Methanol injection is growing in popularity, mostly because of it's relatively low cost, but also because it's a performance add-on OR a fuel economy add-on, depending on tuning. The concept is simple: inject a mix of water and methanol into the air intake of an engine with forced induction. The mixture has a cooling effect, which increases air density and leads to an (effectively) higher boost pressure. Depending on tune, a water/ethanol injection kit will boost horsepower 5-20%, with potential for a small increase in fuel economy as well.
If you've got a turbocharged VW or Audi and you're thinking about water/methanol injection for your vehicle, this post will walk you through the basics, as well as list some pros and cons.
How Water/Methanol Injection Works In Detail
The basic principle:
-As turbo or supercharger boost pressure is increased, the temperature of the intake air increases along with it. High boost pressures lead to high intake air temperatures.
-As air intake temperature increases, exhaust gas temperature increases as well. At some point, exhaust temperature becomes so high as to risk damage to the turbocharger or engine damage due to pre-ignition/detonation. At the point where turbocharger damage or pre-detonation is possible, the amount of fuel that can be burned in each cylinder (and power that can be produced) is constrained.
-One way to alleviate this constraint is to install a physical intercooler to cool the intake air temperature (and therefore exhaust gas temp). However, physical intercoolers can only do so much.
-Liquid intercooling - which is essentially what a water/methanol system does - reduces the air intake temperature by spraying a fine mist of water and alcohol into the intake airstream. This mist than absorbs heat as it evaporates. Lower intake air temps reduce exhaust gas temps and also reduce the chance for pre-ignition/detonation.
-Reduced air intake temperatures allow for more fuel to be burned, which means more horsepower!
TL;DR; Water/methanol injection essentially increases boost pressure. More boost = more power, as this video shows:
Water/methanol injection systems can be installed on any vehicle with forced induction. In the Audi/VW line-up, this includes both turbocharged gas engines and TDI diesels. Depending on the water/methanol kit you install and the type of vehicle you have, you can add +50 to +100hp. Since these kits are fairly simple (in terms of components), they're affordable. Most kits cost between $500 and $1000, with more and more kits becoming available at the $500 price point. Installation is typically easy enough for most DIY enthusiasts to tackle.
Is Methanol Right for Your Vehicle?
A lot of people get nervous when they hear about injecting water and/or methanol into an engine. However, the concept is proven (water and methanol injection has been in use on aircraft engines since before World War II), and with modern engine management systems the odds of damage are low.
Here are the specific pros and cons of water/methanol injection systems for Audi and VW vehicles:
Pros
Low cost. You can add 50-100 horsepower to your engine for as little as $500 (often less)
Increased engine efficiency. Depending on how the engine is tuned, a water/methanol injection system can often increase both horsepower and fuel economy (at least a small amount 5-10%).
A cleaner engine. A water/methanol kit basically steam cleans the valves, valve seats, piston tops, and intake — thus reducing carbon buildup.
Easy installation. These kits usually be installed in a few hours. Assuming they're designed for your specific vehicle, the install is often about as complex as adding a performance air intake like this one.
Cons
There are very few cons to a methanol kit. Most of the problems that can arise stem from an installation error, particularly on custom systems that must be modified for your specific application. For that reason, it's a good idea to pay a professional to install your water/methanol injection kit unless you're comfortable with this type of work.
Otherwise, the cons are:
Refilling the water/methanol tank. Many systems allow for a range of water and methanol mixtures to be used, but not all. If your water/methanol system requires a very specific mixture, you may have to buy an expensive custom mix. Otherwise, you can often run windshield washer fluid (which is a 70/30 mix of water and ethanol). Be sure to check and see what type of water/ethanol mix you need before you buy.
Engine damage, at least in aggressive implementations. Most of the standard "stage 1" or "stage 2" implementations are mild. They add 50-100hp to your engine, but they don't inject so much water or methanol into the air stream to cause problems. But if you're trying to add a stage 3 or stage 4 kit, you risk engine damage if your settings are wrong, or if you have some sort of fuel injection system failure.
But again, this is only for aggressive implementations. If you stick to a mild tuning setup, you'll still add LOTS of power for a good price.
Installation Tips and Info
Finally, some more specific details that will help you with install:
-Take your time choosing a size and location for your water/methanol reservoir tank. It should be big enough to last at least as long as a tank of fuel (assuming that you activate the system infrequently), and it should be easy to access so you can refill.
-Make sure you understand when the injection starts to occur. Some kits begin injecting water and methanol at 4psi, other kits don't inject the water/methanol mix until just before WOT.
-Make sure you research the fuel mixture possibilities before you buy. The last thing you want is a water/methanol injection system that requires a proprietary fuel mix.
-Read the instructions! That's the best way to know how to modify your engine tune without causing damage.
Like we said, water/methanol injection kits are getting more popular on turbocharged Audis and VWs. They offer considerable performance increases and - when installed correctly - very little risk.
