BicuspiD

Other than the obvious extra weight (and complexity) of this type of system, do you think using a full-size radiator make a sufficient reservoir and heat exchanger for the system? This car is mostly street driven with occasional track and autox.

While the stock FD radiator is (barely) capable of removing the heat from the entire engine, it seems it would work excellent for removing just the intake charge heat for an extended period of time, as well as functioning as a reservoir. All that would be needed is a pump/thermostat control and the proper A2W cooler - I was thinking the "barrel" style.


In a v-mount setup, especially with a proper vented hood, theres plenty of room for 2 radiators (even if you had to say use a smaller radiator), it would cut down on intake piping distance and convolutions tremendously - possibly just 2 90 degree-ish turns. Perhaps even more air could be ducted to the engine radiator - due to a shallower angle being adequate for the top a2w radiator to achieve A2A like (or better) efficiency. Plus due to the better cooling abilities of A2W and the oversized heat exchanger, it would be efficient for extended driving (the main drawback to an A2W system). Or am I all wrong in my thinking?

So weight and complexity aside - does this seem like it would be a viable alternative to a V-mount A2A setup?

sereneseven

you seem to like to do things the hard way. I really don't see the point...the system will heat soak just like an a2a set-up but with many more times the mass. the only real advantage a a2w has is the fact that it can be packed with ice yielding sub ambient intake charge for short periods of time (drag).

BicuspiD

But would it heat soak(?), considering the (relatively) small amount of heat this large exchanger is dissapating. Since water can absorb heat much more efficiently, given the ability to discharge this heat quickly via the large radiator - wouldn't you think you could keep the temps around ambient, thus all but eliminating heat soak?

mirabile

Why dont you try a S-max intercooler with CO2 injection, which also will yield the sub ambient intake temps?

NissanConvert

iTrader: (1)

Over any distance the water to air intercooler is going to heat soak like a champ. To get low(er) IAT's i just drive faster. I've been working on some empirical research and found that at about 80mph (avg) my IAT's are about 20 degrees above ambient. Of course once I heatsoak it takes time to bring them down to about 30 degrees over ambient. This is on the stock cooling system. If i park it for a few minutes i can expect to see temps 60 degrees or more over ambient because the intercooler bakes over the radiator.

Your water to air unit would do much the same, take a longer period to heat cycle, & require a great amount of ice to provide sustained cooling like an air to air unit.

I'd try to find a way to duct fresh air and use CO2, water or alcohol injection to lower your IAT's. Alternatively try the water to air and keep us posted.

Eggie

BicuspiD, you need to find KevinK2's posts about air-to-water ICs, but a quick, back-of-the-XLS calculation makes this look doable.

Just like an air-to-air IC, your system will move charge heat to the ambient air. Because heat never transfers without a temperature difference, you won't see ambient intake temps without ice. The intake charge must be hotter than the water, and the water must be hotter than the cooling air.

In rough numbers, the engine's cooling system needs to handle something around 200KW, while intake charge heat looks more like 20KW. The problem is that you want the IC's water to be close to ambient temperature, so it requires a bigger percentage of total cooling airflow than those numbers might make it appear.

If you build a system that gets enough cooling, the water temps will be reasonable, and there won't be an issue in extended driving. (Duh!) Heatsoak when stopped will be a problem, so a timer to keep the pump and fans running after shutdown could help. Your usage (street, strip, roadcourse...) matters here.

NissanConvert, you may be seeing the UIM & IAT sensor heatsoak, not necessarily the IC.

NissanConvert

iTrader: (1)

I had a thought regarding your idea. Eliminate the radiator, use an ice water reservoir and a pump to circulate cold water through the barel. (you can pick all of these up on ebay for about the price of a name brand air:air IC)

here's where my idea gets a little weird: get a dc beverage cooler (or some other waterproof cooler) and run the element through your ice water reservoir to maintain the low temperature. This runs on dc just like the pump so there's no stress mechanically on the engine. insulate the entire system (barrel, reservoir, lines) to protect them from your underhood temps and enjoy sustained sub ambient IAT's.

my thought is that the lower volume of the reservoir (about the size of a battery- where it would be located) and it's smaller surface area compared to a radiator would heatsoak less, weigh less, and be easier to mount. the idea is that the intake air is the only thing warming your cold water.

Saner

iTrader: (1)

BicuspiD, check out this thread. https://www.rx7club.com/showthread.p...=charge+cooler

Saner

iTrader: (1)

Also, check out these pix
http://www.zen44871.zen.co.uk/Pictures/W2AInstall/

Scrub

iTrader: (25)

I dunno if this was already posted, but PWR offers a air/water IC kit that includes a heat exchanger and pump. I believe the "radiator" is about the size of an oil cooler or a little bigger link and scroll to the bottom.

rynberg

No one I know has the slightest problem with intake air temps with a v-mount setup. I fail to see at all what you are trying to accomplish here.

Scrub

iTrader: (25)

agreed

Eggie

That's equivalent to cooling your PC by putting it in the fridge. TECs simply aren't powerful enough to handle the amount of heat in the charge air, so the water temp will increase whenever you boost. It won't fly except for brief & intermittent periods of boost.

Designing your car for the dragstrip? Use air-to-water with ice but no heat exchanger. This should work for autocross as well, but what class allows it?

Roadcourse? Air-to-air for an FD. (A2W makes sense only for difficult heat-exchanger placement, such as a mid-engined car.)

Street? Pretty much anything will work. As noted by OP, A2W is most complicated, least reliable and heaviest.

NissanConvert

iTrader: (1)

I don't know about you but on the street i only see brief and intermittent periods of boost. I've already weighed in on the general idea of a:w.

I've never used a fridge to cool my pc but i imagine it would work pretty well. in fact phase change cooling (which out performs liquid cooling) for pc applications is nothing more than the cooling element from a freezer designed so you can attach it to your cpu/gpu. but we need to cool air, not an object.

Eggie

Granted, but heatsoak could be a real issue here. Can't imagine having to wait 10 minutes for the temps to come back down after a 10-second pull. Anyway, the OP mentioned "track" use. If that means lapping days, a TEC won't work.

Fridges aren't designed for 100% duty cycle with heavy load. Mine had trouble staying cold when the switch failed, allowing the 30W light to stay on with the door closed. A modern PC's 100-200W would kill it.

NissanConvert

iTrader: (1)

heat soak would be a bitch. the system would have to be insulated reservoir, barrel and lines (although the surface area of the lines would likely be negligible)

The duty cycle wouldn't be 100% & you could set your threshold for cooling. Any temperature below ambient would be an improvement considering the increased efficiency of an a:w exchanger. my idea also included ice in the reservoir. I don't think that it would be too hard on a cooling element to maintain a gallon or so of water at sub ambient temperatures in an insulated environment.

however, i would have to check on the volume & temperature of the fresh from the turbos intake air.

Monsterbox

iTrader: (6)

www.swiftnets.com provides thermoelectric Peltiers for cpu's...they also carry some kind of waterblock sandwiched TEC Peliter that reverse cools the coolant system....you could use this somewhere on the coolant line

Bacon

iTrader: (12)

As great as an idea may seem, you overcomplicating a system for no reason, adding failure points, and just increasing in-efficiencies

The air to air v-mounts have been run with large success, coupled with vented hood and you have a near ideal setup.

Liquid to air IC’s are great for short runs, like drag racing, where you can put a liquid colder than the ambient air in the cooler section. With a system like your describing it will heat up shortly and stay that way for a while (a 3gal cell Filled with ice will be all water after a Ľ mile pass) Now imagine if you will that same heat being transferred into coolant, how long does it take for cooler air to blow off the rad fans when their running even with the engine off.

Now you have a system, that has to remove heat from the intake charge, transfer than into water, then take the heated water and have air pass back over that to try and cool it back down, why not just skip a step and get a efficient air to air core?

Air to water should be used for drag racing.

BicuspiD

Its more a cost issue than anything, since I have 80% of the parts needed for this. I am not trying to overcomplicate things on purpose - the prices for V-mount kits are exorbitant IMHO for a couple of brackets and an IC core (I have the radiator already) Plus I would need to make sure it worked with my vented hood specifically, which it appears most of the "kits" won't.

I thought with a full-size radiator it might act as an extra-large reservoir - plus with the extra surface area it would dissipate heat fast enough. Theres been a couple of production vehicles that have had A2W and it worked for them. Water has a great ability to absorb heat - the main question is would the volume of the system and the additional radiator shed heat fast enough to keep the A2W system around ambient at max load.

Saner - thanks - thats exactly like I was thinking for the most part - that core is a lot bigger than I envisioned though. Any other info or specs on that car?

rynberg

If you are fabricating everything anyway, why don't you just build a normal v-mount?

madbouncy

Worse comes to worse you could always run a line that has fins on it under your car and that'll let you carry more fluid plus the cool air under the car will cool any water in that line. Just make sure that it won't be hit if the car bottoms out.

Bacon

iTrader: (12)

Water is a great absorber of heat, agreed, but at the end of the day you’re still relying on air to remove the heat from your radiator core. I have never seen a radiator core that was more efficient in heat transfer then an ic but I may be wrong. Also you might want to investigate how the heat absorption of water drops when you add antifreeze (that is unless you winterize it, and don’t drive in the winter).. Might want to use Evans. It would be ideal since it pulls more heat out than water, and never freezes….

Eggie

Not according to Evans. Looks like Evans claims better engine-coolingperformance thanks to their higher boiling point, which had best not be a factor in an intercooler.

Kento

For the amount of time (and money) that you're going to spend fabricating and setting up a properly-functioning air/water IC (bracketry, plumbing, electric water pump, wiring, etc.), you could just as easily buy an air/air IC core and fab up some sort of homebrew V-mount that would offer the same benefits with a fraction of the weight and complication disadvantages that the air/water V-mount IC you're intending to build will have.

The basic reason that air/water ICs have been used on the vast majority of OEM applications is because of space/packaging concerns, i.e., there is not enough room to insert an air/air IC in the intake path between the compressor and the intake ports (for instance, the supercharged Mercedes models that use air/water).

CMonakar

Agreed.