Why is it that we always hear about jap petrol which has an higher ron 100+,thought petrol was petrol

I know you get higher ron-super,v power etc. But they still not 100+ ron so why cant we have jap petrol in this country, whats the difference?

 

I don't know the reasoning behind different countries having different ratings (emissions/pollution perhaps) but it is higher in Japan, as is V-power on the contintent, thats 100 Ron as opposed to 99 over here.

 

Um, they just have different grades available like just about everywhere else in the world, they did get 100 ron to replace hi-octane leaded when it was fazed out where as we only got 98.
I kinda found it amusing if you look on the japanese forums, they seem to keep moaning about having to buy hi-octane unleaded for there european imports because they wont run / det on regular grade.
Also if you translate the subaru brochures they just state premium unleaded (hi-octane) fuel, with a side note that lower grade maybe used although power output will be reduced.

 

would like to see some scientific proof that hi-octane fuel is needed more scoobys

Apart from losing a few bhp what experience have people had with the two?

 

I suppose it depends on your ECU's ability to alter the timing in relation to higher or lower octane, there must be some limit to the amount of advance/retardation of timing that can be applied to allow for different octane fuels.

If an engine is set to run a higher octane fuel then perhaps, a much lower octane rating would be outside of the running parameters, and so det will set it?

Ask a tuner though, is your best bet.

 

explain det to me

 

This is how i understand it, but i only know very basic mechanics (often referred to as dangerous, i little knowledge that is )

There is a set point at which the mixture is supposed to burn, (i'd think at the end of its travel) so when its ignited it pushes the piston back.

Lower octane fuels can detonate/pre-ignite as the piston is compressing the air/fuel muxture, before it reaches the optimum burning point in the piston travel.
This detonation (instead of the energy pushing the piston back out, as it would if it occured at the right moment in the cycle) then shocks the system putting strain on the components in the system (pistons, bearings), as the energy has to dissapate somewhere, but its still on its compression stroke.

As i said thats very basic and may not be entirely correct.

 

can use 95 RON for daily runs to and from work and stick in 99 RON when going for a run.

lets face it. Most of the time (Mon-Fri) we only use it for work so don't need 99 RON

 

How long does it take for the ECU to 'learn' a different batch of fuel though?

 

very good point dill.

as many others have said on here, why buy a performcane car if you cant/wont/dont want to put decent fuel in it. ie v-power/tesco 99 etc.

beggers belief. i pootle about most the time, but still use v-power regardless.

andy