Water injection on 18psi supercharged 1600cc (Toyota 4AGZE)

[nick.parker]

Hi,
Just looking for some advice or reasons for the behaviour I have experienced. My Toyota 4AGZE engine is running a large supercharger giving 18psi boost pressure. Without doing anything else but turning on the water to a 0.4mm aquamist nozzle (from a 100psi water reservoir) the torque decreases quite noticibly (from the seat of the pants). The water sprays just after the throttle so goes through the supercharger, water to air intercooler then inlet manifold.
I noted that boost pressure increase 10kPa or so at the manifold with water injection active.

Has anyone experienced this loss of torque on their engine? What are reasons? Too much water?, too rich to start with, not enough advance?

Thanks, Nick

[awdrocks]

Yes I have to. I have a roots blower that works similar to yours. I spray before the throttle body, goes through the blower rotors, through the water intercooler then down my runners. I felt a big los in power. Im sure im spraying to much, I will decrease the psi on my pump.

What I dont understand is that I dont get a SINGLE degree of lower inlet temps.

[JohnA]

Interesting observations with these superchargers.

At what sort of boost level do you activate the WI?

[awdrocks]

Im at MAFv control. About 4,000 rpms..

[JohnA]

so what are the conditions that trigger the WI?
rpm signal on it's own isn't enough. What sort of load is on the engine?

[ae111sr]

I've got a Is system on my 4A-GZE and that is triggered at 6psi - about half of max boost.

[awdrocks]

so what are the conditions that trigger the WI?
rpm signal on it's own isn't enough. What sort of load is on the engine?

I have Snow Performance Stage II kit that with the MAF module trigger. I have it setup so it starts the pump when my MAF sees 3v and reaches peak at 5v.

Now the test I did was in a stationary nuetral position.

My inlet temp sensor is placed in the plenum by the back left corner next to one of the runners on the intake manifold.

[JohnA]

...Now the test I did was in a stationary nuetral position..
That's what I was thinking.
I'm not sure WI would be of any benefit in neutral --- there is no load on the engine, is there?

Maybe Richard or Hodrod can contribute here...

[awdrocks]

no load at all... I thought the same thing... but if im injecting pre-supercharger all the air that makes it to my plenum with my inlet temp sensor is already contaminated with the mist. If I was misting right into my plenum I could see how maybe only some runners get the mist, or maybe they all would but could possibly miss my sensor... but thats not the case... its misting in the air that THEN goes into my blower then through the intercooler THEN into my plenum and runners...

[JohnA]

I'm not sure how such early WI would work with a roots-type surercharger. Hopefully we'll get feedback from someone who has extensive experience with them.
It might even depend on the rotor clearances (that the water has to pass through)

[awdrocks]

I'm not sure how such early WI would work with a roots-type surercharger. Hopefully we'll get feedback from someone who has extensive experience with them.
It might even depend on the rotor clearances (that the water has to pass through)

Well according to Snow a roots style blower is the best candidate for WI. I know the WI in making it to the cumbustion chamber because I can feel the motor quench. Im not going to bother messing with pump strength etc yet untill I get my 49/51 water/meth mix. Then ill start all the tuning.

But I should be seeing SOME inlet temp drops right now.. :sad:

[JohnA]

..But I should be seeing SOME inlet temp drops right now.. :sad:
not necessarily.
Where is your temp sensor placed?
I see from an earlier post that you have a water/air chargecooler. Is the sensor after the chargecooler?
Being a heat exchanger, that would work best with large temp differences between the cooling medium and the air going into it.
If you are cooling the air before the chargecooler, then you are effectively reducing it's efficiency. So what temp reduction you gain from the W.I. you may be losing from the chargecooler working less efficiently.

One hand giveth, the other taketh away :wink:

[awdrocks]

..But I should be seeing SOME inlet temp drops right now.. :sad:
not necessarily.
Where is your temp sensor placed?
I see from an earlier post that you have a water/air chargecooler. Is the sensor after the chargecooler?
Being a heat exchanger, that would work best with large temp differences between the cooling medium and the air going into it.
If you are cooling the air before the chargecooler, then you are effectively reducing it's efficiency. So what temp reduction you gain from the W.I. you may be losing from the chargecooler working less efficiently.

One hand giveth, the other taketh away :wink:

My inlet temp sensor is after everything and betrween two runners on my intake/plenum. So my sensor is reading the final air thats actually entering the cylinders.

Check it out. The sensor is on the top left.

What if I sprayed right obove intercooler after everything. Im just scared of hydro-locking and maybe not all my runners will get the same amount or juice.


http://members.tccoa.com/awdrocks/sc5-500.jpg

[markbudgen]

Hello,

I thought that it was considered better to have WI after chargecooler/intercooler. At least that is what the attached program suggests so that system efficiency was maximised.

BR, Mark.

http://not2fast.wryday.com/turbo/glossary/turbo_calc.shtml

[JohnA]

Yes, Mark is saying the same thing.
Since you read the inlet temp just before the engine (as is best) then you read the final effect after all intercooling attempts.
Spraying before the chargecooler simply reduces it's efficiency, because it has less temp differential to play with. The upside is that because it works less, it will not heatsoak as quickly as it might do if it were alone.

Spraying before the chargecooler is sometimes desirable, say when the chargecooler is undersized for the amount of boost/airflow it is meant to handle. There are no hard-and-fast rules, it all depends on the particular setup. :smile: