I just got thru reading reading the 71 owner's manual for the 1200 Coupe (North America) just for grins. It states to use 90 octane gas. I been using 87 all these years. Is 87 OK or do I need to go the premium route? Car seems to run fine. Thanks.

87 is fine because they changed the rating method. Now they use R+M/2, which is about what 90 used to be.

Hey how do you get the octane number of fuel and what does RON stand for when talking about octane.
Thanks heaps

Damo

our premium unleadeds are pretty much all 98+ octane

unleadeds are bout 95

super not sure bout 95 i think

but im guessing ours and US are measured diffrent cause cars would struggle to run on 90 octane in our measurement, and their cars are rated with higer powers like japans are because they have better fuel

u know how we get detuned integras and wrxs and s15's ect ect because we have crappy fuel

There are two different octane ratings: RON and MON. RON is the Research Octane Number, it is the fuels ability resist detonation during acceleration. MON is the Motor Octane Number and it is the fuels propensity to knock at high engine speeds.

The "R+M/2" is the RON + the MON divded by two, used in some parts of the world instead of one of them.

How do you measure octane rating? A special machine called a "variable compression ratio test engine" is used. Anyone have a clue how this works? I am interested.

Hope this helps

Simon

Quote:This is a one-cylinder engine in a test stand. The head (IIRC) can be moved up/down over the cylinder to vary compression. Thus they can measure at what point a particular fuel starts to knock. The comrehensive initial research on octane was done in the 30s (?), but a similar test engine is still used today. For more information, search the web for "tetraethyl lead".

Thanks for the informative note. This is quite an interesting board and I always learn something new about my old rust bucket of a car. Thanks. 87 octane it is.

i'm over in perth and my dat loves the 98 fuel runs better has better response and keeps everything in there cleaner. better fuel econemy too

Dont know about octane rating over there but i can tell you that it doesnt mean "jackshit" over here.......

I have even heard examples of random tests on so called premium unleaded fuel from the pump, with a lower octane rating then standard unleaded. My Sugestion is that if you are going racing, buy drum fuel such as ELF etc etc...........

Cheers
Peddler

Has anyone else had success with the premium unleadeds? Personally I haven't found any difference in the way the car runs or the fuel economy.
Matty