more intercooler power

[GTRgeoff]

The primary need is to atomise the water as fine as possible, and I use the Spraying systems nozzle as identified in the autospeed article for both applications. I have the intake spray after the intercooler in the line where the air velocity is higher so there is less chance the water might settle out to pool. Before the IC it could settle out as the velocities reduce, much like an oil catch can or dry sump, although I doubt it with the heat. It is on a rising pipe as well so any overspraying or activation when the engine is not running will have the water run down to the intercooler. Just worried about hydrostatic lock. It is really a worthy upgrade.

[Warpspeed]

What water does is raise the detonation threshold.

To understand what this is, you need to understand detonation. What happens with detonation is that the trapped mixture is ignited by the spark and begins to burn in the area immediately around the plug. This burning causes the (mostly)nitrogen in the air to expand from the heat and increase the chamber pressure.

Now the burning continues until all the mixture is burned and pressure and temperature reach a maximum, usually at about 20 degrees ATDC. The ignition timing is early enough to always get the maximum at around 20 degrees ATDC.

What can happen though, is that the pressure and temperature in the chamber can get high enough to cause not burning but a spontaneous EXPLOSION. The whole lot detonates like a bomb creating a huge shock wave that breaks things.

So it is temperature and pressure that causes detonation. So you must lower the temperature and pressure reached DURING ACTUAL COMBUSTION(or use a less detonation prone fuel).

One way is to inject water. It does not have to be fully vaporised before it reaches the engine. Even a solid jet of water is going to flash into steam either during the compression stroke, or actual combustion. It is the high latent heat of water that lowers the peak combustion temperature and reduces detonation.

Another interesting feature is that the steam expands along with the nitrogen in the air to act as the working fluid that pushes down the piston. So although peak temperatures are much reduced, the pressures are not, and you lose no power by adding water, in fact you gain a bit.

A lot of people do not realise that it is the nitrogen in the air that does not burn which actually pushes the piston down. And steam works even better.

The reason I suggested fuel injectors is because they can meter in precise small quantities into every cylinder, and the fine spray is going to assist vaporisation.

Spraying water into the turbo inlet also works, but like fuel distribution, you have no way of knowing if that water is going to find its way into all cylinders in equal quantity. It will if it is fully vaporised, but it may not be.

[GTRgeoff]

Warpspeed

I like your explanation, saved me from digging through my archives although I would suggest that the nitrogen is not the only working fluid, even though it takes up some 70% of the atmosphere. This was the reason for oxygen injecting the Lynx 1.8 with stock exhaust and pod filter to achieve low 7 second 0-100 times. Also used an extra injector and water injection off a throttle switch to activate it all and activated it at over 3000rpm for a huge push from the little machine.

Anyway, have to go look for some new pistons. Time to go to that forged piston thread after the bearings went west and scored #3 big end journal and cracked 2 pistons prior to the water injection.

[Warpspeed]

Yes you are right. The other gasses and fuel do not just disappear, but the nitrogen working fluid is something that fascinated me when I first learned of it.

It is also why nitrous oxide works so well, it is mostly nitrogen (N2O). I believe pure oxygen will increase combustion temperatures and can lead you up the dreaded detonation path, so be careful.

[Merli]

One way is to inject water. It does not have to be fully vaporised before it reaches the engine. Even a solid jet of water is going to flash into steam either during the compression stroke, or actual combustion. It is the high latent heat of water that lowers the peak combustion temperature and reduces detonation.

Yes, everything you said is true, but I still stand by my claim that injecting the water further up the intake piping will give it more time to effect it's intake charge temperature drop, rather than an instantaneous conversion from liquid -> gas if you were to squirt it down the runners.

Also atomised water will absorb a lot more heat than a "solid jet of water", as it has a lot more surface area. Using fuel injectors will not achieve this at all.

[Warpspeed]

You are right, early complete vaporisation WILL remove heat from the intake charge, and lower induction temperatures. No argument there. Also lower charge temperatures mean more density, and this is extremely important for power production. So I agree.

But reducing detonation is a completely different thing to producing power. Detonation is only due to the peak temperature and pressure reached during actual combustion. Provided a certain mass of water is totally turned to vapor (boiled) the specific heat will reduce the final combustion temperature, and combustion will remain controlled.

So purely from detonation point of view it does not really matter where the water is introduced, or where along the chain of events it all finally boils off. During combustion it most certainly will all boil because the temperatures are so high.

[GTRgeoff]

Once again you are getting to the crux of the discussion. The cooler air is good, but the volume of water to cool the air is a tradeoff that sees no benefit from the cooler, denser charge. It is the detonation suppression that is the real benefit in introducing water to the cylinders.

[GTRman1992]

I agree with Warpspeed, I think the water would flash into steam due to the heat.

Hydrolic lock is the big fear, thats why you have a safety solonoid valve in the system that stops the engine drawing water down the tube when not in boost cycle. Also stops dribbling etc.

I'm going down the path of an individual fogging nozzle in each runner with a computer controlled pump (inputs: RPM, Boost, Water Pressure).

[Merli]

Okay... I see what you guys are saying now, and I agree.

[Edge]

what about a couple of extra fans for cooling the intercooler while waiting at the lights.

[GTRman1992]

Would probably also work, but not as efficient as water spray.