The owners manual says use 91 octane but the dealer (and everything else I've absorbed over these many months) said 93 octane for the S. Driving through the frozen tundra, I was usually only able to get 91 (92 on the rare occasion) so I ran at least 2 tank fulls of 91 and put some octane boost in (eww )

In Seattle, 92 seems the norm and I don't have any easy access to airplane fuel. Can anyone comment on the REAL difference between 92/93 and what additives might be worthwhile. I want the S on the proper diet.

Thanks in advance.

R

 

There seems to be some debate about which type of numbers are being used - or recomended; the European 93 is like our 91 ... I used to know the difference but the chemistry escapes me now ...
... I, too am in Seattle and the 91 is good for our cars - since they all come from the same barrel in Anacortes, feel safe about using any major brand.

 

Those bottles of octane booster really do nothing. When it says it increases your octane by 4 points, that means 0.4 so your 91 goes to 91.4.

These boosters are either toluene or xylene, or a combination of the two.

In the past I have formulated my own race gas using premium and a combination of these molecules, but I no longer have a chemistry lab to do it in.

But there are some excellent home-brew recipes out there that I will take no responsibility for telling you about if you blow yourself up.

 

91 will be fine.

 

I've had 100 octane in mine and didn't notice a difference. It
was over a 48 hour period so perhaps the ECU didn't adjust???

 

2Minis,

Did you get that from the guy on 118th? I was thinking of trying a mix of 1/8 tank to see if anything happenned.

no difference eh ?

 

No. Up at Roebling Road...

 

Your car has a knock sensor, and has been designed to use whatever grade is available. You won't harm your engine.

Plus, 93 in Europe does not equte to 93 in the US. I believe they use the RON value, and we typically use (RON+MON)/2. 93 in Europe equates to about 91 in the US, if memory serves. Someone feel free to correct me if I'm wrong.

At any rate, don't lose sleep over it. Unless you are drag racing or doing dyno runs, you'll probably never notice the difference between a couple of octane points.

 

2minis.

If your engine requires 91 Octane and you put 100 Octane in you will not notice a difference.

The higher the octane the harder you can compress it before it combusts on it's own. (knocks .. BAD!). That's why it doesn't matter if you put a higher octane in than required.

In our forced induction engines the pressure is higher compared to a naturally asperated one. That's why we need a higher Octane. It's the fact that we can run the engines at a higher pressure that gives us more power. Not because we use more 'explosive' fuel.
:smile:

 

I would have gotten regular high test but I was locked into
the track and that was the lowest octane they had.
Another question though.....
I have heard...can't remember where...higher octane =s lower engine temp???
Comments?

 

The 'S' with low compression and boost, and the hi-compression Cooper both require the same premium octane fuel. ... and octane actually slows the progression of the flame front moving through the combustion chamber so it's less 'explosive' ... and therefore maybe 'cooler'

 

>>I would have gotten regular high test but I was locked into
>>the track and that was the lowest octane they had.
>>Another question though.....
>>I have heard...can't remember where...higher octane =s lower engine temp???
>>Comments?

That makes sense. 100 Octane would stop knock even when your accelerating as hard as you can.

 

Octane rating is also a regional rating. Here in Dever the highest rating of most premium fuel is 91. I believe tha altitude affects the rating number. It is supposed to be the same as a 93 at lower levels.

 

A note of caution to anyone toying with the notion of using aviation fuel to capture higher octaine. Avgas is one of the few fuels that still contains lead.

In addition to being an environmental terrorist, you will make your MINI sick. You also risk being issued one of those nifty orange jumpsuits to go with your new 6 x 8' living quarters.