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## slc92 (Feb 9, 2005)

*Re: air to air vs air to water. Pros/Cons (CDJetta)*


_Quote, originally posted by *CDJetta* »_yeah but if the water can get down to 51-52 degrees and the water is able to transfer more heat out than the a/a at 50 degree ambient the a/w is still gunna be better because of the higher efficiency.

I agree. We are generalizing though. I'm sure it would depend on the specifics of each setup. 
Nothing wrong with a nice A/W setup. Especially if fittment of an A/A is an issue. 
Performance wise I always look at cost-benefit since like most of us, I'm not rich and money is limited. Save here, spend somewhere else kind of thing. When I look at it that way, I can't justify an SRI and A/W for a street/strip car. I can run 11's at the track, have a ball on the street, and make well over 400whp reliably w/ a stock manifold and a ~$300 a/a setup. Add up the A/W setup, fans, SRI, fuel rail, etc. For what most people on here do with their cars I just don't think it's cost-performance effective. That's just the way I look at it.


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