Cold air is good. Hot air is bad. Every gearhead, young and old, is familiar with this line of thinking. We buy hoodscoops, cold-air intakes, and all other manner of contraptions to help feed our engines the fresh, cool air they hunger for. But there is another way to chill the intake charge that’s fairly new on the scene: water-methanol injection. OK, maybe it isn’t that new, as it has roots in World War II-era fighter planes and bombers, but it’s still a technology that hasn’t amassed the street cred it deserves.
To quantify what water-methanol injection is and how it works, we teamed up with the guys at Snow Performance and installed one of their Stage 2 kits on a Chevy small-block with a Weiand 142 blower. The engine, which many of you may remember as project Blown Budget, is based on a Chevrolet Performance 190-horse crate engine we got from Summit Racing for only $1,499. The engine has been upgraded with a Comp roller cam (218/224 at 0.050), Brodix IK200 heads, and the aforementioned Pro Street blower.
The engine made fun, affordable horsepower and the all-cast bottom end had stood up to plenty of abuse (100 dyno pulls and counting). Soon, it would be time to put the engine in a car and run it on pump gas—something the 11 psi of boost in the intake manifold may object to. With a need to bring down the heat from the blower to reduce the risk of detonation and no room under the hood for a conventional intercooler, chemical intercooling with a water-methanol injection system from Snow Performance seemed like an ideal solution. But, before installing the system and engine into a car, we first decided to put it to a little test on the engine dyno.
We drilled and tapped the top of the blower for a 1/8-inch NPT methanol nozzle, which will inject right beneath the base of the carb, on top of the blower. The pump, reservoir, and VC-50 progressive controller were wired and plumbed on a temporary bracket welded up for the dyno test.
Does it Work?
Once at the dyno, the test we came up with was straightforward. We added a temperature probe below the supercharger to measure the temperature of the air in the manifold. After letting the engine warm up, we started logging data. Immediately, we noticed just how much heat the blower produced, with inlet temperatures hovering in the 150-170 degree range at idle. Under a wide-open throttle dyno pull, our peak intake temperature was 169 degrees. Needless to say, this is hot and definitely poses a risk for detonation on pump gas. For our test, the dyno cell was filled with 100-octane Rockett Brand race fuel so detonation wasn’t a concern.
With baseline heat numbers penciled down, we set up the Snow Performance system. The stage 2 kit includes a progressive controller that brings a slew of cool options to the table. Unlike the stage 1 kits that use a pressure switch as an on/off-style of injection based on a specific manifold pressure, the controller allows the user to select a range of injection. Simply select what boost pressure you want the injection to begin at and what pressure you want max injection to occur at. The controller will plot a curve and pulse the injection pump to progressively add water-methanol as boost builds.
With the water-methanol system in place, it was time to put it to work on our hotheaded blower. We primed the air out of the injection lines—an easy job since the controller has a prime button—and made another dyno hit. Again, we monitored inlet temperatures.
We had set the controller to come on at 5 psi and be all in by 11 psi. As soon as we hit the first mark, intake temperatures plummeted like Wile E. Coyote off a cliff, dropping to 108 degrees and holding there throughout the pull. That’s a 61 degree (36 percent) decrease in inlet temperature folks. Needless to say, the system works.
Does Water-Methanol Injection Make Power?
Water-methanol injection is an enabler for horsepower, not a horsepower producer directly. Installing water-methanol injection on a car is like filling the fuel tank with race gas. That one change won’t make any more power, but it opens the door for more aggressive timing and boost—two things that will make as much power as the bottom-end of the engine can take. Also, water-methanol mix is a heckuva lot cheaper than race gas!
After our initial dyno pull with the system on the small-block, we added 4 degrees of ignition timing and picked up 11.5 horsepower and 21.4 lb-ft of torque. The engine had already been tuned for 100-octane, as that is what Westech usually runs in the dyno cell. If it had been tuned for pump gas, the gains would have been even more impressive, as there would have been a lot more timing left in the tune-up.
On late-model cars, the timing is advanced or retarded based on input from a myriad of sensors and various maps built into the ECU. Adding water-methanol injection on those vehicles CAN actually produce power without any other changes as it spurs the computer to use a map built for colder air temperatures.
“With some newer cars, the colder air temps move the computer to a new part of the map,” said Matt Snow of Snow Performance. “It [the ECU] senses the cold air and adds timing.”
How Does Water-Methanol Injection Work?
The idea behind water-methanol injection is simple: more effective octane and colder intake air temperatures (IATs) suppress detonation and allow more boost and ignition timing to be utilized for an improvement in power.
To understand how chemical intercooling with water-methanol works requires a quick science lesson. By spraying a fine mist of a mixture of water and methanol (usually 50/50) into the intake of an engine, a huge amount heat can be removed from the incoming air. The reason for this drastic reduction in temperature is a thermodynamic property known as latent heat of vaporization (LHV). Any time a substance moves from one state of matter to another, such as from a liquid to a gas, (this is known as a phase change) energy—in this case heat—is transferred. Every substance has a specific LHV, meaning a unique amount of energy per unit of mass, it can absorb during a phase change. This is measured in kilojoules per kilogram (kJ/kg). Water (2,257 kJ/kg) has double the LHV of methanol (1,100 KJ/kg), but both are fairly high on the scale. For a frame of reference, acetone has an LVH of only 518 kJ/kg.
As the mixture of water and methanol mists into the intake, the scientific dream team of water and methanol comes together, rapidly shifting from liquid into vapor and pulling heat seemingly out of thin air. The methanol component of the mixture provides a significant boost in effective octane, while the water does the brunt of the cooling work. Science lesson over!
How Much Meth is Too Much?
While your high school counselor would adamantly declare that no amount of meth is OK. We’d argue that in the automotive world, it’s pretty great. So, if some water-methanol is good, more must be better, right? Wrong.
“The number one misconception that people commonly have with methanol is that it’s like nitrous, where the more you put in the more horsepower you make,” said Matt Snow. “What happens is you can end up quenching combustion, like throwing a bucket of water on a campfire. There is a sweet spot where you don’t quench combustion but you give the engine all of the cooling and effective octane that you can get. That allows you all the timing and boost to play with for additional power.”
So, how do you figure out the ideal amount of methanol for your combination? Matt recommends adding water-methanol then trimming it out until you don’t lose any power and get back to your original baseline dyno. From that point you can begin to add timing and build power. “If you’re losing power, you’re quenching and blowing the flame out in the combustion chamber,” said Matt. “Keep adding timing until the engine stops making power then back it out a degree or two.” He also recommends gapping the plugs down when using water-methanol injection.
What Fluid Should Be Used?
Water-methanol injection is a balancing act between charge cooling and the addition of octane. The water component brings the charge cooling with its sky-high LHV, while methanol supplies the octane portion of the equation. For that reason, it’s been determined that a 50/50 mix is ideal.
Can you run pure methanol? The answer is yes, but Matt Snow points out that it is not recommended. “Methanol is pretty flammable stuff when you take the water out of it,” he says. “It can become a danger. Also, methanol has more effective octane, but it won’t have as much cooling potential as water.”
One of the other uncertainties that Matt helped clear up is the use of windshield washer fluid. While the idea of pouring that blue-Gatorade-looking substance into your engine may seem absurd to many, Matt points out that it actually does work.
“It’s so cheap and easy to get everywhere you go,” said Matt. “I’ve used it in a pinch and filled up with -20F washer fluid, which is about 33 percent methanol and it does great. I’ve beat 110-octane race fuel with windshield washer fluid on top of pump gas.”
Boost Juice, Snow Performance’s home recipe of 50/50 water-methanol offers more octane potential with its higher methanol content, but should you run dry at the track, -20F washer fluid will keep you in the game.
Conventional or Chemical Intercooling?
One of the strong points of chemical intercooling with water-methanol is that the system is compact and easy to install. If you have a turbo or supercharger system in your car and not a whole lot of underhood real estate to package an air-to-air intercooler, water-methanol injection makes a lot of sense. Chemical intercooling substantially cuts down on the amount of plumbing needed in a forced-induction system and also doesn’t restrict airflow like many conventional intercoolers do. With the exception of some of the massive ice-bath, air-to-water systems that are used in pro drag racing, water-methanol injection also offers more charge cooling capability.
So whether your engine is blown; nitrous-fed; turbocharged; or even high-compression, naturally aspirated, water-methanol injection is another great option to help it chill out.