More Power, Less EGT, and Greater Reliability

More Power, Less EGT, and Greater Reliability

Perhaps some of the most underrated performance parts in the industry are water-methanol injection systems. On street trucks, a well-tuned water-meth system can be worth 75 horsepower or more, as well as a drop in exhaust gas temperatures of 100 to 300 degrees. In competition applications, huge engine-driven water injection systems can reduce exhaust gas temperatures by up to 1,000 degrees and also allow for more aggressive tunes. So—it’s safer—with more power? That is correct. 

How Water Injection Works

As an engine makes more power, it also makes more heat. Eventually, combustion temperatures and exhaust gas temperatures, EGT, can reach dangerous levels, and that’s where water injection comes in. Even with efficient intercooling, diesel engines found in high-horsepower street applications or racing vehicles will still need additional cooling. When water is injected into the engine, it is converted to steam, and when this happens, it absorbs an enormous amount of heat out of the air. This function is called the latent heat of vaporization, and reduces both combustion and exhaust gas temperatures without having much of an effect on power.

Adding Methanol to Create Water-Methanol injection

At some point, an innovative gearhead figured out that you could make some extra power with water injection just by mixing it with methanol. Not only does methanol have a latent heat of vaporization value all of its own, it also is a fuel, so it makes power when it is injected into an engine. Since diesel engines are compression-ignition engines, introducing a fuel into the intake may seem dangerous; but that’s the beauty of the water-methanol mix. If 100-percent methanol was injected into a diesel, either a dangerous backfire, or engine-damaging pre-ignition (which normally isn’t possible in a diesel) would occur, resulting in some fried parts. The water component in water-methanol injection acts like a detonation inhibitor, and keeps the methanol from auto-igniting under the high compression temperatures of a diesel. While it seems that a 50/50 mix is a good safe ratio for cooling and power, we have heard of folks going as high as 70 percent methanol, which sometimes works (lots of power) and sometimes doesn’t (engine damage).

1 This Banks Straightshot water-methanol injection kit is a good example of a modern state-of-the-art system. It comes with a tank, lines, wiring, controller, solenoid, pump, EGT probe, nozzles, and all the fittings necessary for installation.

Street-Oriented Water-Methanol Injection Kits

Adding fuel is the easiest way to extract more power out of a street-driven diesel, and even with just basic tuning, exhaust gas temperatures can reach the point where they are at dangerous levels. A stock Duramax engine for instance, will only generate about 1,300 degrees of exhaust gas temperature (which is safe) but we’ve seen tuned engines that have peaked at 1,800 degrees or even higher. With this type of heat, it’s only a matter of time before damage occurs.

“On street trucks, a water-meth system can be worth 75 horsepower or more, as well as a drop in exhaust gas temperatures of 100 to 300 degrees”

While increasing turbocharger size or intercooler efficiency is a good way of keeping exhaust gas temperatures under control while adding power, we’ve also seen good results with water-methanol injection. With a 50/50 mix, average gains in power are usually between 35 hp and 75 hp, with a 150 to 300-degree drop in EGT. Having these systems triggered at part throttle on aggressive tunes can also result in greater towing speeds, as more throttle can be applied, while keeping EGTs in or below the 1,200 to 1,300 degree “safe” zone for diesels.


Injecting a bunch of water or a water-methanol mix at low boost or rpm can result in “snuffing” the engine out. Essentially, there’s too much water compared to fuel and air, so the engine stops running. With this in mind, builders have integrated different forms of control into water-methanol systems to ramp up the level of injection as boost and rpm rises. The simplest form of activation is a pressure switch, like a Hobbes switch, which will trigger the system at a certain pre-set amount of boost. Up from there are throttle-position triggers, digital controllers, and boost and EGT-based systems.

2 A small arming switch can be used to activate a water-methanol system manually, and can often be placed in an unassuming spot, like the bottom of a dash.
3 If you’re just looking for an extra burst of power and don’t need much capacity, a stock windshield washer reservoir can be used as a water-methanol tank. The red fluid inside is Boost Juice, a 50/50 pre-mix from Snow Performance.
4 When towing, using at least a 5-gallon tank is a good idea, as the last thing you’ll want is to run out of cooling on a long grade.


Injection systems vary in flow, controls, and options, and you’re probably not going to need a sophisticated multi-stage system just to cool down an old IDI for towing use. By the same token, a street-based kit probably won’t be enough for a 1,500 horsepower sled puller, so matching the kit to the application is an important part of selecting a system.

“In competition applications, water injection systems can reduce exhaust gas temperatures by up to 1,000 degrees”

5 One of the main components to a water-methanol system is the high-pressure pump, which creates about 200 to 300psi on street-style kits. It should be mounted below the tank and as close to it as possible.

Is Water/Methanol Injection Right for Me?

There are plenty of diesels in the 300 to 500 rear-wheel horsepower range, and water-methanol injection will work quite well on just about every one of those trucks. In competition applications, we’re surprised more folks outside of sled pulling (like fast-street and drag trucks) don’t run water or water-methanol systems, as replacing pistons, turbines, and other hard parts get expensive. If you’re looking for a little extra power or cooling, a water-methanol injection system might be just what the doctor ordered for your diesel. DW

6 Nozzles are usually mounted in the intake post-turbo, and can even be disguised fairly well. Most hot street performance systems use two large nozzles, such as these two 625 ml/min units from Snow Performance.
7 The ultra-high pressure water or water-methanol is injected into the intake stream of a diesel engine as a mist, which is then swirled into the engine for cooling and combustion.
8 Very sophisticated controllers are available for use with modern water-injection systems. This control interface from Banks is a simple 2 1/16 gauge unit that can be used to command two stages of injection. It also displays boost, EGT, throttle position, flow and can be adapted to factory MAP sensors.
9 Simple boost-based systems can be especially effective on older trucks. On an early VE-pumped Dodge, we saw a 35-hp gain at peak power, but past 3,000 rpm the truck picked up nearly 70 horsepower, as the methanol in the system carried the power band out further as the diesel fuel pump defueled.
10 Nitrous can be particularly hard on a diesel engine. The immense heat it creates can be calmed down by water injection, and turbine damage can be avoided with a healthy dose of water in addition to the nitrous.
11 An interesting mid-step between all-out competition kits and street-based systems is this large electric kit from Scheid Diesel. The simple boost-based setup can be adjusted to trigger at 40 to 60psi, and provides 600psi of pressure. It’s recommended for trucks in the 1,000 to 1,500 flywheel horsepower range.
12 Diesel World Editor-in-Chief Adam Blattenberg has been testing the Snow Performance Stage 2 kit for years on his 7.3L, and has seen nearly 50rwhp on the dyno and a good 2 to 3mpg boost in average fuel economy, thanks to the water-methanol mixture being ramped in at very low throttle positions (like highway cruising). While towing roughly 10,000 pounds in a modest tune, EGTs have never gone above 1,000 degrees while climbing large grades at 65 MPH.
13 Another example of a well-tuned water-methanol system is the twin-nozzle kit on Jerry Allen’s ’05 Chevy. On the dyno at Brown’s Diesel, a hand-mixed water-methanol mixture of “a little more than 50 percent” was worth nearly 60 rear-wheel horsepower.
14 Three nozzles from Snow Performance seen here in the cold side intercooler tube.

Competition Kits

High horsepower applications have their own unique set of problems when it comes to cooling. When it comes to trying to keep exhaust gases under control on a 2,000 to 3,000 horsepower diesel, a lot of water has to be injected into the engine, well past what most street kits are capable of delivering. While pickup truck systems may inject water at 200 to 300psi, it’s not uncommon for competition water systems to run at 800 to 1,000psi, with up to 12 delivery nozzles. If a water system fails in this type of application, EGTs can rocket past 2,000 degrees in a matter of seconds, so water injection is an integral part of keeping these engines alive.


Banks Power

Scheid Diesel


Cooling Mist

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