Austarion

I have a laser that uses normal unleaded fuel as it has the little divice in the fuel line that puts the lead back in the line etc no probs, or its a bottle of additive...
what is it about the starion engines that or any of the older engines that makes them need the higher octane in the fuel just to run right ??

That additive is to replace the lubrication of the head which would have previously been done by the lead then increasing the octane level. And also those additives don't have lead in them, they just have a substitute that works similar to the lead for lubrication.

The starions require a higher octane fuel for a completely different reason. This is due to the combustion pressures requiring a higher octane fuel to prevent detonation. Detonation is essentially ignition of the fuel before the spark plug which can lead to damaged piston rings and bearings and worst case scenario stuffed engine.

Fuel will auto ignite prematurely if there is too a high a compression for the octane of the fuel injected. The high compression in the starion is not due a too high a compression ratio but due to higher pressures created when the turbo forces in higher additional air and then compressing this already compressed air leading to very high pressures in the combustion chamber.

The lower octane fuel will self ignite under compression at lower pressures and temperatures than the higher octane fuel.

I could go into even more detail with flame front speeds and why pre-ignition is really bad but that would probably confuse you even more before you understand the basic principles

haha no no, it would take quite a bit to confuse me about these things, I find them quite interesting and if i can understand them i can work on improoving them. as i was reading i was thinking it the higher octane would detonate b4 the lower but it made sence in the end.. did all this in chemistry lol.
That was a good explanation, simply to the point and said everything to get the understanding.

paradox wrote:I have a laser that uses normal unleaded fuel as it has the little divice in the fuel line that puts the lead back in the line etc no probs, or its a bottle of additive...

Sounds like a drip feed upper cylinder lubrication device to me .I had a Moreys UCL fitted to my LPG one tonner work utes being that LPG is a dry fuel and the UCL was to help the valves live longer & prevent valve seat resession