Has anyone compared times running current pump gas (at least around here, and I’d imagine most other places the MTBE is gone and has been mostly replaced by a new mixture with somewhere around 10% ethanol), with the stuff from about a year ago?

In theory at least, using ethanol as an additive instead should result in a lower total energy content (need more gas to produce the same power), slower burning (need more timing advance) and a few other not so favorable changes in the combustion chamber. OTOH, if when adjusted for this I’m not sure if one will go faster then the other.

It used to also be that if your engine was not detonation limited on 87 octane the car would run faster on 87 then on 92 or 93 because it had a slightly higher energy content and specific gravity, but some of the numbers that I’ve seen recently are starting to hint that things are swinging the other way.

Anyone experiment with this at the dragstrip/notice changes in the last 6 mo to a year?