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Water does it again.


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As I have ranted previously, I'm a big fan of water injection.

Being slack, I haven't yet got round to fitting it to the wifes car although I did turn the fuelling up heaps.

This is a danger when you are running veg fuel as the excess can cause the rings to coke up and a loss of compression. That's the reason I originally fitted it to my vehicles.

Her car has been getting harder to start and I saw signs of the ring coking. In an attempt to make up for my slackness, I fitted up a WI system to try and reverse any effects of the veg overfueling.

Being a turbo I have done things a little different this time.

To trigger the water from a subaru washer bottle, I used a washing machine water level switch. These are far too sensative for the job requiring fractions of a pound to trigger but I wound it up as far as I could and it is workable if far from ideal.

I could put an airbleed in the line to up the actual boot pressure it triggers at but I intend to replace it with a proper adjustable hobbs switch.

I used my beloved micro mist garden watering nozzle and with a right angle adapter, I inserted the thing in the duct from the air cleaner facing straight down the air stream.

There is a lot of conjecture about putting the water before the Turbo and it causing erosion of the turbine wheels. I don't know if this is a real risk or more internet paranoia. In any case I think it would take some time to happen and I have other priorities with the engine short term.

I tapped a boost signal from the compensator on the IP to the washing machine level switch and that switches the pump. It still kicks in at anything above idle pretty much with the air con on so with one of the little garden irrigation taps in the line to the nozzle, I turned the water rate right down so the thing doesn't load up with water at low revs and on the over run. While the water rate is very low, it's also nearly constant to compensate.

One thing I noticed with this straight off as did my son when he drove the car is hw much better the thing revs out through the gears. I think that may be due to the effect of the water cooling the inlet air much better than the poorly designed in every aspect intercooler.

I have had the water on 4 days now and pumped about 16L of water through in very few KM. A lot of that was really drowning the thing when testing the flow rate and where the thing kicked in which was too early and too much. :P

People carry on about putting too much water in and hydrolocking the engine but it's amazing how much water you can pour in with no more than a stumble at worst. On one test run I did manage to drown the engine to the pint it stopped and took enough cranking to kill the battery to get the thing started again. No more damage than a lot of smoke, probably from washing oil and crap out of the intercooler.

Already the thing is starting MUCH easier and more reliably like it should. I think the water may have got rid of the worst of the deposits but I also think that properly cleaning the engine of any coking will take a while. I noticed with my Merc the effects were very slight but noticeable for months before the performance levelled out and given the physics of the problem I suspect with this one, I expect the process to be gradual as well.

One effect I have noticed is how much cooler the engine is running. The thing is nearly sitting on the thermostat all the time now except of course in traffic where the water isn't running. The gauge in this car is VERY sensitive. You can see the temp go up a fraction after just one squirt through a couple of gears on boost. That isn't happening now and the thing just sits on the low point of the margin when it is up to operating temp. I'm a bit surprised given how little water i'm feeding in.

Must be cooling the engine in the truck quite a bit given the amount I'm feeding that at full tilt.

I'm planning on fitting another injector to that right at the front of the duct where it comes into the engine bay to try and cool the inlet air and compensate for the engine heat. Given I think the water will all but have evaporated and what hasn't will hit the air filter element and go in as vapour only, I don't think I'll need to lower the amount of water I'm squirting right down the throat of the thing.

I plan when I get time to move the injection point to the discharge side of the inter cooler and use a 60 PSI pump I bought a while back for this job. I really want the water to enter the cylinders as drops not vapour as I believe this has a much greater cleaning effect. Again this is not what the purists and Internet experts recommend but they are also usually chasing power not cleaning.

So once again I have convinced myself of how effective WI is in cleaning engines. I didn't expect to see such a change in a few days. I was hoping to see some improvement in a week or 2 but maybe the initial saturation helped somewhat? I can see it but who knows? All I know is that we can go out and start the thing as it should now rather than have to crank it and hope the thing will fire before the battery gives out. It's still a bit temperamental when hot for some reason that defys logic ( and it's not an IP fault) but I'll give it some time and see if that improves as well.

I have learned my lesson from this, I won't run a diesel on veg without fitting WI. For vehicles with PCV problems etc, I think this would also be a preventative to any trouble with that as well.

When I have this set up right, I'll have all of about $50 invested in it. Best mod and insurance for the money I can think of for what I'm doing. :)

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I'm very curious about this, but I don't wanna experiment to the point of actually causing a damage to the engine as we all know ZD30 is rather fragile, in any case my goals are mainly the engine preservation and and fuel consumption reduction.

Have you noticed a fuel consumption going down or am I completely wrong here to even expect such result.

I also wonder if a mixture of methanol and water is the way to go for added power increase.


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I read an article on WI a while back and they said that WI when working perfectly should cause a very slight INCREASE in consumption. I forget the reasons given, but do remember thinking they were highly logical if against the hype. As I recall this was in reference to performance use in an SI engine.

In a diesel, there is reasonable citation of it causing a decrease in in consumption but I never look at consumption close enough to say.

What I would say is I think it is best not to expect a decrease in fuel consumption.

As for the Meth, the performance increase depends. When my 4.2 was at stock fueling, the meth gave it a real get up and go. Once I turned the fuel up, I had to run much less meth to stop the thing nailing. As such, the performance increase was much less because there was also probably less available unconsumed air to burn the extra fuel content.

I haven't tried the meth with the turbo car yet. A friend that has found the amount of meth he could run was minimal but then also discovered after an IP replacement that the pump had been wound up significantly as well.

Water/ meth will significantly lower intake temps however and the real performance increase could result from that.

I have also found a meth mixture to appear very superior in it's cleaning properties for reasons I can only guess.

I would suggest that you would be better off to turn up the fuelling on your vehicle for a performance increase simply because diesel is cheaper and easier to get than meth in most cases. That said, from the engine preservation angle, cooler intake temps and lower EGT's would be in the water/ meth mix's favour.

Also realise that you are asking about opposite things here. Not much use concerning yourself about economy when you are asking about performance. They are unfortunately two opposing outcomes. I have found on a couple of my cars that the water alone made a slight measured performance increase. Given it's going harder, I'd also expect it's burning more fuel.

There is conjecture to say differently, things like the water turning to steam in the cylinders increase BMEP however I think it's safer to assume more fuel will also be burnt.

As I have said before, the real significant factor is your right foot. I you use the power economy will go down.

If you use it sparingly, you may never notice the difference.

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