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Whislt it can use tube & fin, bar & plate, or shell and tube.

I think a water/air intercooler would work really well on an RB20 or RB25.

Grab a thrown away STI intercooler (would assume reasonable pressure drop) and weld up some plates with fittings, grab a pump, radiator, maybe even an ice box for the boot, and you would be able to mount above the turbo/rocker cover for a very short inlet tract. Very stable inlet temps, (ice box for those times when you want that little bit more) and crisper throttle response, plus water to air intercoolers are technically more effecient then air to air... though there is the issue of weight, complexity of pumps etc etc.

Still im surprised more ppl who are sticking with something like the std turbo, or 2530 on an RB20 dont do it. Piping route is simpler, no chopping of front bars, and the possibility of inlet temps below ambient, something that is not possible with air/air coolers...

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and the possibility of inlet temps below ambient, something that is not possible with air/air coolers...

How would you get an inlet temp of below ambient? The cooling water would be at ambient, therefore the inlet temp could never be less than ambient. (Would never even reach ambient, will always have to be at least a litttle above.)

Unless ur talking about putting ice in it, which is only a very very short term solution?

Or am i wrong?

Bar and plate and tube and fin are the most common types, they're really pretty similar.

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Dont get too caught up in the hype of intercoolers unless you are going for ultimate performance. The reality is that they dont really give you much in the way of extra power (except by removing pressure drops) but they make the car much more reliable by avoiding the heat sink effects of the std intercooler.

IMHO a Aust. made front mount is just as good as an expensive import and you will not see any real difference between the two. Just look for a good priced 600x300 ish intercooler (new or second hand) unless you are building a car where every little bit counts.

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After you have been driving, your right, air is ultimately cooling the water thru a front mounted heat exchanger, but if you throw an ice box in the boot, say a 5L circular bucket with copper tube wound up inside it, and fill with ice, you will find that you will be able to maintain nice chilly inlet temps for a few 1/4 mile runs, even dry ice.

But thats agor, more weight, and more complexity... however i still think a nice water/air intercooler is just the thing for a street driven RB20/RB25 with a low mount turbo. Constant inlet temps (in traffic the water/air cooler is better, as the air/air only has a limited heat sink effect and needs airflow accross it to work optimally) and an inlet tract that is measured in inches, not feet.

Assuming the volume of the intercooler is about 1/2 (more like 1/3) of what your typical front moutn is, then you only have 9 inches of tubing, talk about crisp throttle repsonse.

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The reason you have "Constant inlet temps (in traffic the water/air cooler is better, as the air/air only has a limited heat sink effect and needs airflow accross it to work optimally)"

is becuase the water is taking the heat energy into its intermolecular bonds, so your right with no or little air flow the aire/water cooler is more stable becuase of the high specific heat of water.. the let down of this is of course that its very hard to cool the water down again when you get going, at least with air/air once you going it rapidly disappates the heat aquired while "sitting at the lights" so to speak.

As far as i knew water/air was a bit of a drag car set up thing, where they dump the water and put in nice new cool stuff at the end of a 1/4mi. Imagine changing the water in the system at every set of lights! :P

Also while the cooler itself doesnt give you extra power in the true sense of the word, if you increase your boost pressure to compensate for the pressure drop across the cooler, then you will infact have.... more power. And if you are like me and are limited by detonation before anything else, a cooler will solve alot of problems.

Brent (A non-fan of air/water coolers :( )

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xRHETTx remember back to when you where a kid and you jumped out of the pool when a breeze was blowing. You felt really cold didnt you. Its called evaporative cooling. Theoretically with enough windspeed over a wet surface the water molecules will evaporate ie change state from liquid to vapour and in doing so absorb energy in the form of heat (from the surface it is in contact with) cooling the surface below ambient.

That is the theory but in reality you dont have a snow flakes chance in hell of bringing the intake temp below ambient without something like an air con system cooling the intake and even then getting enough heat transfer would be a problem. This system would suffer from the same problem as the water to air intercooler, that being you still have to pump the cooling media around the system adding weight to your car and using energy (robbing power) to do it.

I believe that you can do several things to reduce you inlet temperature

1) Pick a turbo which is efficient at your chosen boost / air through put.

2) Make sure your ram pod is drawing air from a cool location (not from under the bloody bonnet).

3) Put some vents near the firewall in your bonnet facing the firewall. This will remove heat from the engine bay and stop heat soak (massive problem of mine up here in the NT)

4) HPC coat (i know that is a tautology if anyone is being picky) your intercooler piping to stop them from heat soaking, it is debatable if this has any effect but some people swear by coating the pipes (bonnet vents are more useful in my opinion).

5) Ask ARE what they think is the best intercooler for you application and go with it.

6) This step goes back to the evaporative cooling above. Simply put a water spray system with a VERY fine nozzle (check autospeed i remember an article about doing) after the intercooler and before the inlet manifold. This will basically spray very fine water into the air rushing past and in doing so due to the finely misted water being sprayed into a hot air stream it will evaporate and when the change of state occurs it will draw heat from the air dropping your intake temperature. CAN ANYONE TELL ME IF THE INCREASE IN HUMIDITY LEVEL HAS A NEGATIVE EFFECT ON THE ENGINE/TUNING/ETC?

7) This one i read about on autospeed as well. Some company several years ago made a spacer plate from some insulation which goes between you inlet plenum and the head. This will theoretically reduce the temperature of the last point of contact for you air charge before entering the engine. Again it is debatable if it makes 3/5ths of fck all difference.

8) Last of course is the intercooler water spray relying on evaporative cooling the intercooler but in this case your car would have to be psychic to know when to start spraying. I liked an article in autospeed where julian edgar started the intercooler spray dependant on the rate if change of the voltage from the throttle position sensor. ie if you are racing you are obviously ramming the throttle to the floor as fast as possible to accelerate fast and the rate of change with respect to time of the accelerator is high hence it would start the spray so your intercooler is sprayed ready for you next gear change.

NOTE I DID NOT READ EACH POSTING IN THIS THREAD SO NO ONE GET UPSET IF I HAVE REHASHED THEIR IDEA

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FYI guys i live in the NT, i am running a stock turbo at 13psi and half my driving life revolves around watching my pfc hand controller to make sure that it is not pinging. Also heat soak is a major problem, in the evening when i head home i wait until the engine temp is up before i allow positive inlet pressure. If i park the car after that drive for say 10 to 20mins then take it for another drive it will lightly ping the whole time because the engine has heat soaked.

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