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Water injection for my 300Tdi


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Anybody ever tried water injection? I am about to fit it to my 300tdi. I got the spray nozzle and an adjustable boost switch from Devilsown in the US, haven't arrived yet in the post. Have an extra Defender windscreen washer bottle, VDO non-return valve and a semi-defunct and dismantled TD5 fuel pump waiting to be fitted. And the normal wires and relays etc.

I don't suppose the TD5 pump will like pumping water much, but it is scrap anyway as the LP side don't work. The Sureflo pump costs $110 so I looked around for a cheap option.

I'll keep you posted as to how this works: I am mainly looking to increase volumetric efficiency and thus decrease fuel consumption rather than have more power. I have an EGT meter so will be able to see what effect the water has. Will possibly mix a bit of methanol in with it.

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If you're looking ofr a good quality high pressure and high flor water pump I can recommend the headlamp washer pump from an RRC or a disco. They have the added bonus of coming ready attached to a suitable washer bottle to boot. The headlamp washer pump with the hose disconnected can empty the tamk in about ten seconds with a hell of a lot of pressure.

NOS actually isnt such a stupid idea Nige, but the issue comes in providing the extra fuelling, as its really hard with a mechanical injector pump to shove the extra fuel thats required in at the right timing! I cant see why it wouldnt be possible with a TD5 say or something with electronic injection.

Jon

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Jon, I have been looking for a headlamp washer pump from a Disco, and will possibly go that way if I can steal one from a client's car without him noticing!

Hang on, looked under the benches and found a Disco I tank with three pumps in it, two small windscreen washer pumps and one larger one for the headlights. So I have snaffled that for my project :) The pump comes out quite easily, I don't have room to fit the large water tank in the Defender but can plumb it into the existing washer tank which is quite big.

And I still have the TD5 pump so can check to see which gives the greatest pressure.

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Jim, I'd say go for it - I don't know anyone who's done it but I see know reason why it shouldn't work. I've been told it can be a bit of a pig to setup but the chap who told me that tends to like finding problems rather than solutions. What's always held me back is the fact you have to carry water and once its out you've got problems. To get the new truck up and running I'm going to start off with a conventional air/air intercooler however I will then start playing with charge coolers as there's some really funky stuff you can do. Its not cheap but there is the potential to get more than 100% cooling (ie inlet temperatures lower than ambient!) :o

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I am getting a boost switch which is easily adjustable (under the bonnet, nothing fancy) to what boost pressure it will switch the pump on. They recommend .2 bar but that seems a bit low to me. I am also tempted to add a full throttle interlock, but don't know about that. The aircraft engines with water injection I worked on had that, but they also used to increase the fuelling to take advantage of the increased volumetric efficiency of the engine. I worked on three water injected engines, of different types, ie.

Rolls-Royce Griffon V12 supercharged to 27psi for takeoff in Avro Shackletons

Rolls-Royce Dart turboprops on AW Argosys

Rolls-Royce/Bristol Pegasus in Mk 1 and 1A Harriers.

In the last we didn't use the water injection because the engines only lasted a few minutes before the electonic system told us to change it. It would use 50gal of water/methanol in 60seconds!

I reckon charge coolers are a great idea, just a bit expensive what with the water pump and extra radiator. As I have aircon I don't know where I could actually fit the radiator. If you really want to move you can put ice cubes in the rad!

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from what i can understand fitting water injection to a derv wont do what you want it to,

on a petrol engined vehicle its used to slow the burn as such & lower the chance of DET, however on a diesel engine that uses compression ignition if you slow the burn it in theory should give a loss of power & a bit o wasted fuel going out the exhaust as it didnt get burnt fast enough

Mike

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But you must remember this is a CI engine with a turbocharger which increases the inlet temperature by at least 60c. So decreasing the inlet temp by any means can increase the volumetric efficiency of the engine.

Anyway we shall see .... :)

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Sorry, but you clarify what you mean by 'injection' ?

Are you proposing to atomise water into the engine intake and combustion cycle or sprayed over the intercooler to improve intercooler temperature drops ?

The first. The most important bit is the atomiser, which is on its way to me from the US. Spraying the intercooler is easy because you can use garden watering spray nozzles. I reckon on the 300tdi it would be handy to spray the whole inlet manifold as it gets heat soaked from the turbo underneath. But that comes later.

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We used to fit water injection kits to Saab turbo engines back in the early 80s, very effective they were too in conjunction with some boost and fueling mods. Never thought about it on a diesel though.

Anyway the kit consisted of a fairly basic nozzle, pressure switch, relay and a windscreen washer pump. The unit was triggered when a certain boost pressure was reached.

I would have thought that how sophisticated the atomiser needs to be would be determined by the inlet charge temperature.

If this was high enough then the water would vaporize on contact with the hot airstream. If it wasn't that hot, how much advantage would there be to the system?

Any idea what the charge temps' are pre and post intercooler and what point are you proposing to place the atomiser?

As an aside what about using the air con' evaporator and fan mounted in front of the intercooler to give it a blast of chilled air?

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The kit I am going to fit consists of the same bits as you used to fit, except I think the nozzle I am buying in the US is a pretty good one.

They recommend fitting it after the intercooler - I have a Disco EGR-type top hose with the metal pipe in it, so will fit the nozzle to the metal bit somehow.

I don't know what the temps before and after the intercooler actually are, though I have all the bits to monitor the temps.

There was a firm here who used to sell a kit to connect aircon to an extra evaporator between the intercooler and the engine. Personally with that sort of thing I would assume the power gained would be less than the power lost by the aircon. There is very rarely a free lunch in engineering.

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Jim, will you be adding any methanol or are you just planning on straight water?

Gaza

The methanol in aircraft use was mainly there as an antifreeze as it gets cold up there :ph34r: I remember they used to put a nauseant in it to stop idiots from drinking it. That made working on the system a bit nasty, to say the least. Methanol does add a slight bit of power as it burns. But I shall be starting on pure H²O as I am not really interested in more power. And methanol costs money :rolleyes:

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Jim - I've done some reading on this but never turned a spanner in anger on water injection - I believe you can use screenwash as some of it contains methanol? This might be internet hearsay though...

You have my full praise for such a project though, please post up your install and results. If you have a GPS receiver I can help you produce some hard numbers to show any benefits or otherwise.

I tried spraying water onto my intercooler some time ago to keep the temperatures low under prolonged use, when the intercooler tends to 'heatsoak' and lose effectiveness:

[pics resized to sensible size!]

16012006319-copy.jpg

16012006321-copy.jpg

The results were rather disappointing though, the measured torque benefit from the water up a long hill was within the error margin of the GPS kit, around 5% (even if that 5% is real, it probably just about makes up for the extra fuel to cart all that water around! :))

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I do have a GPS receiver, in fact I have two! I use a garmin 12 for navigation and I have a GPSIII which is permanently on and used as a speedo (it can be set to show large numbers).

The water spraying may work better here where it can get very hot, as you know. But 5% in tuning terms is not bad, especially for little outlay.

I do have a 'test hill' close to where I work which gives a steep uphill for about a kilometer, with little traffic. It is difficult to find both.

That 'error margin' does not happen any more - mine can show which parking bay I am in. I think they took it away a couple of years ago.

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If either of your GPS receivers can record your speed into a text file, I've put together a spreadsheet to work out power and torque from it.

Since the US Mil turned off selective availability, the accuracy has been much better but there's still plenty of guesswork about aerodynamics, tyres, hills etc which means you have to do three runs or so and take an average. The units are a little suspect too, but it will show if your LR shows a little more acceleration at a certain engine speed which takes away the 'seat of the pants' guesswork - I was sure my LR was much quicker with the water spray, turned out to be mostly placebo.

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Jim - I've done some reading on this but never turned a spanner in anger on water injection - I believe you can use screenwash as some of it contains methanol? This might be internet hearsay though...

Screenwash does contain methanol, higher % of methanol in winter and different makes will have different amounts. It is fairly common in the US for the diesel pickups to use this.

Gaza

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