Last weekend at the gas station, I discovered too late that I had just filled-up my MCS with regular unleaded. Either I was just inattentive or I subconsciously decided to spring for the cheaper gas -- who knows!

Anyway, I paid for my inattention with a week of really lousy engine performance. To play it safe detonation-wise, I deliberately drove at lower RPMs. I almost filled up with super at the half tank point but decided it was better to suffer through 1 tank-full rather than 1-1/2!

I finally got through my ordeal this weekend. With premium fuel in the tank again, the ECU is thankful and I have a renewed appreciation for how much fun this little car is to drive!

 

After about 40 miles you could have added a few gallons of Super High Octane 100+.
I don't think your MINI was too happy. My regular gas is a robust 87 Octane while premium is 92.

 

WHere does one buy 100 octane??

 

>>WHere does one buy 100 octane??
Select Sunoco dealers. Check their website for race gas dealers.

 

How much is that running a gallon?

 

Here in Australia the standard fuel is 93 octane whereas premium is 98. I always use premium btw. Maybe that is why we don't seem to suffer from the stumbles & yo-yo...just a thought...

 

"Here in Australia the standard fuel is 93 octane whereas premium is 98."

Well here it's 87/91.

I wonder if we're using the same octane rating formula in this comparison, though.

 

is gas unleaded in Australia? Dunno if that affects the octane figures...

 

>>Here in Australia the standard fuel is 93 octane whereas premium is 98. I always use premium btw. Maybe that is why we don't seem to suffer from the stumbles & yo-yo...just a thought...

Most any where outside of the US, the octane rating system is different than the US. 98 in Australia doesn't mean the same as 98 in the US. In the US, pump octane is also referred to as the Anti-Knock Index (AKI). AKI is determined based on an average of the Research Octane Number (RON) and the Motor Octane Number (MON). The formula is RON+MON/2 normally abbreviated as R+M/2 on the pump. I believe outside of the US, the octane rating reflects RON and not R+M/2. :smile:


_________________

 

As far as I know, the rating for our fuel is 'RON'. Hope this helps
http://www.choice.com.au/viewarticle...100008&p=1
And yes, we do use unleaded.

 

I love the octane discussions :smile: As has been pointed out in other threads on this topic, your engine is looking for a certain octane around which it can provide optimum performance. The computer adjusts the ignition timing to deal with a range of possible octane, but that range has a lower AND UPPER limit. If you run on less than 92 (or whatever it is in your native land), performance deteriorates since the engine can't compensate for octane that low. But at the same time, if you put in gas that's much higher octane, it's not like your performance will just get better and better. Rather, the computer adjusts ignition to make the performance the same as if you had put in 92. The target, in other words, is what you get when you actually run 92 octane. Putting in 100 octane gas is just a waste of money.

 

Not if you get a selectable ECU mapping to adjust for the higher octane.

 

>>How much is that running a gallon?

My local Alliance carries 100 octane (actually, it's called Trick 101) for ~4.00/gallon. It used to be $3.50 until everyone and their mom found out about it and started pumping there. While I haven't pumped it in the MCS yet, it's the only thing I run my Porsche on in these hot So Cal summer nights.

 

Be careful about octane ratings, there is a point of 'bad' returns. Most of the race fuels you will find at your local gas station runnin the 104 to 108 range, this is way too high for your mini, in fact it's way too high even for a JCW Mini. You should never put more thatn 98 octane in your mini, unless you have a turbo charged 300+hp car. Too high of an octane will burn your engine up!
Interestingly enough my local Sunoco station has 93 octane and its actaully cheaper per gallon than high test (usally 90 to 92octane) from any other station in town (Danbury, CT)

 

>>Not if you get a selectable ECU mapping to adjust for the higher octane. :smile:

 

>>Be careful about octane ratings, there is a point of 'bad' returns. Most of the race fuels you will find at your local gas station runnin the 104 to 108 range, this is way too high for your mini, in fact it's way too high even for a JCW Mini. You should never put more thatn 98 octane in your mini, unless you have a turbo charged 300+hp car. Too high of an octane will burn your engine up!
>>Interestingly enough my local Sunoco station has 93 octane and its actaully cheaper per gallon than high test (usally 90 to 92octane) from any other station in town (Danbury, CT)

Just so we are clear about what octane means........
Octane is a measure of the anti detonation characteristics of the gasoline, in other words, how UNEXPLOSIVE it is under pressure.
the "knock" we hear from engines running on low octane number is the actual crashing of two flame fronts, one started by the spark and the other started by the pressure....they collide and the resulting "bang" turns into a "ping" when it gets to your ear. If violent and repetitive enough, these innocuous pings will tear parts of your piston off its surface and eventually melt it.
In short....120 octane fuel will do nothing harmful to your engine, though it is liable to hurt your wallet. And yes I do work in the industry and yes I know what I am taking about. 120 octane fuel will allow you to time the engine to within an inch of its life (right on kenchan) but it cannot possibly harm it. :smile:

 

>>>>Be careful about octane ratings, there is a point of 'bad' returns. Most of the race fuels you will find at your local gas station runnin the 104 to 108 range, this is way too high for your mini, in fact it's way too high even for a JCW Mini. You should never put more thatn 98 octane in your mini, unless you have a turbo charged 300+hp car. Too high of an octane will burn your engine up!
>>>>Interestingly enough my local Sunoco station has 93 octane and its actaully cheaper per gallon than high test (usally 90 to 92octane) from any other station in town (Danbury, CT)
>>
>>Just so we are clear about what octane means........
>>Octane is a measure of the anti detonation characteristics of the gasoline, in other words, how UNEXPLOSIVE it is under pressure.
>>the "knock" we hear from engines running on low octane number is the actual crashing of two flame fronts, one started by the spark and the other started by the pressure....they collide and the resulting "bang" turns into a "ping" when it gets to your ear. If violent and repetitive enough, these innocuous pings will tear parts of your piston off its surface and eventually melt it.
>>In short....120 octane fuel will do nothing harmful to your engine, though it is liable to hurt your wallet. And yes I do work in the industry and yes I know what I am taking about. 120 octane fuel will allow you to time the engine to within an inch of its life (right on kenchan) but it cannot possibly harm it. :smile:

Is that a green car you drive

 

"In short....120 octane fuel will do nothing harmful to your engine"

I'm glad you clarified this. Having only a casual knowledge of how the octane number relates to detonation, I was having trouble rationalizing MGear's contention but didn't feel confident enough to question it here.

 

>>"In short....120 octane fuel will do nothing harmful to your engine"
>>
>>I'm glad you clarified this. Having only a casual knowledge of how the octane number relates to detonation, I was having trouble rationalizing MGear's contention but didn't feel confident enough to question it here.

I treat my Mini to a few gallons of Unleaded104 Sunoco when ever I ($$$$$$$$$$5.95 per last time) can and boy is my Mini happy :smile:
The less knocking the ECU detects the less it needs to pull back timing.
I know when ever I get a crappy tank full with in a few miles.

 

>>Just so we are clear about what octane means........
>>Octane is a measure of the anti detonation characteristics of the gasoline, in other words, how UNEXPLOSIVE it is under pressure.
>>the "knock" we hear from engines running on low octane number is the actual crashing of two flame fronts, one started by the spark and the other started by the pressure....they collide and the resulting "bang" turns into a "ping" when it gets to your ear. If violent and repetitive enough, these innocuous pings will tear parts of your piston off its surface and eventually melt it.
>>In short....120 octane fuel will do nothing harmful to your engine, though it is liable to hurt your wallet. And yes I do work in the industry and yes I know what I am taking about. 120 octane fuel will allow you to time the engine to within an inch of its life (right on kenchan) but it cannot possibly harm it. :smile:

You are correct in that the higher octane is less susceptible to pre-ignition (pressure). But, the higher the octane, the hotter the gas will burn. This means that parts will eventually begin to melt, especially the catalytic converter. Unless the car is built to run on high octane gas, then there is really no necessity to run that high of an octane gas. Mixing in some higher octane won't hurt, but there is really no need to run higher than 93. Your wallet will thank you.


If you're running great using 93, you will not be running that much better at 104.
If the ecu isn't seeing knock with 93 it won't pull any timing. At nearly $6 a gallon for 104, I'll stick with the 93 for less than $2.

 

Here's a handy link for those in SoCal looking for Sunoco 100+

http://www.cosbyoil.com/racing.htm

 

04yellows,

Actually race fuel runs cooler rather than hotter. If you run race fuel on a low compression engine it can reduce the hp output (result of less heat). It WILL NOT damage the engine. A favorate trick with motorcycles that have chrome pipes is to run race fuel to prevent the blueing of the chrome.

 

Sanddan is on the right track here.

Changing to a higher octane will not increase heat or do damage.
But, doing so allows for an engine tuner to bump up compression and advance timing without the engine knocking. THIS is what creates the excess heat and potential damage, not the fuel itself.

 

Sooooo...what's the verdict then? If 104 won't do any harm, will it do any good for a pullyed Mini with ECU remap like Unichip or powerchip? Will the ECU further lean the mixture to allow more power?

Thanks

 

The calculation for octane is different in the US than almost everywhere else in the world...so the european (and I guess Anstralian) 98 is ezuivalent to about 93-94 US

L