octane number

[hemon]

Hello everybody,
here is the real owner of this Ultima can am with supercharger.Excuse me for my language because my girlfrien isn’t here to translate....
First i want to thank all of you for your answers. It’s very kind of you to try to help me.
I still thinking about my problem and i don’t find the sure answer...
I have again a question and i hope you all could answer to it : do you know the octane number of the un leaded gasoline in UK and in USA (RON & MON) ?
In France, we have a gasoline called SP95 and SP98. The octane number of the one is in fact 87 and of the second one is 88.
Thank you for answers
Fab

[davefiddes]

In the UK we have standard unleaded which is 95 octane, super unleaded which is 97 octane and Shell sell Optimax which is 98 I believe. We use RON along with the rest of Europe.

Ther Americans use a different scheme as you point out. I've found a useful conversion table: www.btinternet.com/~madmole/Reference/RONMONPON.html

American Speed recommended 92 octane gas for my engine. By running standard unleaded, 95 RON, I am running close to the limits that they recommmend. This hasn't caused me any problems so far on road, track or on a chassis dyno - but this is with a mild 456 bhp and 9.6:1 compression ratio and unlikely to be a problem. Stig ran Optimax (98 RON) with his supercharged American Speed engine I believe to avoid any possibility of pre-ignition.

[builder]

hemon said:

do you know the octane number of the un leaded gasoline in UK and in USA (RON & MON) ?

In the USA, most gas stations have three grades, 87, 89, and 91 (some 92). We use RON+MON average. In most cities, you can find at least one station that has 100 or even 110 at the pump.