1. Frontal area.
2. Pressure drop across the cores (external and internal).
3. Road speed.
4. Air temperature differentials (external and internal).
   To simplify the calculations, given that there are so many variations in size and efficiency. We start with an intercooler with 50% efficiency. We will calculate how much heat is being removed for a given mass airflow based on a boost pressure ratio of 2 at 6000 rpm, using the same 2-litre engine. The result will be used to compare against a water injection system. Ambient air temperature is 25°C and the compressor exit temperature is 124°C. At 50% intercooler efficiency (reasonable assumption as both the engine and intercooler is operating close to their peak flow limits), the temperature drop across the inter-cooler should be:
   (124°C - 25°C)/2 = 49.5°C. The final air temperature entering the engine is 74.5°C.

35. We shall see the intercooling properties of water injection.
    Water temperature is 25°C and the compressor exit temperature is 124°C and Water flow rate of 250cc per minute. In the region we are working in the partial pressure of water vapour in the mixture is very low. We can assume that the enthalpy is a function of temperature alone within reasonable accuracy (e.g. for 250g /min of water and 8.64Kg/min of air, the partial pressure of water in about 0.06 bar). Consequently the final temperature is an inverse linear function of water proportional as nearest makes no difference. The calculation and results:
    At 200cc/min: 66.09°C
    At 250cc/min: 50.88°C
    At 300cc/min: 36.27°C
    So there we are, we have proved our point, water is just as effective as an intercooler. We decided to calculate a few more water flow rates so that a chart can be plotted, useful for visual prediction. Even at a modest flow rate of 200cc per minute, water is a better cooler than a 50% efficient intercooler by a long way. Notice at 350cc/minute of water, the final temperature dropped below the ambient of 25°C !!! there just isn't a 110% efficiency intercooler around yet ...

all of this was found at http://www.turbodynamics.co.uk/water.htm

Of course you wouldn't need it for the street, but I found a guy that uses it on a bike that he races at the Bonneville salt flats. The motor runs 11:1 compression and then he's boosting at 22psi. There is no way he could fit a big enough IC to keep it from detonating, so along with an IC he made a custom water injection kit.

No jake the Civ isn't getting a turbo. I can't afford it after I bought the Monster.

I was going to ask you if we could use it on the next car. Does it say in the rules that we can't use water injection?

I agree that a properly set-up street configuration should not require water injection, but it surely couldn't hurt at the track. It could also be cheap engine insurance. The high-dollar controllers monitor things like boost, IAT, det, TPS, EGT etc. so they react quickly to your driving conditions.

If you have a large enough intercooler, it will act as a heat sink to help prevent temporary intake temperature spikes, but the water injection squirt will always be a little late getting to the engine.

I used to work with a guy who used this kit http://www.aquamist.co.uk/ on his Lotus Esprit 2.2 turbo, and he had really good luck with it.

This is a really inexpensive DIY kit:
http://www.autospeed.com/cms/A_0527/article.html
There are 6 parts to this article, you have to search for them and open them separately. Prices are here:
http://www.autospeed.com/shop/category_705/browse.html?

The autospeed kit looks like a pretty good deal. Are you looking at turbo-ing the Civic, Schwanger? It's too bad they don't allow water injection in FSAE. I'd be all over that.

my head hurts just thinking about it..

Water would make the intake charge denser. The liquid water "absorbs" some of the heat from the intake air, so the liquid then turns to steam. So the cooler intake air would then be more dense.

I don't think it's as big a headache as you think 92BlackTT, there are 2 adjustments on the less expensive kits, water metering (jet size) and timing (Pressure switch). The pressure switch can be set anywhere from 3-30 psi and comes preset at 10 psi.

I just wanted to bring it up, I'm not saying it's the solve all solution. I'm playing the devils advocate.

AcesHigh wrote:
Water-to-air intercooling and Water Injection is different.

beats head against desk

(I give up)

Nitrous does exactly the same thing as you described above, except with its evaporation it also releases oxygen. Not only does it cool your air charge, it would make oxygen more readily available. Water would not make the intake charge denser.

Schwanger wrote:
It's realy not the same. You have to run a pressure sensor in your intake (MAP) so it it only injects after a certain pressure. The water is then absorbs some of the heat for the intake air and is passed through the engine where it leaves as steam through the exhaust.

From what I've read it is completely worth it if you want to run a lot of boost. You can run much higher boost without having to retard the timing or dump a shit load of useless fuel in just to keep it from predetonating.

http://www.3sxperformance.com/alcoholinj.asp

id order a bottle or two of advil while your at it

I think your better off spending your money somewhere else in my opinion...

From what I've read it is completely worth it if you want to run a lot of boost. You can run much higher boost without having to retard the timing or dump a shit load of useless fuel in just to keep it from predetonating.

Schwanger wrote:
I'm not talking about spraying it onto the intercooler, I'm saying that you spray it into the intake. Many WRC teams use it.

in the upper intake

Same thing, his is just spraying over his IC on it's way through his intake

Never got a chance to run it...ran into issues with his new heads and ended up tearing the motor down again (and in turn decided to go farther and pick up a new block)....car should be running next spring.

The way it sounded....if you knew what you were doing and had hours of dyno time available, it was going to be a real good thing.