Air-to-water Intercooler Theory

[AleroB888]

Liquid to air intercoolers are where it's at in my opinion. If you look at the relatively small heat exchangers [core] compared to the cooling they provide as well as the potential to provide greater than 100% cooling (using ice) and the very small pressure drop you'll see what I mean.

You're preaching to the choir, there.

(Hey, wait a minute -- didn't you also say the "average size intercooler" didn't have significant pressure drop anyway?*....and what about extra room for the tank, hoses, pump, optional heat exchanger?.... oh well.)

To get that low pressure drop, the key is to have a large charge inlet area, with a relatively small distance from inlet side to outlet. However, in an air-to-water unit of practical size, that also means the inlet/outlet area for the water will be relatively less, and longer from inlet to outlet. That will restrict the pump somewhat. Add in some long hoses, and you may find that a pump rated at 20 GPM only gets you 5 GPM. That can be good enough, (even optimum) for medium boost, but more flow may be needed for high boost.

On my Spearco unit, up to 11 psi boost, I couldn't detect any pressure drop at all, from SC outlet to upper intake. I found restrictions upstream due to the MAF and TB to be more troublesome with the M62 kit, once boost was increased.

100 % efficiency! That sounds pretty good, what about numbers to back it up? I try to find simple and practical ways to track how the system is doing, a bottom-line approach. Therefore I monitor resultant IAT in the upper intake manifold, after the charge air gets through the entire system, recorded from the beginning to the end of a run.

I can tell you that even with iced water flowing through the core (34-40 degrees F.), it is extremely difficult on a hot day to not have the upper intake temp rise. On an average day with ambient temperature between 60 and 70 degrees F., wonderful things can happen, provided the ECT also stays reasonably low. Given those conditions, looking at previous scans, the maximum rise in intake manifold temp stayed between about 6 to 15 degrees. Only on rare occasions did the upper intake temp drop to or slightly below the starting temperature. That's with temperatures of over 250 degrees F. out of the SC, 9-12 psi boost.




*

You guys are spinning your wheels. Without specifications and qualifiers the concern over intercooler restriction is moot to minute at best. The pressure drop across the average size intercooler being used in many of the setups I've seen on forums is so small that it shouldn't be acknowledged because most are not running enough boost to make it significant.

In a system that is street legal -- with a CAT, muffler, and maybe a resonator to silence the drone -- all add up incrementally to the total back pressure, and anything that keeps even a little exhaust heat out of the combustion chamber is worthwhile.

What have you found the "average intercooler" pressure drop is? And at what boost levels? Most air-to-air units I've seen were sized for convenience, and not optimally configured as well.

On the Fiero forum there is no shortage of theoretical talk, what irritated me the most was that no one posted real time data to support what they were saying even though they were in a position to do so with their own vehicles. That's why I make it a point to post useful data from my experiences when possible, most are on the Fiero forum because for quite a while I could not get pics to post here.

Yeah, that is irritating. Why don't you do that.

[AleroB888]

Just remember you should pick your pump based around the size of hose and the over all size and volume of your intercooler, and any reservoir you may have. Just putting a higher flowing pump on doesn't necessarily mean it will get cooler. Just like in a radiator, if you pump the water through too fast, it won't have time to absorb the heat in the I/C and dissipate it in the exchanger. ie you'd only want a really high flowing pump if you had a lot of coolant volume going through a large core, where it will move more slowly than in a small core. Plus if your lines aren't big enough you'll cut down the flow from that bigger pump and just make more pressure.

The situation for a radiator and a water intercooler is reversed in that airflow cools the radiator -- the faster and cooler airflow, the better heat is transferred.

In the iced water intercooler, the more and cooler water flow, the better heat transfer. It does absolutely no harm to flow the water faster, it insures that the core will be at the lowest temperature the system will allow. That assumes there is enough iced water in the reservoir to maintain a low average temperature as the heated water makes its way back through the system.

As far as slowing down the rate of flow, where that needs to be done in the intercooler is with the charge air moving through it. That is done by increasing the charge face area, that is, the core's inlet area.

Now where you have a front heat exchanger in the water intercooler system, then there is a need to optimize the flow rate, but there we are working with above ambient temps in the system.

The diameter of the hose does affect flow rate, as does vertical height pumped, and distances pumped, but I'm not going bigger than 3/4, that's the practical limit for me.

[AleroB888]

Fenderwell mounted intercooler (circa 2010)

(Previously posted on GrandAmGT.com)


The WP136S, on (ahem) universal mounting plate:



Speaking of pumps, the washer pump went here:



Washer tank on the far end:




As expected, the new setup does run cooler in the heat of the Summer day, or I should say "less hot." At present, the IC pump is set to kick in under boost, but has a manual override "on" switch. No front heat exchanger is used in the system.

There is a slight but irritating hesitation when stabbing the pedal, and I am working on tweaking the bypass system and trying to tune it out. At present, still limited to 28 lb injectors, which are OK for high altitude use.

Side note: The Racetronix / Walbro pump has held up so far, but there is one stange thing about it: when the IAT / ECT reach the 105 / 200 range, there is a noticable change in the pump's sound, and the fuel gauge needle fluctuates instead of staying rock steady. Never loses pressure at WOT, though.

Tuning :
For the "fresh" tranny, I am using stock tables from the 2003 Alero year model, which firms things up a bit.
I added some timing in the low ranges to help with the hesitation issue. This also made more power (I'll take it) but worse traction (I'll deal with it).

Test and Tune, 6 /30 / 2010, (Bandimere Speedway, elevation 5,860 Ft., Temp. 78-88 deg. F. )

Mickey Thompson ET Street Radials, Full exhaust (no res), iced intercooler, 2.0 pulley, 9-11 lbs boost

1) 14.286 @ 95.69, 2.124 60 ft.
29 lb tire pressure, w / air filter

2) 14.217 @ 96.17, 2.095 60 ft.
27 lb tire pressure, w / air filter

3) 14.071 @ 97.08, 2.061 60 ft.
25 lb tire pressure, bypassed air filter

4) 14.076 @ 99.11, 2.087 60 ft.
24 lb tire pressure, bypassed air filter

These are better times by a tenth or so than I got previously under similar track conditions. But due to a boneheaded move on my part, the tires were not correctly balanced, and there was a lot of vibration / shaking at high speed, so I expect even better next time.

With the new IC pump, IC performance was better than expected: At the top of first gear, the IAT ( at intake manifold) actually dropped 2 degrees. By 3rd gear it rose 2 degrees, and dropped back 2 by the end of the run. (I'll let someone else figure that efficiency).

To give you an idea of how fast cars run at this track:
I thought I saw a Pontiac G6 run a 15.0x, which was good enough for me to walk across the track and check it out, expecting to see nitrous on it. When I got there, I was mistaken, it was a G8 (GT). (It did have some rims on it that looked non-stock and heavy, though.) Then there were a few new Camaros out, I saw this SS (red) run a 14.0x.......That's about right, one second slower at this track.



Note the police cruisers squared off to run at the starting line^

[Joseph Upson]

You're preaching to the choir, there.

(Hey, wait a minute -- didn't you also say the "average size intercooler" didn't have significant pressure drop anyway?*....and what about extra room for the tank, hoses, pump, optional heat exchanger?.... oh well.)

To get that low pressure drop, the key is to have a large charge inlet area, with a relatively small distance from inlet side to outlet. However, in an air-to-water unit of practical size, that also means the inlet/outlet area for the water will be relatively less, and longer from inlet to outlet. That will restrict the pump somewhat. Add in some long hoses, and you may find that a pump rated at 20 GPM only gets you 5 GPM. That can be good enough, (even optimum) for medium boost, but more flow may be needed for high boost.

On my Spearco unit, up to 11 psi boost, I couldn't detect any pressure drop at all, from SC outlet to upper intake. I found restrictions upstream due to the MAF and TB to be more troublesome with the M62 kit, once boost was increased.

100 % efficiency! That sounds pretty good, what about numbers to back it up? I try to find simple and practical ways to track how the system is doing, a bottom-line approach. Therefore I monitor resultant IAT in the upper intake manifold, after the charge air gets through the entire system, recorded from the beginning to the end of a run.

I can tell you that even with iced water flowing through the core (34-40 degrees F.), it is extremely difficult on a hot day to not have the upper intake temp rise. On an average day with ambient temperature between 60 and 70 degrees F., wonderful things can happen, provided the ECT also stays reasonably low. Given those conditions, looking at previous scans, the maximum rise in intake manifold temp stayed between about 6 to 15 degrees. Only on rare occasions did the upper intake temp drop to or slightly below the starting temperature. That's with temperatures of over 250 degrees F. out of the SC, 9-12 psi boost.




*

In a system that is street legal -- with a CAT, muffler, and maybe a resonator to silence the drone -- all add up incrementally to the total back pressure, and anything that keeps even a little exhaust heat out of the combustion chamber is worthwhile.

What have you found the "average intercooler" pressure drop is? And at what boost levels? Most air-to-air units I've seen were sized for convenience, and not optimally configured as well.



Yeah, that is irritating. Why don't you do that.

You sound a little irritated, don't be. If I've said something that conflicts with a prvious statement, sum it up to my being human and imperfect, otherwise just point it out minus the sarcasm, it has no value here anyway. Direct me to my error since it meant so much to you to point it out and I'll either fix, or clarify as so far you've said nothing to suggest indisputably that I am incorrect. I've posted quite a few datalog results regarding my experiences, just not here mainly due to a period of time where I could not get the pictures to load. Obviously you haven't seen them. I often make statements that are apt for individuals that don't need qualifiers, like the pressure drop in an intercooler being tied to the boost level.

"Most air-to-air units I've seen were sized for convenience, and not optimally configured as well."

That's pretty much what I was getting at, and I've felt the opposite of what your openning quote alleges I said. Less than optimal intercoolers plus low boost are probably not worth the trouble. My statements were made based on ratings that I have seen and my personal experiences and yes some of it falls on theory which is perfectly acceptable within reason. If you have data to show otherwise post it so we can see and learn from it rather than showing attitude that will not help any of us.

Note also that my frustration was with individuals that were in a position to show data to support what they were saying but would not. Perhaps my thinking in Fiero application terms created some discourse here as well. None the less turbo is to supercharger, what apple is to orange in some important regards. More importantly, I clearly stated this was my opinion, in an effort to avoid diatribe of this nature. When I get the system installed and tested, I'll have numbers to compare to when I used an intercooler for your benefit as well as others and if I'm proven wrong, I'll simply remove it from the car.

I'm here to share and learn, not one-up someone. Peace, no harm or ill will intended.

[timg]

I've got to say, I love A-A setups when sized and positioned properly for a street car. They're simpler, potentially lighter, and have no moving parts or fluid. Unfortunately, a lot of the A-A intercoolers I've seen are either tiny or positioned where they won't get any air flow.

A-W intercoolers are awesome for dragstrip use and for blowers with limited room for A-A systems (especially these new interchiller concepts where they use the AC system to cool the intercooler), but for street use they are one more thing requiring maintenance. I would rather not have pumps and coolant systems that could fail and then grenade my engine. Also, you have two heat exchangers to deal with (the A-W and then the W-A) rather than one.

Point being, both have their benefits and drawbacks (many, many more than I listed here). Pick the one that best suits your application. If one was always better, the OEMs would stick with it rather than jumping between A-A and A-W depending on their application.

Tim

[AleroB888]

You sound a little irritated, don't be. If I've said something that conflicts with a prvious statement, sum it up to my being human and imperfect, otherwise just point it out minus the sarcasm, it has no value here anyway.

There was no sarcasm, I agreed with you that not presenting data can be irritating.

I quoted your exact words and responded to them.

Direct me to my error since it meant so much to you to point it out and I'll either fix, or clarify as so far you've said nothing to suggest indisputably that I am incorrect.

I quoted your exact words and responded to them.

You spoke in general terms, and I responded in general terms .

........................ I often make statements that are apt for individuals that don't need qualifiers, like the pressure drop in an intercooler being tied to the boost level.

I never disputed that.

"Most air-to-air units I've seen were sized for convenience, and not optimally configured as well."

That's pretty much what I was getting at, and I've felt the opposite of what your openning quote alleges I said. Less than optimal intercoolers plus low boost are probably not worth the trouble. My statements were made based on ratings that I have seen and my personal experiences and yes some of it falls on theory which is perfectly acceptable within reason.

Again, I quoted your exact words, which are nothing like what you just said. You said pressure drop was not an issue with those intercoolers.

If you have data to show otherwise post it so we can see and learn from it rather than showing attitude that will not help any of us. Note also that my frustration was with individuals that were in a position to show data to support what they were saying but would not.

Again, you spoke in general terms, and I responded in general terms.

Now, I did use your post from another thread as a platform to launch this thread, because it seemed to display some conflicting ideas, to say the least. Sorry, but I thought it would make more interesting reading while my responses presented the drawbacks to A2W systems, which are important to mention.
As far as attitude, that's pretty subjective, your original post is here:

http://60degreev6.com/forum/showthre...241#post449241

More importantly, I clearly stated this was my opinion, in an effort to avoid diatribe of this nature. ..............

Not exactly, you said liquid-to-air intercoolers are where it's at in your opinion, and I agreed with that.

The part about the concern of pressure drop being "moot to minute" you stated as a generalized fact based on your observations, and that I disagreed with.

I also disagree further with other points made in that link by your post in the other thread, so please don't take it personal when I quote from and respond to it in this thread.

But we both like air-to-water intercoolers, so that's a good starting point.

[Joseph Upson]

There was no sarcasm, I agreed with you that not presenting data can be irritating.

I quoted your exact words and responded to them.




I quoted your exact words and responded to them.

You spoke in general terms, and I responded in general terms .



I never disputed that.



Again, I quoted your exact words, which are nothing like what you just said. You said pressure drop was not an issue with those intercoolers.



Again, you spoke in general terms, and I responded in general terms.

Now, I did use your post from another thread as a platform to launch this thread, because it seemed to display some conflicting ideas, to say the least. Sorry, but I thought it would make more interesting reading while my responses presented the drawbacks to A2W systems, which are important to mention.
As far as attitude, that's pretty subjective, your original post is here:

http://60degreev6.com/forum/showthre...241#post449241



Not exactly, you said liquid-to-air intercoolers are where it's at in your opinion, and I agreed with that.

The part about the concern of pressure drop being "moot to minute" you stated as a generalized fact based on your observations, and that I disagreed with.

I also disagree further with other points made in that link by your post in the other thread, so please don't take it personal when I quote from and respond to it in this thread.

But we both like air-to-water intercoolers, so that's a good starting point.

Point taken, I looked over what I had written and the problem is not what you quoted, its what you left out that can give an entirely different meaning to what I intended to convey. None the less, it's a good topic that I will unfortunately have little time to follow as I have the misfortune of experiencing a 6 speed failure rather than reading about one to address.

[TGP37]

I always tried to view heat like electricity and water piping. Heat will conduct well in aluminum and insulates with rubbers. Knowing this it is possible to build effective ambient cooling with zero moving parts.

Heat can be conducted just like electricity as there is the force (temp difference) and current (actual heat dissipation)

I considered a zero moving parts cooler built like this.....

Using this pipe type .......

And run that in larger pipe so air flow can be directed/forced over the fins. So it would be a pipe in a pipe. The inner pipe carries the intake air charge. The outer pipe conducts heat away. The outer pipe would route to a location where the venturi effect can be maximized, drawing the air from the vacuum created as the car moves faster.

It would be an interesting setup. If we can create equal surface area of an appropriate intercooler, we should get greater heat removal. AND the hot air is drawn out of the engine bay.

Of course I still wonder what direction of travel would be best. Conducting the cooling air in the same direction as the intake charge or opposite of each other. One would focus the cooling effect in the beginning and the other at the end.

The same idea can be used with air-water intercooling. Just use water instead of air and pipe it to a heat exchanger.

What is great about this idea is the aircharge does not have to be forced through the intercooler as the pipe itself IS the intercooler.