Is water-methanol injection worth it?

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Is water-methanol injection worth it? This is the question I have asked myself a few times. In this post, I will tell you why I think it is worth fitting to your car.

First, let me talk about where water injection started. Water injections were used in petrol military aircraft prior to World War 2. Yes, the technology for injecting water into the airstream has been around for many years. This was used to make more power so that the aircraft could take off in shorter distances with more carrying load.

In later years Renault and Ferrari were the first F1 teams to use water injection on their boosted engines. From around 2.5 bar boost they injected water into the air stream to cool down the intake tract.

Over time this system was developed to the point where methanol was introduced into the mix. A mixture of 50% distilled water and 50% Methanol is being used to cool down the intake air and up the octane to race fuel levels.

A downside of watermeth injection.

The only real downside of water-methanol injection I can think of is the fact that you have another tank in your car that you need to keep filled. You can’t just stop at a petrol garage and fill up the tank. You need to keep methanol and distilled water stock at home or in your shop.

Can’t I just use normal tap water?

Yes, you can use tap water. It is not recommended though. I personally have used tap water in my water-methanol mix for a long time. The issue with using tap water is the fact that there is a lot of impurities in the water and also chemicals they use to purify the water. When injecting the mix into a hot air stream the impurities may react and cause a buildup on the nozzle.

This could cause the nozzle to block and you lose cooling. On a high horsepower engine, this could end your engine’s life.

The Upside of watermeth injection.

There is a lot more plus point for water-methanol injection. It keeps the intake temps down which helps to reduce knock. This means you can run more timing which will give you more power. The methanol portion of the mix is not used as a fuel but as an octane booster. This means the knock threshold is moved even higher.

This means in certain instances you can get away with running racing fuel tunes and it will work great. Doing this you will have to run fail-safe systems that will reduce performance if something goes wrong with the injection kit. If not you could blow your engine.

Another plus point is on direct injection engines the water-methanol mix act as a washing agent that helps to prevent carbon build-up on the valves. You may still get carbon buildup but it will be reduced. Just remember the water-methanol is not being injected all the time only from a set point.

Is it worth putting a watermeth system on a naturally aspirated engine?

The power gains are not that dramatic on a naturally aspirated car as a turbo or supercharged car. There are gains though. You know how it is when you drive on a cold misty day or even early mornings. The car just feels strong. Having watermeth injection on a naturally aspirated car you will have that feeling even on a hot day.

At the end of the day, it is for you to decide if you want to spend the money on a kit and buying the fluids. Is the cost per HP really worth it?

On turbo and supercharger cars it is really worth it. Running water-methanol injection you can run higher boost and timing resulting in a lot more power. Here the cost per horsepower is really worth it.

So how is the Watermeth kit controlled?

These days you get different stages of kits. In the end, it is all about how much you are willing to spend on a kit. I am not going to go into what stage is what but only what the different system is you get.

Pressure switch system

Like the heading says. The pump is controlled via a pressure switch. So at a pressure set point, the pump will run at full blast and spray the mix. The upside of a system like this is it is cheap. There is a downside as well. You can only run small nozzles so you don’t get too much mix into the air stream as this is bad for the engine as well. At higher revs, the cooling may be insufficient. This system is an on of system.

Map sensor based system

These systems are your more used systems. They are usually progressive systems. This means when the system kicks in the pump are running at a slower speed. As the boost pressure rises the pump runs faster giving you a bigger volume spray. You can adjust the starting point and at what point the pump must run a full capacity. With this system, you could run bigger nozzles as you have better control over the amount of mix being injected into the air stream.

MAF sensor based system

This system is very similar to the MAP sensor bases system it just uses the MAF sensor reading as an input. You can also set where to start spraying and where to run the pump at full capacity. These systems usually ty into the MAF system of the car.

3D MAP based system

These are the top-of-the-range units and also the most expensive. They have a controller that has the MAP or MAF sensor reading as an input and also RPM. You can map them just like a car ECU. With these systems, you have the best gains as you can map exactly how much water-methanol you want to inject at a specific point. This will give you the maximum gains as you will not have any point in your RPM range that there is too much or too little watermeth being injected.

Some links to watermeth kits & Accessories

Snow Performance Products

AEM V3 Water/Methanol Injection Kit 30-3300

iABED Industries Water / Methanol Injection Plate: A clean solution for adding water/meth injection to your FSI/TSI for Audi, VW

So what systems is out these?

There are a few brands of systems on the market, here are a few in no specific order.

A lot of these systems are similar, so it just depends on what you can get your hand on. None of these systems is a plug-and-play system. You will have to make your own mountings for the pump and tanks. Most of the kit supplies give you what you need to do an install except for the mountings.

What is the best water to methanol ratio to mix?

The recommended mixture is 50% distilled water to 50% Methanol. So other words it is a 1 to 1 ratio. You can pay with the ratio like most people but in the end, everyone comes back to the 1 to 1 ratio. Please just remember one thing Methanol by itself is a very flammable fluid as it’s pure alcohol. Mixed in a 1 to 1 ratio with water it is no longer flammable. Like I said earlier, methanol is not used as a fuel but as an octane booster.

Is a fail-safe a must on watermeth systems.

It all depends on the tune. If you have installed the water-methanol kit on a naturally aspirated or boosted car but not altered the mapping then no it is not necessary.

If you have high horsepower or highly boosted car with specific maps that were done with the water-methanol injection my answer is yes. So if you have a 100 octane map loaded on your car and you run pump fuel with water-methanol injection it is a must.

Why you ask, well if your injection system fails or you run out of water-methanol when under power your engine will start to knock and you will melt a piston or even worse. Protect your engine with a fail-safe system.

Is water-methanol injection worth it?

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