Quote:
Originally Posted by night9
Thats pretty interesting results. I was looking into why this would happen/make a difference in mpg. I came across an interesting thought that the ethanol in our fuel was causing a need for lower temp spark plugs to prevent detination. I don't know if that is the cause but I am interested in maybe trying this out at some point. I can only find E10 gas here.
|
I thought the presence of ethanol increased the octane, not lowered it. I understand you can jack the compression on an engine that only ever runs E85 up to crazy high levels with no risk of detonation. I don't know what the ignition thresholds are like for ethanol but I reckon if it's harder to ping, it's probably a little harder to light, too. I'm just taking a flyer here, but I would think ethanol would benefit from a hotter plug, not colder.
OP is taking advantage of his computer's programming to maximize economy with a colder plug, which permits more advance and therefore a more complete burn.