in say an E85 blend, how long will it last once it is open to the atmosphere before it has an effect on the fuel
The length of time depends on many variables but mainly temperature and humidity.
The easiest way to know if your fuel has been seriously effected by atmospheric moisture is to look for phase separation. To do this you will need to shake the fuel vigorously and inspect a sample. If the fuel appears milky then you will have phase separation. I will do an example today or tomorrow and upload some images so that you know what it looks like.
This test is obviously harder to do when the fuel is in the tank as it is hard to shake a car vigorously. In this instance the best method is to take a sample from the top of the fuel cell and then one from the bottom. Provided that petroleum soluble dies have been used phase separation will be easily identified if the two samples are different colours. If you are unsure by this method mix the two samples, shake them and look for the milky appearance.
If you want to determine your fuel quality we will soon be selling Spec Chec alcohol fuel test kits, these will enable you to quickly test various aspects of your fuel.
We use a very dry ethanol in our blends, this is generally tolerant to 20% water in an E85 blend. As far as time storage goes we rate the fuels as having a 6 month shelf life if stored correctly, this is not so much due to the hygroscopic properties of the ethanol but more so the gum formation in the petroleum component.
also will sitting in an alloy in car tank, which has a breather open to the atmosphere for a month between events casue any issues over time?
We don't recommend long term storage in fuel tanks, but having said that we don't drain our tanks and have never had a phase separation problem, even after several months of storage. With regard to the tank being alloy Alcotane fuels have a pHe stabilizing additive that inhibits the corrosive properties of ethanol when in contact with aluminum.
can you provide a bit of info what Ethanol percentage requies some fuel system changes - ie I know E85 pretty much requires specific fuel line and associated changes, with a fuel system flush recommended after each event, especially for carbs.
We have had several people tune their cars to our E30 but as E50 is a new product I don't have any "real world" results for it. With E30 you are typically looking at up to a 10% increase in fuel system demand, your fuel lines will need to be ethanol rated (this is the case with all ethanol blends)
As far as flushing the system goes, I personally believe it's a waste of time with Alcotane products due to the effectiveness of the additive. As long as you are running ethanol rated fuel lines then you should be fine. We have never flushed our systems and have had no problems.
As an indication E30 is suitable for static compression ratios up to 12:1, E50 for up to 14:1 and E85 for up to 16:1. This is largely a guideline and can vary greatly depending on your specific application.