427C62013A

Here from MIT:

Direct Fuel Injection (DI) extends engine knock limits compared to Port Fuel
Injection (PFI) by utilizing the in-cylinder charge cooling effect due to fuel
evaporation. The use of gasoline/ethanol blends in DI is therefore especially
advantageous due to the high heat of vaporization of ethanol. Additionally
ethanol blends also display superior chemical resistance to auto-ignition,
therefore allowing the further extension of knock limits.

Source:
https://dspace.mit.edu/bitstream/han...670245-MIT.pdf

Jimbob26

I filled my Corvette up last week, and while I ordinarily put Premium (in CA it's 91 octane) in the car, one service station I sometimes use has the fuel types backwards from all the others, so I accidentally put in Regular (87 octane) in it. This is the second time it's happened, but like last time when the tank gets to 50% I'll top it off with Premium. I always use Chevron gasoline ( I used to work for Chevron and my wife still does), so I am a bit biased.

fnbrowning

In Missouri, the Department of Agriculture is responsible for Fuel Quality Testing. A few years prior, I had a question about a Phillips 66 gas station in Florissant, MO, and I contacted the Department of Agriculture about the inspections at that Phillips 66. The representative was polite, knowledgeable, and helpful. In Missouri at least, I am satisfied that the Department of Agriculture takes fuel quality testing seriously and does a credible job.