[parmas]

Here is my opinion of PRE-Turbo Water injection after reading all posts:

1. Nozzle Position :

I am really surprised how in 9 years time, there is not a definitive answer on where to position the nozzle in a pre-turbo application. Some are saying directly to impeller will prevent blade damage but would result in abnormal airflow while others a few inches away or exactly on the filter will have the maximum time to atmoize and mix with Air.

What if we position the nozzle infront of the compressor wheel but instead injecting exactly the opposite way? Let's say we are activating at 10psi, the high intake flow coming from the filter will push the mist back into the compressor forming an umbrella type of mist. What do you think about it? Check attachment

2. Nozzle Size vs Head Flow:

Again after reading all posts, it seems that many of you are going insane flow levels and above recommended nozzle size. Some seen also wheel damage because of that. When we are talking pre-turbo, I agree with some of you that nozzle size should be between 10-50micron or 0.01-0.05mm. A 130cc/min nozzle is a 0.4mm while a 50micron is 16cc/min at the same pressure. The flow seems low compared to others flowing 200+ cc/min. True FOG is 30micron.

Quote : "If you are injecting pre-compressor at 2%-3% rate compared to air flow you will have about all the WI you need.

Suppose you spray at 2% air flow rate, and you have a 11.5:1 fuel air ratio at red line.

If you are flowing 65 lb/min, that is 29510 grams of air per min.
At 2% flow that means you would be injecting 590 grams / min of water.

If you have an 11.5:1 air fuel ratio than your fuel is 29510/11.5 = 2566 grams / min
Since most gasoline has a density of about .78 then that is 3289 cc/min
10% water to fuel would be 329 cc/min
15% water to fuel would be 493 cc/min

You would be spraying about 18% per min to fuel if you sprayed 2% of air by weight with a max power AFR of 11.5:1.

The beauty of using the air flow is is self corrects as you lean out the fuel.
the higher your AFR (say 12.5:1) the higher your percentage of water/fuel at a fixed water to air ratio.


3. Injection Pressure :

This is no taboo. The more the injection pressure is the finer the mist will be. A finer mist will cool the intake charge more in less time. Nowadays injection pressures above 150psi till 250psi are common.

4. Injection Activation :

Some are saying to inject at high levels of boost due to :

- Compressor wheel damage at low boost levels (under 9psi)
- Spooling is retarded due to colder EGTs

If nozzle is small (measured in microns) and pressure is high (150+psi), wheel damage should never occur.

Spooling should come earlier with pre-water injection due to thermodynamics pushing from adiabatic to isothermal having More Air per Less Turbo RPM equals to a better efficient compression.


5. PRE-Turbo vs Ambient Temps:

This was rarely mentioned but surely is something to understand that at lower ambient temperatures, Mist is more difficult to mix with Air in time.

6. Check Valve Importance

Through out the entire thread, this was an important factor to eliminate pooling. A check valve in the most vicinity of the nozzle with a high pressure rating works the best!

7. Injecting Hot/Boiling water

Hot water is easier to make it Mist while Boiling Water makes a lot of pressure on it's own. What if we can use the "FREE" heat energy from the exhaust manifold itself. This could be done by fixing a copper tube right on the exhaust runners and press the hot water into the check valve than to the nozzle.