Water injection

Hello All, I hope you might advise me on a small project I’m planning.

I’m always keen to explore ways to enhance economy and not loose performance. What I have done to my 1.8 FL1 seems to work very well and I’m getting a steady 31mpg with regular mixed use and nearly 38 mpg if I take care on a longer run.

I’ve been reading up on water injection or water/methanol injection on petrol motors. Benefits include cooler cylinder / engine operating temp, greater power output [due to increased volumetric efficiency], enhanced octane rating, anti knock, lower pollutants out, a cleaner motor…

There are kits available so the cost needn’t be great. I’m interested to see if I’d gain some more mpg and perhaps better low end torque.

Some questions which you may be able to shed light on.

If I use water injection can I use a lower grade fuel? Currently in NZ we have a choice of two at the pump, both unleaded 91 and 95. I use 95 at present. Water injection boosts the octane rating of a fuel and acts as an antiknock agent - could I safely use that lower octane fuel and suffer no ill effects?

Will the ECU adjust the timing to match the fuels characteristics?

Will the ECU be able to adapt for the altered exhaust gases which will contain increased oxygen? I’m not sure what will happen - either more fuel added due to cooler operating temp and increased oxygen out or possible less fuel?

Thanks everyone.

It is a good idea to add a water injection system, a clean oil to keep the engine including the exhaust manifold and intake will and clean + better cooling to the piston head.
An increase engine performance and lower fuel consumption.
ECU will have no problems with the fuel air mixture

success...

you'd lose mpg dragging the 20ft water container around with you

Surely if this idea had any real benefit motor manufacturers would fit it.

Water injection is not uncommon in hot countries. I believe taxi's in Australia use it.

Water injection (engine) - Wikipedia, the free encyclopedia

Richard Martin said:

Surely if this idea had any real benefit motor manufacturers would fit it.

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Richard Martin said:

Surely if this idea had any real benefit motor manufacturers would fit it.

Click to expand...

Indeed they have in the past [1960s USA / Oldsmobile F85 fitted with Fluid-injection Jetfire!] & WWII fighter aircraft and jet engines too. It’s used to cool the incoming charge and acts as an anti-knock agent. Commonly fitted to high performance Turbo’d motors, and fitted to large capacity normally aspirated engine as well. Diesels can benefit too. Current uses are for high revving engines where excess heat and preignition are problematic. Water/methanol injection target this and enhances cooling and thus power.

I’m wanting to know in what ways it would benefit a regular motor. Cooler air in = more oxygen, steam created = increased volumetric efficiency [ + a cleaning effect], anti knock so a lower RON fuel could be considered = cheaper running costs. Overall it’s more bang for you $ [or £ ].

If I fit a system, be it a simple one, would I see increased MPG? improved low end torque?

I’ve seen that timing can be advanced to cater for more efficiency at lower rev ranges. Combine the above with some carefully adjusted cam timing and there could be some interesting gains to be had.

Discussion welcome, Consider how ECUs will adjust / cope or not, emissions should be better as the motors produce less NO2. I would not need to cater for activating the system at predetermined pressures as per the turbo vehicles.

Water tank needn’t be 20L - I estimate 3 to 5L for our small motors and that may last each refill. You could even use the screen washer bottle which is there already!

I love to tinker and explore and am always keen to hear others experience and knowledge.

PS In the past there have been a variety of interesting things invented to enhance fuel economy, Anyone ever heard of the Dieselbec? A device which heated diesel fuel and enables a petrol motor to run on it - WWII initiative, Pogue super Carb’ used by US Army to extend the range of tanks - WWII, or even The pantone engine [ lots of debate on this one!] a modified induction system which incorporates its own ‘cracking’ system - allowing a wide variety of fuel mixes to be used [ pickle juice, water, crude oil …] and it reuses its own exhaust gases - minimal pollution produced!!

it's usually used for top end power so it's not constantly on.. where are you coming up with 3-5l and how long is that for?

trax said:

it's usually used for top end power so it's not constantly on.. where are you coming up with 3-5l and how long is that for? a

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True, top end power in high performance forced induction engines where rev's, pressures and temp's are high and thus the cooling and anti-knock properties are needed. But how would it work if fitted to a K series 1.8 to boost mpg and maybe low end power?

It could be installed to add a mist of water to the incoming air [before the throttle body] only when the throttle is open ie: power is on required.

Size of water container is essentially irrelevant you would try to match it to your fuel usage patterns, by that I mean when you fill up with petrol you'd also fill up with water / water-methanol too. So the container could be as small as 3L of as big [as has been suggested as 20ft!! but that may be over kill?] 5L perhaps bigger.

haha, yeah i was kidding about the 20ft.

you'd need to do a lot to try it properly. you will be able to work out water consumption via the jets and pump rate.

but keeping the ratio correct as you add more juice will take some custom maps or controllers. it could be an interesting experiment, but i don't think any gains would be financially viable tbh.

have a go if you fancy it though!

I seems to me that the cooling effect could pose a problem. The whole ECU - Motor system works well in st’d set-up. With a mist of water being introduced this will cool the fuel/air mix. Would the ECU detect this? It could be like a cold start situation where the ECU sees the incoming air temp and coolant temp and adds extra fuel to get things going.

Would the ECU over fuel the motor erroneously believing inlet air temp to be near a cold start situation - even though the coolant temp would be in the normal operating parameters?

Adding H2O to the fuel/air causes a greater amount of oxygen to be present in the cylinder/exhaust, in effect leaning out the air/fuel mix. Will the ECU compensate and add fuel?

Will it also adjust the spark timing and injector timing to better suit the new conditions?

Mine is a '98 FL1 with the K series 1.8. I've mod'd the intake & exhaust as well as the head.It has the MEMS 1.9. MEMS 1.9 isn't adjustable / remap. Is the latter MEMS 3? This may be a thing to try out on a latter ECU vehicle if it is able to be re mapped.

I'm a bit late to the party on this one. To many things on the go I guess.
Water injection on a NA, K series would be a waste if economy was your main aim. The reasons are these.
1 The MEMS system has fixed ignition timing. I don't mean fixed as in no advance/ retard but fixed at a preset maximum advance. There are no knock sensors fitted so MEMS is deliberately set slightly retarded from optimum for maximum power / economy.
2 The cooling effect of the water can reduce the induction temperature. This will mean that the fuel doesnt vaporise, this would stop the fuel burning as cleanly as it should. This could well effect the economy in the wrong direction.

Rather than add extra complication and weight, why not optimise the cam timing then get the ECU calibration spot on with a remap. This would see better economy gains than adding water injection.
The very best economy available to you would be dump the cat and map the engine to run lean when cruising. This would gain you 15 to 20 % better MPG with no complicated water injection. Don't forget, for a cat to work correctly, the engine has to burn fuel at the stoichiometric ratio of 14.7 to 1. For maximum economy, fuel ratios can be closer to 23 to 1 are needed. The fuel saving gains are easy to see.
The oil companies knew this when the cat was first suggested back in the 70's. The only people that benefit from the cat are the oil companies and the various government tax departments. The car burns 20 % more fuel because the cat requires it to work correctly. The engine produces 20 % more CO2 than it would without the cat.
So unless you are mandated to have the cat, dump it.