Japan has the best gas -- revisited

**splerdu** · January 12th, 2003 07:37 PM

I thought it might be a good time to reopen the argument of EU vs US vs JPN fuel after coming across this thread: http://www.gtr.co.uk/forum/upload/sh...p;pagenumber=1.

The closing arguments to the previous discussion was that since the US used RON+MON, their 95 octane gas is actually a higher octane than the JPN 100 octane, with EU and JPN having less sulfur content in their fuels. The thread, however brought to light that JPN 100 octane pump gas has to be 99.4 to 100.3MON before it can be advertised as such. This would mean that JPN 100 octane, or "hi-oku" as they call it will be about 110 octane by US ratings.

This information was posted by the user "Mycroft" after he emailed the JIS and certain tuners in Japan, his post is as quoted:

The 100oct fuel in Japan is 99.4 to 100.3 MON to be called 100oct it has a CV 4.9% lower than our fuel, to better suit local conditions
The overall effect providing some little change are made to the Spark Plugs, you can run 1 grade cooler (but that is borderline) or open the gap slightly, this is the reason why I found my TT ran better with the 0.9mm gap rather than the 0.8mm as they are in Japan.

With those mods on a standard car we are 'down' less than 1% on the Japanese figures, with more mods the gap increases, at a guess 20hp perhaps on figures around 500hp, but that is just a guess, so treat it with some caution.

Link: http://www.gtr.co.uk/forum/upload/sh...p;pagenumber=1
Link: http://www.jisc.co.jp

Edit: didn't know there was no link tag...