Water injection for my 300Tdi

[JimAttrill]

When I was in the RAF in Germany, 1970-3, we used to use Bols Vodka in the screenwasher bottles as being duty-free it was cheaper than screenwashing liquid. Worked well, and if all else failed you could drink it, being ethanol after all

I apologise for the delay in getting on with the water injection, but I have to wait on the US post and the local customs.

[JimAttrill]

Sorry about 'bumping' this thread, but I have a bit more info (although the bits haven't arrived from the states yet):

Water Injection Calculations:

According to the seller, the nozzle will pass 2 US gallons/hour at > 40psi.

1. 2 gallons US per hour = 7.57 litres per hour

2. which is 7570 cc per hour

3. which is 126.16 cc per minute

4. which is 2.1 cc per second

1. At 100 kph, the engine will use 10.5 litres of diesel per hour

2. which is 10500 cc per hour

3. which is 175 cc per minute

4. which is 2.92 cc per second

So, total volume per second rises from 2.92 to 5.02 per second.

A rise of 71.9%

Any views anybody? (Apart from the fact I will need a much bigger water tank than the washer bottle)

[JimAttrill]

The boost switch and the nozzle have arrived from the states, and the customs only charged me a bit of vat on them! I have been mucking about with a Disco ex-EGR pipe to mount the atomiser and the switch.

I also did a test of the atomiser using the Disco headlamp washer pump. It is as I thought, about 2cc per second, which may be a bit too much. I have my doubts about how long the pump will last - I may have to use the TD5 fuel pump instead. And I have a spare headlamp washer pump as well.

I will finish the installation this weekend and post some photos.

[Lara]

Have a read of this!

http://homepages.cae.wisc.edu/~rutland/res...000-01-2938.pdf

On a less techy front,

Be conservative with the amount of water you inject but you will notice a performance increase if you are running on or near the "smoke limit" of a diesel engine,

You will gain nothing if injecting 100% water and running lean as most standard diesels are setup from the factory, usually about 20% lean so you need more fuel not Oxygen,

If you do a 50/50 Methanol mix then you will see a power improvement in both scenarios, due to the much higher latent heat of vapourisation on the Methanol lowering the intake temperature significantly more, and the added fuel value of the Methanol its self.

Complete Kits are available from Summit Racing in the states for about 200 GB.

Good luck,

Lara.

[JimAttrill]

The techy bit is interesting, but as I cannot implement Direct Water Injection it is somewhat irrelevant to my system, which consists of what they call 'fumigation'.

200 GB pounds is not in my budget at all, either. Thanks for your other comments.

[Guest otchie1]

My worry would be that as the water pump needs to be robust enough for a heavy duty cycle and good enough to reliably pump your 2cc/sec@40psi, you may well end up losing any power gains in pumping losses thereby just getting more power at the expense of more fuel.

Fascinating though - was water injection used in aircraft because of the need to compensate for lower ambient pressures at altitude or was it used on take off because the engines were designed to operate at altitude and were therefore inefficient at sea level?

Are you hoping to cool the air by getting it to evaporate the vaporised water or are you hoping to 'bulk out' the air charge by adding vaporised water and hence upping the post-compression, pre-ignition chamber pressure? - I could always just export some local fog to you if you want proper LR air to play with

How is it likely to stack up against just skimming the head or wacking a bigger intercooler on?

Now i want a 200Tdi to modify.

[JimAttrill]

My worry would be that as the water pump needs to be robust enough for a heavy duty cycle and good enough to reliably pump your 2cc/sec@40psi, you may well end up losing any power gains in pumping losses thereby just getting more power at the expense of more fuel.

Fascinating though - was water injection used in aircraft because of the need to compensate for lower ambient pressures at altitude or was it used on take off because the engines were designed to operate at altitude and were therefore inefficient at sea level?

Are you hoping to cool the air by getting it to evaporate the vaporised water or are you hoping to 'bulk out' the air charge by adding vaporised water and hence upping the post-compression, pre-ignition chamber pressure? - I could always just export some local fog to you if you want proper LR air to play with

How is it likely to stack up against just skimming the head or wacking a bigger intercooler on?

Now i want a 200Tdi to modify.

To answer your questions in order - I don't expect the Disco headlight washer pump to last, it is made by Valeo after all

But I do have two of them, and if they both fail I have a dissected TD5 fuel pump high pressure stage only which seems to be heavier/more robust. As I said in the title, I am doing this on the cheap if possible.

Water injection was first used in aircraft that often had two-speed two-stage superchargers with intercoolers between the stages. Water injection allowed the max boost pressure to be increased because it stops detonation - normally more fuel is injected along with the water to give more power. For takeoff only, not used at altitude at all. The Griffon with WI could go up to 24psi boost, a lot even today, whereas without water it would be about half that maximum.

Yes I am hoping to increase the density of the incoming charge by evaporating the water. It does often get hot here (though not at the moment) and I do have an EGT gauge so I can see what is happening. My prime purpose is to lower the max EGT to safe levels and hopefully decrease fuel consumption. I am not really after more power.

Skimming the head is death to diesels as the cr is already very high.

I can't afford a fancy intercooler

[Guest otchie1]

Ta for that Jim.

I've had a read of that technical pdf from Daimler a few posts up.

Although they are specifically looking at direct water injection in which the fuel and water are mixed in the injector just before injection, they do mention your 'upstream' method as well which they call fumigation.

With fumigation they note that the water ends up in the 'wrong' part of the combustion bang to have the best effects. They also worry that water could contaminate the bores and sump oil which would be bad.

Adding water delayed the ignition event in their calculations and experiments.

The benefits also vary according to engine load; 44% load had better(lower) soot & NOx figures as well as better fuel efficiency; 86% load runs had worse soot & fuel efficiency but better NOx.

Their overall conclusion was that it would take much tightened NOx emission regulations combined with long term high fuel prices to make the technology worth pursuing for DI diesel engines.

Respect and credit to the authors - Bedford, Rutland, Dittrich, Raab & Wirbeleit.

[Henk Coetzee]

I've had a read of that technical pdf from Daimler a few posts up.

Although they are specifically looking at direct water injection in which the fuel and water are mixed in the injector just before injection, they do mention your 'upstream' method as well which they call fumigation.

This is an interesting idea for a diesel. As an alternative, I bought some diesel like this in Lesotho a while ago. They do an excellent diesel-water premix. I can't say I felt any difference in performance, although I hid behind a smoke screen on all the descents .

[JimAttrill]

Well, I am nearly there, just got to put the wiring inside the cab; switch and light etc. Here are some pics:

In the foreground is the spray nozzle, at the rear is the adjustable boost switch.

Here is the whole setup including the Disco headlamp washer pump and the relay. On the manifold is the EGT probe.

The little grey thing in the water line is a VDO non-return valve.

[Guest otchie1]

Good to see it progressing.

Keep an eye out for water in the sump.

[Guest otchie1]

This is an interesting idea for a diesel. As an alternative, I bought some diesel like this in Lesotho a while ago. They do an excellent diesel-water premix. I can't say I felt any difference in performance, although I hid behind a smoke screen on all the descents .

:lol: I'll give Lesotho diesel a miss then.

Hopefully your fuel filter sorted that out for you but Jim is squirting it right in to the manifold. Scary

[JimAttrill]

What scares me is the possibility of hydraulicing the engine, so I will start off with only injecting the water at .9 bar or so, and gradually reduce it. The guys in the states reckon I can inject at .2 bar and above, though that seems a bit low to me.

If you hydraulic the motor, this is what you get - this happened on the starter motor with a blown head gasket.

Not my engine, I must add!

[GBMUD]

You would have to put in a hell of a lot of water to hydraulic a running engine. Just make sure that water cannot syphon in when the engine is not running, IMHO that presents the greatest danger. I guess that there is no danger of water accumulating in the manifold and then going in all at once?

Chris

[JimAttrill]

That is partly the reason for the non-return valve as it does take some pressure to open. So water cannot syphon in. Also the boost sensor will only switch on the pump at a preset value. The sensor has NO and NC (normally open and normally closed) connections and I am using the NC to switch the pump on above the set value and switch it off when the pressure drops.

I do have an alternative to use my EGT aircon controller switch setting to switch the pump on and off above a certain EGT: at the moment that switches on an alarm buzzer and a flashing red LED. Possibly the ideal would be an interlock between boost and EGT where the pump would only switch on if, say, the EGT were above 500c and the boost above .7 bar. Or whatever figures one wants to set, the hardware is there already!

I will have an override switch in the cab because I don't think I want to inject the water into a cold engine. If this all works I will fit a float switch to the tank so that the pump will not work if the water level is too low. I already have a float switch in the expansion tank for a low coolant alarm, so one of the same floats will do, but upside down with an NO relay. And if it works I will need an extension water tank because the windscreen washer tank will not really be big enough.

What I can't do is vary the flow depending on any parameter. The pump either pumps or it doesn't. The fancy systems they fit to WRC Subaru's and others is to connect the whole shebang to the engine ECU and pulse the sprayers depending on the throttle opening, revs, boost, etc.

So in the ideal state, I would have the WI switch on only if:

1) the engine is warmed up, though we can really ignore this because of 2)

2) the EGT is above a certain figure

3) the boost is above a certain figure

4) there is water in the tank

Watch this space!

[Guest otchie1]

What I can't do is vary the flow depending on any parameter. The pump either pumps or it doesn't. The fancy systems they fit to WRC Subaru's and others is to connect the whole shebang to the engine ECU and pulse the sprayers depending on the throttle opening, revs, etc.

Throttle the pump supply voltage with a variable resistor maybe? Nice old fashioned rheostat will be up to the job so long as it's bolted to lots of metal.

[JimAttrill]

At this moment in time (as politicians say) I am not even sure that the pump will work against the boost pressure. After all, it is just an old Disco headlight washer pump. If it doesn't work I have a high-pressure stage of a TD5 fuel pump. I did say I was doing this on the cheap The US suppliers wanted $110 for a good pump, I have no doubt they are right, but I don't have that sort of money, and as I am looking to save money by improving fuel consumption rather than having more power, I have already spent enough at $55 US. It is also fun.

And if my engine goes bang it won't matter too much as it already has 270k kms on it and is due for an overhaul. I have all the bits, sleeves, pistons, etc in my garage waiting for the day of the overhaul. But the engine does have sentimental value to me as it has never let me down in 12 years, and I will be the person who does the overhaul with loving care.

[MarkieB]

look at this site: http://autospeed.com/cms/A_110368/article.html

There are quite a few articles there; very fascinating

I had been thinking of this since a news item in France recently: http://www.ecopra.com/home/index456.html for those who understand

It looks as though they've put their prices up since the news item..

One more lot - in the UK - quite pricey too, are http://www.aquamist.co.uk/sl/plist/frm-4.html

one of the autospeed articles seemed to think that spraying water on the intercooler was the most efficient, least risky answer - with a sufficiently economical kit, I suppose that would be similar to investing in a very large intercooler? John, would you think you could possibly make improvements such as better atomisation, more water, water better directed at the intercooler, that could feasibly lead to better results?

cheers

[Guest otchie1]

one of the autospeed articles seemed to think that spraying water on the intercooler was the most efficient, least risky answer - with a sufficiently economical kit, I suppose that would be similar to investing in a very large intercooler?

cheers

Works on the same principle as sweating on a hot day and has the same draw backs in that it requires lots of fluid to work and leaves wet patches all over the place. Probably great for a short burst of high performance if you can guarantee a source of cold/iced water but not a lot of good if your aiming for better fuel economy.

I rather fancy that simply sticking a fan on the intercooler ala mitsubishi will generate a similar effect with less bother.

[Disco_Jonty]

Hi Jim,

I came across this post looking for some information on WMI.

I found it very interesting what you've done, but I don't see a conclusion?

Did it work, and was it worth it?

I have a 300tdi and I am looking into installing a WMI system, but I am not looking for oodles of power, I just want lower EGTs and maybe a little more power on those long uphills on hot afternoons. Did you try a water meth mixture or just water?

I don't want to play with timing or boost, as the plan is to only use the WMI when I need it.

Any response would be appreciated

[Troll Hunter]

Hi, Disco_Jonty,

My 1991 110 CSW has a 300Tdi engine with an Allisport standard sized intercooler, tweaked FIP and a VDO EGT gauge. I installed a WI kit supplied by Devils Own Water Injection. Feeling flush, I bought their injection pump - 150psi discharge pressure, I think - and did a bench calibration using their 5gph injection nozzle. This proved to be very accurate, and produced, at ambient pressure an incredibly fine mist. I have no reason to think that an increased back pressure of 1 bar would significantly degrade the nozzle performance. I mounted the injection nozzle in the rubber hose between the intercooler and the manifold, and the actuating pressure switch in the same line, but upstream of the injection point. I mounted the pump under the front passenger seat - my vehicle is LHD - and installed a 5 gallon water tank behind the second row of seats. I set the pressure switch to start injection at 4psi of boost.

I was looking for a reduction in EGT temperatures and smoke emissions under hard acceleration or a long hill climb, and we have plenty of these! I was not particularly looking for increased power, so I used water only, not a water/methanol mix.

My results: virtually negligible reduction in EGT or smoke emission under heavy acceleration; but, an improvement of 5-10% in fuel economy. And in Canada, where nowhere is close to anywhere, and your turbo is producing significant boost pressure most of the time, replenishing water supplies every hour is a PITA. At 4 -5 GPH the water consumption is significantly more than the fuel consumption. Consequently, I've stripped the kit out, cut back the FIP tweak, which has fixed both the high EGT and the excessive smoke, and solved the problem of frequent water replenishment. Also, I probably get a slightly improved fuel consumption since I'm not blowing out anywhere near so much incompletely burnt fuel (smoke). I should add that I never switched the WI on until the engine was warmed up and the EGT was up to 300Deg C/575Deg F, and I never saw any sign of water in the engine oil, and I checked for this regularly.

My conclusions: For the traffic light GP against go faster striped boy racers, water/alcohol might give a boost, but forget WI for day to day driving, especially for any long journeys, and without a water/alcohol mix, ie winter screen wash, forget using it in winter.

Mike