Postby JMlegacy » October 20th, 2016, 1:09 pm
So after designing, making and running a methanol injection system (50/50) on my car for some time now I think I can share some of my findings.
A progressive system is the only way to go for maximum power and drive ability. And I don't mean progressive pump pressure, but progressive pulsing to solenoids. Aquamist is a good brand if you can't engineer one yourself. Stay away from progressive pump speed.
Secondly,a fail-safe is so important. I have a fail-safe that tells me when the pressure in the water line falls below x psi, and disables the boost until that is sorted out. I noticed a lot of time it shows low pressure makes me wonder if my hose has a leak, but what happens is that this system has a way of getting air into the pump head, which causes the pump to not pump at full pressure. Whenever this happens I bleed the system - place the output hose into a bottle and let it run for a while. You will know when air is present in the system if the pump gets quieter than you normally hear it.
I also have a low fluid level sensor which does the same thing – pulls boost when that happens.
Thirdly, atomization becomes more important the higher the water ratio you use. You need the fluid to vaporize as much as possible before it enters the combustion chamber, this evaporation removes heat so the more heat you remove the more power you get. Also, higher water ratios love higher boost. Yes, the increased pressure makes it harder to evaporate in the intake but the increased heat compensates for that. More about this later.
Tuning this WMI is where it gets debatable. I choose to run high timing and moderate AFR (11.3). That has allowed me to see 26% increase in power. The more water you use the less timing and leaner you may end up. I choose the more timing less fuel as the ECU can pull timing but cannot add fuel. From time to time your meth system WILL have hiccups. Believe me, i've been there. No matter what you do it WILL have hiccups, whether it is a partially clogged nozzle (yes i have a filter on both nozzle n pump) or air in the pump head, it will have have hiccups. Mine does this about once a month, and I'm one that monitors my knocks almost every race event or any extended pull. My 11.3 actual AFR comes from a requested 11.75 AFR in the ecu. IF my system fails for whatever reason that is the AFR i will end up at. What if it were 12.5? Is 10 more hp worth that? OK.
Both high timing and lean AFR leads to higher cylinder pressures. Some say higher timing comes with the risk of loading the rods more on the compression stroke than do leaner AFR, which is true, but on the power stroke though, that's where all the stress is. Which leads me to another tip: avoid high timing in the midrange just to get that boasty torque figure! Torque is directly related to mean cylinder pressures. High pressure = rod stress! Always use boost as the bigger volume knob, timing and then AFR.
Water / meth ratio is another area of debate. Some believe in running 100% meth and others love water. But let’s look at this for a minute. If you run pure water you will have a longer living pump, you will have to run leaner afr and you will making less power than those with alcohol. I'm not too excited about leaner AFR for reasons mentioned before but I welcome the longer pump life. Water also requires lots of heat (timing, afr, boost) to work well.
Water also has an incredible effect on torque: water expands to 1500 times in volume when converted to steam! This steam expansion turns into torque. This is another area where water injection makes power.
Now, using alcohol is commonly attributed to an increase in octane. I’ve found this to be too much of a great generalization. Alcohol does one thing well – it cools the induction way better than water. In the combustion chamber the alcohol also removes some heat, but water does that job better. You will need a much larger nozzle for the 100% alcohol to do the same work that water does in the combustion chamber. There is also another benefit. Alcohol mixing with the incoming air gives a better fuel atomization that leads to a more complete burn.
The best setup is 50/50 which cools in induction and cools the chamber, and a good steam pumping effect.
