Want to run 5-10 PSI more boost then you are now? Sure you do, unless of course you’re opposed to adding 50-100 hp to your car. With alcohol injection you can do just that, all while buying your gas from the pump. I’ve been a huge fan of alcohol injection for many years now. Personally, I don’t see why everyone isn’t running some type of supplemental injection. Not having to pay outrageous prices for race gas will pay for your kit within the first year.
Using alcohol injection is all about increasing your effective octane ratio. This means understanding the octane to compression threshold or knock threshold of any given fuel as well as the terms pre-ignition and detonation.
If you aren’t familiar with detonation and pre-ignition I suggest you read https://www.nicoclub.com/archives/detonation-preignition-tuning.html for a detailed description of both.
I’m going to use 91 octane pump gas as an example since that seems to be the highest and most available nation wide. When adding a turbo or increasing the boost on a vehicle that is turbocharged from the factory, we are greatly increasing the compression of the motor. So what determines the amount of boost we can add before the motor goes pop? This is where we talk about the knock threshold. If you add boost, you need to add fuel. That part is simple, more air + more fuel = more boom. So why can’t we just install huge fuel injectors and run 30 psi? Because every fuel has a point where it auto ignites and 91 octane reaches that limit far before we ever see that 30psi. The octane rating is a measure of that particular fuel’s resistance to auto ignition. The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions. There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel’s knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON. As an example, Toluene has a RON octane rating of 124 and a MON rating of 112, leading to a (R+M)/2 rating of 118. (R+M)/2 is how ordinary fuels are rated in the US. The correct name for the (RON+MON)/2 formula is the “anti-knock index”, and it remains the most important quality criteria for motorists.
What does all that crap mean? If we increase our effective octane ratio we can add more boost. The biggest reason alcohol injection is effective, is the increased octane it has over 91 pump gas. Let’s use Methanol as an example. Methanol (Meth) has a (MON) rating of 105. So when Meth is sprayed into the intake it effectively raises the octane of fuel that is injected into the combustion chamber. More octane = more boost. There are several very good chemicals that can be used for this. Methanol is definitely one of the more popular ones, but you can use Denatured Alcohol, rubbing alcohol, Ethanol, E85, Toluene or any of those mixed with water. Water in itself IS NOT a means to increase your octane. However, when injected into the motor, it evaporates upon entry into the combustion chamber absorbing lots of heat as it does so. This allows our 91 octane fuel to remain stable even at higher boost levels.
Before we can really get into tuning and the effects of the different chemicals we can choose from, we have to understand the various injection options available to us. There are literally tons of options available today, ranging from DIY setups consisting of a spray nozzle, pump, fuel line, pressure switch and reservoir all the way to $1000 setups that are closer to running a full standalone computer. It’s up to the individual what avenue they choose for themselves based on budget and power goals. I’ll explain the 3 most common setup’s used today and the tuning involved with each.
As you can see it’s a very simple design made up of a pump, some jets for tuning and the necessary lines, relay, pressure switch and reservoir. The idea behind this as well as most other basic kits is to provide the user with a kit that is easy to install and tune yet functional and affordable. The tuning of a single stage kit is fairly straight forward. First you need to install the kit according to the instructions included with the kit at the time of purchase. If it’s a DIY setup, then you’re on your own as far as the install goes. Once you have your kit installed you can begin with the tuning process. Let’s start by using 8psi as your current max boost setting. Before we raise the boost at all, we need to set the turn on point “on set” for the pump. This is done via adjusting the pressure switch or knob on the controller depending on the kit. The switches are adjustable via screw, knob or nut in most cases. How they work is simple. They have a constant power of 12vdc hooked to them, as well as a vacuum line from the intake manifold. Once the manifold pressure reaches a certain pressure, the switch will send that 12vdc to the pump. In order to figure out the “on set” point, other than trial and error, you need a vacuum pump. These can be purchased at any auto parts store.
As you can see, it has a pressure gauge and trigger to increase the pressure output. Apply pressure to the vacuum line of the switch and see what the pressure is when the pump is triggered. Then adjust the switch to the required setting. Well, how do you know when to set to pump to come on? The key here is having it come on as late as possible, but early enough to supply the alcohol when you need it. If the alcohol was injected the moment you hit 8psi then your tuning would be easy. But you have to account for the lag time involved for the pump to “spool” up and fill the lines as well as having the mist actually reach the combustion chambers. So lets start with an “on set” pressure of 6 psi. That should give us enough of a buffer before we suffer from a lean spot or any detonation. Now we have 1 or 2 options depending on what kit you’ve gone with. One kind uses jets to adjust the amount of alcohol injected; the other kind uses a rheostat to control the pump volume itself by limiting the current the pump receives. If you have the kind with jets, then you will start with a medium sized jet. If the motor bogs upon “on set” then you simply need to use smaller jets until the car no longer bogs. Yes this method is crude, but it’s very effective and has been used since the 60’s. If you have the other style controller that is mounted in the cockpit, just adjust the knob controlling the pump speed until the motor doesn’t bog. This step is done while driving the car under stock boost conditions. Once the “on set” and injection volume is set, you can begin to add boost. Under perfect conditions we would use a wide band O2 meter to insure we don’t run into a lean condition by adding to much boost. If you don’t have a wideband, you have to resort to checking your plugs and listening for knock the old fashioned way, I don’t recommend this at all. I use the MSD Knock Alert as well as a wide band O2 meter. With these two items you can really get every last bit of power out of any kit you decide to use. If you’re going to wing it without a wideband, have the onset point come on a few psi early and I don’t recommend adding more then 5 psi until you can confirm your AFRs.
Option 2 is a variation of option 1 except we use two nozzles instead of one and we add on a solenoid valve and pressure switch to control the second nozzle. Its setup almost the same as the single nozzle kit, except now we have a ‘T’ fitting on the pump output. One line goes to the first nozzle, the second goes to the solenoid valve and then to the second nozzle. The second nozzle will need to be adjusted via jet size however. Since the controller can only adjust the pump volume once. Once the second nozzle is installed, all you need to do is repeat the original process but using 4-5 psi more then the initial as the “on set” point. So in our case we would have the solenoid valve open at 12psi. Since there is no lag time for the pump to spool up, the Meth will be at the nozzle almost instantly. Now raise the boost another 5-6 psi and you’ve just made close to, if not more then, 100 horse power. With the 2 stage kit, you’re using Meth as a fuel source as well as an octane booster, so a wideband O2 meter should be considered a must have for tuning, although it has been done with just a knock meter.
Options 1 and 2 are crude when it comes to tuning because the AFR is always rich upon the onset and then it leans out as the boost comes on.
The last option is the best method by far in my personal opinion. It uses a variable controller. With this setup the pump volume is increased as the boost rises. Most kits use a MAP sensor but some tap into the Mass Air Flow sensor (MAF) and use the 0-5v output. With this type of kit, the sky is the limit. The install is roughly the same as the other kits, except you have the controller mounted inside the car. The controller has the option to adjust ALL of the settings while sitting inside the car. Just a few turns of a few knobs and you’re done. Ok, it’s not THAT simple, but its close.
For this kit you perform the same steps to set the “on set” point, then you set the “max boost” setting. Again, just use the hand pump to set the “max boost” setting if the controller doesn’t have a specified PSI reading on it. Some kits have a variable ramp adjustment, which allows you to tailor the actual rise of the pump speed between the “on set” and “max boost” for maximum power, others have a set amount. All variable kits have a max volume adjustment, this enables you to set the max amount of Meth being injected so as not to run super rich, or even lean once the motor is running at max boost. With this type of kit, you can run huge amounts of boost and easily max out your turbo or the internals of the motor.
Now that we understand what’s involved with running alcohol and or water injection, we can discuss the bad things about it, which just so happens to be the easiest part of the article… because there aren’t any. GM was going to use water injection on the Buick Grand National back in the 80’s and ran 100’s of miles of tests with NO adverse affects. You’re going to run into people who will say Methanol is corrosive and dangerous. You look those people in the eye and say, “see you at the finish line” cause you’ll be there having a beer waiting for them. Any kit you buy with the intent on running Methanol will be made from materials proven to work with Methanol. Since Meth is the most corrosive chemical you’d want to inject, it’s safe to say that any other chemical you want to run will work just fine.
When tuning with more then 1 type of fuel, you need a wideband that shows Lambda as well as AFR. Here is a graph that shows a Lambda conversion. Notice that 1 lambda is 14.7 AFR for petrol and 6.4 for alcohol. If we’re looking for a 11:1 AFR under boost, we’re going to want to run a lambda reading of .75. We can use the .75 Lambda to tune for alcohol as well.
Here’s a quick list of chemicals we can find in a lot of common places. From paint supply stores to Home Depot. I recommend Toluene and Methanol do to availability and very high octane rating.
At this point it might be prudent to remind you that the handling of alcohol fuel, even in small quantities, is dangerous since poisonous Methyl Alcohol is the basis for most of these fuels. The effects are cumulative and if enough is allowed to build up, it oxidizes forming Formaldehyde causing blindness and insanity. But I’m fine and so am I…Another point to consider is that alcohol is a solvent and so far as certain paints are concerned it acts as a perfect paint stripper. Alcohol also has a very thorough scouring effect on tanks, pipe lines and so on, not forgetting it can on certain types of fiberglass tanks cause them to disintegrate into a rather nasty sticky mess.
In closing, be careful as you go about adding boost. It’s more addictive then Heroin!!!
Article By:Brian Falla, NICOclub.com techie and Nissan Enthusiast