petrol

[andrewrx7]

This is pretty much spot on, although the stock ECU is very limited with what it can do with regards to "detecting" detonation.  The only thing that can detect det is a knock sensor.

Higher octane fuel provides less energy when burnt than a lower octane fuel. The ONLY reason your car may feel faster with higer octane fuel is beause the car runs a better ignition map. Lower octane fuel burns faster, so provides more energy. It also provides detonation however.

Hydrocarbon composition has nothing to do with the energy released by fuel, RON is a rating of how explosive the fuel is, period.

If your interested, this is measured by burning a given fuel in an engine with constant RPM, ignition timing etc and measuring the knock level.  They then blend another fuel of iso-octane (100 RON rating) and heptane (0 RON) and when they reach the same amount of knocking in the given conditions, the percentage of iso-octane to heptane gives the octane rating of the fuel.

Interesting! - thanks for the corrections. Its always good to learn something new! :chat

[Bobfish]

google is your best friend mate

[nikp]

Is that right? As I thought you could have over 100 RON rated fuel? For instance formula one, and over in Japan they use up to and including 102 RON - how can 102 be a percentage of one tpye of fuel and another!?

[Bobfish]

you can, mesurements nowadays are done by computers based on a mathmatic equation which can swing one way or the other, i.e over 100 ron.

[nikp]

I know my mathematics! Yeah, you can have over 100% of something: 120mph is 120% of 100mph. But when you\'re talking a ratio of one thing to another, you can never have over 100%! I\'m confused...

[andrewrx7]

I may be wrong, but the RON number isn\'t a %. Not exactly sure how to calculate it, but as Bobfish says above, if you really wish to know, have a search on google, and be swamped under a ton of maths etcs!!

You can get well over 100 RON fuel - I\'ve got 109 sat in the garage for when I had a go on the drag strip (diluted in Optimax to give 100).

[Bobfish]

you guys are misunderstanding...im not saying the highest RON fuel is 100, im saying that they use a liquid with a 100 RON rating as a benchmark.  This will then give you a mathmatic equation you can use to work any RON rating out.

[andrewrx7]

you guys are misunderstanding...im not saying the highest RON fuel is 100, im saying that they use a liquid with a 100 RON rating as a benchmark.  This will then give you a mathmatic equation you can use to work any RON rating out.

No misunderstanding here! Like i said, got 109 sat in the garage at the moment!  (Just need next year to arrive to use the rest of it up!   )

[Bobfish]

that was aimed at the people saying "how do you measure higher than 100 if the measurement fuel is 100 ron"