water injection

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Does anyone on here have any experience of water injection? I believe it is usually fitted to forced induction engines, but am curious to know if it is of any use on a n/a engine. I have a '87 Lotus Excel with twin dellorto carbs and am looking for a cheap way of improving the power and efficency. i am aware of nitrous / nos and aftermarket turbos etc. but am interested in this due to its apparent simplicity...i obvioulsy stand to be corrected on that.

posted by  hammerthief

Water injection is used on anything with a higher compression ratio that doesen't allow you to run on street gas. It doesn't icrease power or efficiency, it lowers both. Just think about it, you're shooting water into your cylinders to lower the temperature, the engine is run off that heat that the water is desipating, decreasing everything. It wouldn't do jack to your vehicle other than hurt it. It's generally only used in racing applications.

posted by  88GrandPrixSE

I have a couple of questions leading on from your post. If it doesn't increase power or efficiency, why would you use it on a race car? surely the last thing you want is to reduce power? Why was it used in Spitfire Aeroplanes in the war, surely as they rushed up to fight ME109s, they didn't turn on the water injection to slow themselves down? You are right about one thing i do want to decrease air intake temp...i want as great a difference in temp from cold air going in to hot air as cold air will expand more as it heats increasing power and efficiency...which is why turbo cars run intercoolers....i did ask for people who had experience of water injection....Sorry but i think you are either misinformed or need to read up some more. Ever driven a car on a misty morning and felt the extra power? you can't see 20m in front to use it but its there....i don't think running a car on a misty day damages it or we would all hear alot more about it...

posted by  hammerthief

I'm very well informed, my whole family is in the racing industry.

Okay, you know how octane works right? Basically the higher the rating, the harder it is to combust, right? Well, what water injection does is almost like what a can of octane booster will do, almost. It's like you just boosted the octane, it stops the fuel from detonating early due to high compression (which your car doesn't have), but unlike octane booster, due to the fact that it's well, water, it reduces efficiency.

What it does for race cars is allows them to run lower octane fuels. So if your vehicle is running extreme compression, that even 120 won't suffice for, they inject water to cool it down and water doesn't burn so, it also raises the temp required to combust.

As for cooling the air, it doesn't exactly work like that. It's injected right before the cylinder, or in some cases, directly into it. To make a difference the air has to be cold before entering the cylinder.

You don't get any boost in misty weather... if anything it will hurt your output. Reasons:

1) Air filter stops almost all mist
2) Due to moisture on filter, air has harder time passing
3) It just does not make a difference on a production car

People seem to have the idea that the higher the octane you go, the more power you make, it doesn't work like that, if you do that, you will easily hurt your power. Production vehicles are 99% of the time made to run off 87 octane (burns hot), but some people put 91 (burns colder) in their car that's made to run 87, you're losing power. I don't know how to explain it any better than that.

Water injection is made to prevent knocking, not to give you more power. You car is made to run off 87 octane fuel, water injection would make you lose power, and drain your pocket.

posted by  88GrandPrixSE

[QUOTE=88GrandPrixSE]I'm very well informed, my whole family is in the racing industry.

thats interesting...do you have any actual experience of water injection? its banned in most race series, so just wondering what you have seen it fitted to.


You don't get any boost in misty weather... if anything it will hurt your output. Reasons:

1) Air filter stops almost all mist

don't have air filters...four inlet trumpets...

2) Due to moisture on filter, air has harder time passing

see above

People seem to have the idea that the higher the octane you go, the more power you make, it doesn't work like that, if you do that, you will easily hurt your power. Production vehicles are 99% of the time made to run off 87 octane (burns hot), but some people put 91 (burns colder) in their car that's made to run 87, you're losing power. I don't know how to explain it any better than that.

Excel (high compression engine) was designed to run on high 98 octane fuel and never on standard unleaded, my car still hasn't been run on standard unleaded as i would have to change timing from what it was designed for so been using LRP (getting harder to find)and boosting octane to get 98.., so water injection if it does as you say would enable me to run unleaded fuel and this would not hurt my pocket...

I could spend a few hours ripping the rest of your post to bits but thats not helpfull, but thanks for the effort you made.
To be more helpfull you could answer a couple of questions
Have you seen and experienced water injection in either turbo/supercharged cars? have you any experience of it at all?.i don't mean a google search...

posted by  hammerthief

I have some experience with it yes, not me personally, but a guy my father used to work with/race with. He currently holds the NHRA record in a certain class, forget which one though, he races a blue 99 grand am, that's all I remember. He runs water injection, that is where I got all my info from. Since car performance is his job, I'm pretty sure he's a much more reliable source than wherever you're getting your info from.

posted by  88GrandPrixSE

A bit of a contradiction..you have some experience..but i don't really!!!
so your dad knows a guy that holds a record but you have no idea what? golly i bet you must be proud..and he must be pleased you take so much notice of what he does...of course you should listen to your dad i wouldn't presume to say otherwise..i don't know which info i have which you disagree with....

but at least you told me something i needed to know, it could well do what i want it to do and allow me to run unleaded fuel...trouble is should i trust info from you? bearing in mind you can't have seen my type of car and have no actual experience of the system i am asking about..but thanks for your time i do appreciate it..perhaps someone who has actually got a system or has worked on a car with it might help?

posted by  hammerthief

When you say water injection your are really talking about a water/alcohol mix? If so then yes they are used on high performance N/A, but mainly forced draft engines to provide adiabatic cooling and lower combustion temps. This allows you to optimise your timing and keep the fuel closer to stoich, rather than running retarded and rich.

I had a friend who ran water injection on N/A, mainly for economy reasons and it was a bit destructive on the metal. A couple of members on another board are currently testing it to see how it behaves on their cars running 25 plus pounds boost.

posted by  Wally

Thanks Wally, yes a water alcohol mixture, i believe ethanol is prefered? Destructive on the metal? you mean the cylinder linings? Does it effect Nickersil coated as much? I don't suppose you might send me a personal message to say where this other board is would you?i suppose my Lotus was a performance car in its day but comparitivly slow these days..sounds like its wha ti need to run the unleaded fuel :clap:

posted by  hammerthief

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