Wednesday, June 25, 2008

How much ethanol is REALLY in my tank

The seasonal variability in ethanol content of E85 makes determining what the hell is really in the tank very difficult.

I too a closer look at this document, and I see that it only specifies MINIMUM ethanol content by month. The MAXIMUM content is ALWAYS 83% (so the 85 in E85 is BOGUS).

So I did the graph to figure out what is the most ethanol that could be in the tank, and what the least amount could be. I'm somewhere in between.

Interestingly, it appears that I am now above the ethanol content that gave me a CEL on tank #4. I'm still below the amount that gave me the first CEL.


Anonymous said...

You noticed that the Feds book is one of the most upsidedown documents ever created eh? I studied this for a long time looking at both the ethanol content chart line and then the hydrocarbon line and decided at that point to call the head of the NEVC to confirm what the blends should be before I ever set up the first dispenser. Reading the document makes you wonder if every place you buy from has it right doesnt it? "we are from the govt and we are here to help you" LOL !
Blend should be in terms of pure alcohol (not including denaturant)-- 70% winter, approx 77% spring/fall and 83% summer (max).


buzzcut said...

Yes, I found it very confusing.

There is no requirement to decrease ethanol content by season. So why would anyone do it, considering that ethanol is so much cheaper than gas?

Anonymous said...

I decrease it because while even though the "book" is almost wriiten as a loophole there is no way that was the intent of either the DOE or automakers to have such a low vapor pressure in the winter as summer grade E85 would yield. I want people to be satisfied and their vehicles to start everyday regardless of if it is -30 or not.
Right is right- wrong is wrong. Some states are starting to include E85 in their quality inspections and hopefully will eliminate poor behavior by dishonest retailers. If retailers play games they will kill confidence in this product. From a car operating standpoint- it does not matter so much if the retailer is one month ahead or behind of the class for the season but summer E85 is too low of vapor pressure for good starting in winter and winter E70 is potentially air polluting with high vapor pressure in the summer. Plus Winter E70 will be too likely to vapor lock a low pressure carbed race engine for the guys who use it at the track.