Gas-octane rating 85,87,91-does it matter?

[Momo]

IMHO premium gas is an absolute waste of money in a Series Rover.

Generally Jim I am with you on this, but once the compression ratio goes up, higher octane can be necessary. One of my Rovers will ping with anything less than 91 octane fuel. Kinda sucks, actually.

[knac1234]

Looks like I shall just experiment a bit with the fuel. Thanks for all the tips! No non-ethanol fuels near me in Colorado unfortunately....I am in Divide.....45 min west of Co Springs.

Cheers,
Julian

[Apis Mellifera]

I've heard reference to ''pinging'' before ,have never experienced it and not sure I would know it if I did. Can someone explain the sound?

http://www.youtube.com/watch?v=Due7mkTHMlw

Sounds like an uneven rattle when under load. Kind of like the sound of a small hammer pecking on an anvil. You can hear it around the 3 second mark in the above video.

Compression and ignition advance are the major factors relating to detonation (pinking/pinging), but other things can cause it. I consider anything over the lowest octane available to be unnecessary in my Series III (8:1 and a little advanced). I have an MGA with a mild race engine (9.8:1) and it requires 93. I could probably get by on less, but I generally run a little more advance on that engine than that of a street car. That said, detonation isn't good and you should use whatever octane you need to prevent it.