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Old 06-24-2009, 08:20 PM   #1
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Default Issues with Methanol Injection

Sometimes injecting a blend of water and methanol can have a drastic effect on dropping your intake air temps (IATs). The methanol will "boil" when it comes in contact with the hot air charge from a turbo or blower and that action will pull a ton of heat out of the air charge. This is why it’s sometimes referred to as chemical intercooling. The added benefit of using methanol is that it has a very high octane that can also contribute to reducing detonation. Many people can run high boost without an intercooler because of the combination of these properties.
Windshield washer fluid
There have been a number of myths on using windshield washer fluid for its methanol content. I believe this comes from the fact that many users will fill their windshield washer fluid tank with methanol and water to be injected into the engine. Many windshield washer fluids do not contain ANY meth, so be very sure that what you are buying has at least 30% methanol and no ethylene glycol. I believe there are a couple brands that can be used in this application, but most people will be better off buying drums of 100% methanol and mixing it with pure water (distilled, deionized, RO, etc, but NOT tap water!!!)
Spark Plugs
NEVER use platinum spark plugs when using methanol as a fuel. Hot platinum is a catalyst for the conversion of methanol into formaldehyde, and sometimes this reaction will generate enough heat to combust. This will cause preignition (BAD!!) where the charge is lit off before the spark plug fires.
Potential Issues
Many engines have been burned up when using methanol and it is sometimes given a bad reputation. One problem is that the hoses can burst, and pumps can fail. Now the tune becomes much too hot for the high IATs and lack of octane. There is a way to tune so that the IAT sensor will see the meth and pull timing if there is no meth present. Every methanol install should be tuned this way, although it is sometimes tricky to move the IAT sensor to the proper position and some customers do not want to deal with this issue. Sometimes the air charge may still be so hot when the meth stops flowing that even a drastic reduction in timing will not be enough to fend off detonation and destruction is still possible.

The main issue that I have with meth injection, especially the larger shots, is proper distribution. Back in the carb days the manifolds were designed to flow fuel AND air. Most manifolds now days are designed to flow only air, and having radical loops and bends to increase the runners is a viable option because there is no worry about flowing fuel and causing puddles in the bends and low points. When users use a large jet for the methanol they should inject it as far from the manifold as possible to all extra time for proper distribution. Even better is to use multiple small jets instead of one large jet. Even then there have been more than a couple engines that burned a piston or 2 while everything else looked great. This is because even if the meth has vaporized, some can still coalesce on the walls of the intake and create non-homogeneous distributions.

There is also an issue when trying to spray methanol through an air to water intercooler such as those found on positive displacement blowers (screw and roots). The methanol will coalesce on the high surface area of the IC and re-liquefy. Liquid methanol is BAD! You wound get much, or any, cooling when it is still in the liquid form. Because of this issue there is really no reason to ever waste your time and money on trying to increase the efficiency of your air to water IC by using meth. There have been reports of meth injection working on PD blower applications when the meth is injected on the bottom of the IC. There are potential distribution issues with this plan due to the very short distance to the intake valves from this location.
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Old 05-27-2010, 03:34 PM   #2
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Some more info i wrote in another thread about using meth to raise the octane from 87 to 93.

Methanol has an octane rating at about 119 and a stoich point of 6.4:1. so if you want to make 10 gallons of 87 octane into 93 octane you would need ((10*87)+(x*119))/(10+x)=93, where x = gallons of methanol. So you would need about 2.32 gallons of meth for each tank. You will also have to adjust the fueling due to the stoich point. Lets figure out the % of each. 10gal/ 12.32total gal = 81% 87 octane. 2.32 gal/ 12.32= 19% methanol. Lets calculate the new AFR (0.81*14.64)+(0.19*6.4) = 13.07 as the stoich point. To run a lambda of .784 (~11.5:1 gasoline afr) you would now need to see 0.784*13.07= 10.25 on the WO2 at WOT. (I think that's all right, but you can double check my math)

WTF does all this mean?? Basically you would need to inject at least 20% of the total fuel needed at wot as methanol. That is a huge percentage!! Now imagine trying to flow 20% of your fuel thru an intake designed to flow only air, while trying to maintain perfect distribution to all cylinders. How many jets are you going to use? 1 jet would spray raw meth at the wall of the intake unless you had some crazy high psi injection pump. Meth needs to be in a vapor form to travel thru the intake. If not, it can pool in the troughs and then BOOM, holes in the intake manifold. Defiantly not something i would ever want to try.
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