Water Injection

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demag
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Water Injection

Post by demag »

About thirty years ago not long after I got married[:I] I was working as a chauffeur/mechanic for Brockhouse Engineering in the Black Country. We had three or four XJ6's there, 3.8's and 4.2's.
The md somehow got to hear about some bloke from Stourbridge who fitted water injection systems to cars and claimed the mpg went through the roof. The Express and Star actually devoted a large article to him and did a controlled (ish) test on a Mini Traveller with very impressive results.
Well they got this fellow to come to the company garage and fit one of these systems to the md's Daimler 6. I'd read about them in car mags but had never seen one. I must admit the way he fitted it was quite impressive.
Firstly, he removed the exhaust manifold (weren't they in two on the Jags, I can't remember now). Then he drilled and tapped it to take two olive fittings. Then he fed a fair old length of 1/4" stainless tube in and through the manifold and back out again. Then one end was fed into the air filter housing and the other end was connected to an old SU remote float chamber which was fitted to the inner wing. A plastic remote radiator header tank was also fitted to the inner wing at a higher level. I think that was off an Austin/Morris 1100. Then another piece of pipe connected the header tank to the float chamber and that was it! Needless to say it took a few hours to install this lot.
To be honest I didn't notice much of a performance boost (difficult to tell on a 4.2 Daimler). But, The fuel economy was phenomenal! Bearing in mind we are talking 4.2 three speed auto here with the old Borg Warner box which by no means of the imagination would you call advanced. Average around the West Midlands area was about 15mpg which would increase to the low/mid twenties on a run to Heathrow. Well all of a sudden this thing was doing mid twenties around the town and mid thirties on a run with no change of driving style![:0]
There was enough water in the header tank to last several hundred miles and it was only topped up fortnightly. By the time the water had gone through the exhaust manifold it must have been superheated steam entering the engine but it was enough to raise the efficiency and mpg of the engine.
The bloke then had a brainwave and substituted the water for methylated spirit, apparently to boost performance even more. But that was when it all went wrong. I am afraid I failed my physics "O" level but have it on good authority that when you boil meths, cos that is basically what was happening in the exhaust manifold, it turns to pure carbon and blocked the pipe solid!
But he had proved that a simple technique such as this had the effect of transforming fuel economy in any car. He approached Rover many times with this (Leyland in those days?) but they weren't interested. I don't know what happened to him after or if he coverted many more cars.
Might be something worth thinking about in these £1/litre days. If anyone decides to 'ave a go then let me know how you get on.[:)]
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Post by ssray »

diy water injection here http://transportation.hackaday.com/entr ... 393047637/
thinking about it for my hilux surf(19-25mpg)
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Post by FrenchLeave »

Veeerrry interesting!
High performance piston engined aircraft used to use water injection to cool the charge after supercharging, thus increasing its density; but this was done simply to increase power. Methanol injection was also used for the same purpose. I don't think it did anything for fuel consumption though.
I'd love to try it on my XM V6 but the thought of trying to get the exhaust manifolds off puts me off!
I assume this doesn't apply to diesels, so which petrol head is going to give it a go? Please?
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Post by FrenchLeave »

Typical - I put my post in before I read ssray's link! However, the link seems to relate only to turbocharged cars whereas the engines that demaq wrote about were all normally aspirated.
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Post by bxbodger »

I wouldn't have thought it would be necessary with modern turbo cars because they have intercoolers-a much less elaborate arrangement than water injection, although I can see its point on an old type supercharger arrangement.
I can't see how it would make a Jag more economical though......maybe it was running so rich already that the added water leaned it off a bit!!
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Post by Kowalski »

This is quite a good write up of water injection.
http://en.wikipedia.org/wiki/Water_inje ... engines%29
If there were big benefits to be had, it would be done, I think there is only an advantage to it if you're running a lot of boost on a petrol engine. I heard a while ago about a company experimenting with it on buses but the engines didn't last very well at all by all accounts.
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Post by FrenchLeave »

Yet demaq is writing from personal experience.
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Post by Kowalski »

A lot of the water injection kits I've seen introduce an air leak into the inlet manifold somewhere, and thats where your fuel economy gains come from, just like an ecotec valve does.
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Post by demag »

I think what made the difference was the water (steam?) increased the density of the charge in the cylinders. Hence the increase in performance/mpg. Aren't I right in thinking they use it on F1 cars, probably a hell of a lot more sophisticated now though. Looking at ssray's link above shows just how far it's been developed. But from my own experience it's fairly obvious you don't have to have a cpu controlled unit and a "Blue Peter" approach is capable of coming up with the goods.
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