Quote:
Originally Posted by SIVIirnoff
I have a quick question that I want to answer before I jump into the world of alcohol injection. I am trying to figure out the best balance between getting the benefits of alcohol injection and reducing the inconvenience of trying to find/store/handle methanol. My reason for getting this setup would be to reduce detonation to protect my engine... performance gains is just a bonus.
-What kind of detonation resistance would I see with using only water?
-Would the benefits of using only water outweigh the cost and hassle of the water injection kit?
-What, if any, performance gains could I expect with using only water?
-With regards to meth, how much of a hassle is it to find/store/handle? any suggestions in this department?
This setup will be on a 2011 Subaru STi which experience has shown us that these engines are very susceptible to detonation and when detonation is present in these engines, bad things happen.
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Its very well documented in older papers listed freely on this site and also on mine under the WI section. I am in the midst of writing my own paper on this and reworking it for a more layman audience and in modern understandable units of measure.
In very quick summary though
YES to all your questions, water is worth it, and it will cure all detonation problems while also giving you more power with less stress on the engine than ANY fuel you care to imagine.
You need to for normal air temperatures between 70 to 40 deg C run anything from 20% to 60% water to base fuel by mass to allow you to have very large power gains *through increased boost pressure in the main* (along with total elimination of any engine knock). These ratio's of water to base fuel are for big results, some people use lower ratio's like 10% or 15% by mass to achieve smaller gains in power, in some set ups that may be all you need to cover the amount of boost you want to run or have a very big knock safety margin for all conditions.
Water injection is the single best thing you can do to any engine, especially when it is running high air inlet temperature (+40deg C) when artificially pressurized. The maximum amount of methanol to mix with water is 50% by mass, any more than this makes the mixture more knock prone. The mixing of methanol in with water can allow ignition limited set up or boost fixed set ups to have a low loss in power with very high increase in knock resistance. The more water you can run is always better, but each set up is slightly different as are peoples situations too, so its a case by case thing.