Jeff

Here is some information:

Water injection systems are only needed in turbo and supercharged engines. The system has been around for a long time since it was already used in some World War II aircraft engines.

A water injection system works similarly to a fuel injection system only it injects water instead of fuel. Water injection is not to be confused with water spraying on the intercooler's surface, water spraying is much less efficient and far less sophisticated.
A turbocharger essentially compresses the air going into the engine in order to force more air than would be possible with the atmospheric pressure. More air into the engine means automatically more fuel has to be injected in order to maintain the appropriate stoechiometric value of the air/fuel ratio (around 14:1). More air and fuel into the engine leads to more power. However by compressing the inlet air the turbocharger also heats it. Higher air temperatures lead to thinner air and therefore an altered stoechiometric ratio which can lead to a lean mixture and detonation. In high pressure turbocharged engines the air/fuel mixture that enters the cylinders can explode prematurely (before the spark plug ignites, effect also known as engine knock) due to the extreme engine environment conditions. This situation results in severe engine damage in the long run (piston piercing). To avoid damage to the engine, water is injected, along with fuel, in the combustion chambers in order to provide a water/air/fuel mixture which not only burns more efficiently and avoids spontaneous detonation but also provides additional inlet air cooling and, hence, denser air. There are mainly three variations of water injection devices. They are dependent on the location of the water injectors. The first technique consists of injecting water at the entrance of the intake manifold. The second injects water at the exit pipe of the intercooler. The third technique injects water at the entry of the intercooler and is only used in competition vehicles. In this latter variation most of the in-cylinder detonation prevention is done by injecting additional fuel which is used as coolant (i.e. not burned).

How water injection works

The system, usually, is made up of 3 elements:

A water injector (similar to a fuel injector)

A high pressure pump (capable of at least 3 to 4 bar pressure and sometimes even more)

A pressure sensor connected to the inlet manifold

An inlet air temperature sensor

Usually a water injection system is engaged when the inlet air temperature is exceeding a certain value, typically 40 degrees Celsius, and the engine is on boost. The most advanced systems add to the above electronic circuitry that provides 3D cartography similar to what is used in fuel injection systems. Cartography based devices take into account many more parameters such air/fuel ratio, throttle position and so on.

Something to consider.

Jeff

[QUOTE]Originally posted by shaner
[B]On my endless quest to find/install an intercooler I have a question:

Which is better (more effective/efficient) ?

From an intallation point of view, compared to the custom-bent 3"aluminum piping that go all the way from the SC down to an intercooler and all the way to the TB, the Air-to-Water seems a lot more simple and much less custom:

All you have is the air-to-water exchange unit which fits easily and comfortably between the SC and the TB, an air exchanger/radiator which you mount easily in front of the radiator, a pump, and some simple rubber hosing to connect the radiator to the pump to the air/water unit...

So, logistically, it seems much easier to install the air-to-water.

shaner

Here's the link to the intercooled S2K... Aaron's SCed S2K:

http://www.foxmarketing.net./id22.htm

Supposedly this intercooler costs ~ $2000... a little much for a bit of bent aluminum piping and an off-the-shelf-intercooler.

I have a 12' piece of 3" aluminum piping... anyone want to help me bend it?

JDM S2000

How about something like this?

Stratocaster

Last post to this thread = Jul 8 2001, 07:46 PM
Your post to this thread = Aug 15 2006, 10:15 AM

Just a tad late don't you think?

JDM S2000

So I get flamed on if I dont use the search button and I get flammed on if I do?

Stratocaster

Not flaming, but I know for a fact that all of the poster above are long gone. So you question really has no context.

So "How about something like this?" mean what?

Slows2k

Moving to FI

trinydex

one thing to keep in mind about intercooler design is the latency of heat absorbtion. you need a certain amount of dwell time for the air inside of the heat exhchanger to actually exchange the heat.

in air to air units this translates into transfer tube length, you need a specific length to satisfy cooling to ambient (or whatever target temp) before the charge reaches the end of the tube. this "coefficient" we can call it can be modified with several factors; factors like efficiency of material, surface area, fin design etc. but in the end there's a critical length that must be used.

this does not change with air to water coolers. but you notice that air to water coolers are often shorter, smaller. it may be nice that they use a fluid of high thermal capacity and high specific heat but the fact is the water can only be cooled to ambient, and the water is not a miracle worker for transfering heat. it does transfer heat away from the transfer tubes faster than flowing air may, it does indeed increase surface area usage also. this would modify the critical length but i don't believe that the tight packaging that these units come with is many times sufficient to cool down to ambient temperatures. i may be wrong.

i've always thought of it as drag racers use air to water (to avoid heat soak) road racers use passive reliable air to air coolers. more steps in cooling system is more things to break.

fltsfshr

Has anyone tried a CO2 shot on the intercooler radiator and a cryo ball?


fltsfshr