Hi Guys, here is some easy to read info on octane ratings for all.
OK , Octane is a fuels resistance to 'knock' .The higher the number the greater the resistance. Knock is very undesirable as it is the point where the fuel is no longer burning
in one controlled direction (moving from the plug) but self igniting causing two flame fronts to collide.
Octane can be measured in 2 ways ,both using very slow speed single cylinder engines. MON tests at WOT, whereas RON tests at half throttle. Because of this ,logic
suggests that a good MON figure is more important to us than the RON figure,as you
dont race on half throttle!
In the UK and Europe our fuel at the pumps is rated as a RON figure. As a general rule the RON figure is about 8 higher than the MON . Therefore 98 RON 'Optimax' is around 90 MON.
In the US they use 'AKI' which is the average of the RON and the MON . Therefore what we
call 98 they call 94.
AFAIK the highest octane unleaded race fuel possible is circa 106 RON / 98 MON.
With leaded fuels the RON can go to almost 130 ! . If you run leaded you will murder the
cat and the lambda sensors tooso dont do it.
So why bother with high octane if the timing can be retarded to prevent knock?
OK, the 3 variables which can be increased if we utilize more octane are;- compression,
boost pressure,ignition advance,or any combination of these. Assuming everything else is ok,all 3 will increase power.
Im sure there's loads more I've missed but my brain is now a total void.
Regards Roland Gt Tuning