Well, yes, the motos are running 10 to 12 or even 14 to 1 or so. However, I doubt that those same motos are running a supercharger when they are running 10 to 12 or even 14 to 1 or so. If they are running a supercharger, then they are definitely running unleaded racing gas with an octane rating (by the Anti Knock Index (R+M/2) protocol) that is north of 100.

 

I have the works package. It says it in my gas filler cap. Thought it said 93, where do you buy premium 91 octane??? All the premiums I have purchased are 93.

I'll check my manual and the gas filler tommorrow.


Paul

 

Ahhh. If you are blessed to live in California, the highest octane rating for premium that you can buy at most service stations is 91. It is just so enjoyable to be limited to 91 octane pisswater. Those few souls fortunate enough to have a station nearby that sells the 100 octane racing unleaded blend the 100 octane with the pisswater to get to around 93-94. Those who don't (have a nearby station that sells the 100 octane) have to suck it up and suffer.

 

That's funny...I live in PA and I can't get 91....only 87, 89, 93, 94. And a Top Tier Station is virtually unheard of around here. Go figure.

 

Its a gas

 

This is probably a bit oversimplified, but here's my understanding:

Gasoline octane ratings are measures of octane content. They are reported as an index (AKI - Anti-knock Index) and are indicative of how resistant the gasoline is to detonation. A higher octane rating will therefore allow for higher compression ratios and more power. The MCS has a relatively low
static compression ratio to accomodate the increase in compression ratio as the supercharger produces boost. With high boost, the higher octane gasoline will be less likely to knock (detonation). When the knock sensor tells the ECU that there is knock, the ECU responds by retarding the timing which stops the knock and protects the engine. This also reduces power output. That's why I want higher octane gas - less knock, more available power. So it's not that higher octance makes more power. It's that lower octane makes less power available because the timing gets retarded earlier and more often.

IMO if you're not going to rev the car enough to produce boost lower octane gas shouild be fine. If you want all the power the MCS can produce, you need higher octane gas (93 AKI). The same is probably true for the MC.

As to top-tier gasolines, that is more focused on the quality of the detergent package in the fuel.

 

this is some funny stuff 6 pages of what kind of gas to put in a car lol

 

You are right

 

Who is jumping Jack Flash?


Paul

 

CAMINIFAN,

Diesel fuels do differ but based on my seat of the pants dyno I've not been able to tell the difference from my diesel car's performance. I don't run any fuel additives but I do buy from fuel stations (usually truck stops that cater to diesel cars/pickup trucks/RVs) that obviously move lots of diesel fuel so the fuel's fresh and up to date regarding its ability to resist gelling in cold weather.

With my gasoline powered car, I have noticed a difference between brands of gasoline. In fact, with at least one of the cheaper brands, the CEL comes on -- triggered by a going bad #2 O2 sensor (which is used by the engine controller to monitor the peformance of the catalytic convertor on that side) on the passenger side cylinder bank. Why the brand of gasoline makes a difference to this obviously aging and fast approaching end of life O2 sensor (I've already replaced the #1 O2 sensor on that same cylinder bank for the same misbehavior) is beyond me, but the CEL does seem to be related to the brand of gasoline.

Sincerely,

RockC.

 

Interesting about not being able to tell the difference between one brand of diesel fuel versus another. You may be seeing the benefit of minimum quality (e.g. cetane rating and sulfur levels) legislation in the state where you drive your diesel. In a prior lifetime when I owned a diesel car, I could tell when I was running winter blend versus summer blend - slightly louder ignition sound with the winter blend. As regards gasoline, having been burned once with questionable quality gas (I had to have the engine de-carbonized after only 10,000 miles; and I was using a name brand product), I have never strayed from the Chevron gas and haven't regretted my decision.

 

I have a MCS JCW. I spoke with John Michael Cooper about the gasoline in America. He said to run the highest cctane available! The octane recommendations were made by engineers from countries that have higher octane gasoline at the pump. Our octane is several points lower. These cars(especially the JCW cars) need the the higher octane to perform to their optimum. I recommend(for JCW cars) Lucas Oil Octane boost for spirited driving. You will notice a diference. You can buy it by the case directly from their Oklahoma distribution center at about a 40-50% savings. It is your car and your pocket book. The cost of driving a car at full throttle? PRICELESS!

 

??

 

Just a slight bend in this road . . . I live at 7000 feet. It used to be true that at higher altitude a given car could use a lower octane gas (or you could do as my dad did when we left the San Diego coast to visit the parents in Colorado-advance the distributor). The available gas, in fact, has lower octane for each grade. Regular is normally 86. Have the engine management systems simply changed all this? I read in a Ford Pick up owners manual today that, although regular 87 octane is specified, it is not recommended to use the regular 86 octane available in high altitude locations (this is a flex fuel V-8 . . . the E-85 available in Santa Fe is 105 octane). All of this seems to be consistent with the idea that engine management system will reduce efficiency, based on octane, to protect itself.

So I'm putting this all together with circumstancial evidence. Anyone know?

 

when incipient knock is detected the engine controller will retard the ignition to save the engine.

High compression is very critical to wringing performance out of an engine. Running the engine veryy close to incipient detonation (without actually running into detonation) is desired.

Even though the S has a low static compression ratio with supercharging the actual compression ratio is pretty high. And the higher cylinder pressures are most likely to occur at part throttle high load situations, not wot. (At wot the engine controller can ignore (stop monitoring emissions sensors) and feed the engine the best fuel/air mixture to maximize power output, which is a bit richer than usual and this works against detonation occuring.)

However, ignition retard is not without its downside. It raises exhaust gas temperature and costs performance (efficiency) and mileage suffers. Maybe enough to eat up any savings from buying a cheaper lower octane gasoline. Then there's the effect of higher exhaust gas temperatures on the engine internals and exhaust system.

Auto makers have nothing to gain by recommending a higher octane when none is needed, when it offers no benefit. If an automaker recommends a higher octane gasoline it should be used.

In emergencies a lower octane can be used but I'd not make it a habit.

Higher elevation lowers an engine's octane requirements. (Age can raise an engine's octane requirements, from combustion chamber deposits.) If you get up high somewhere and all you can find is 90 octane or 89 when your car's engine is spec'd to use 91/90 the lower octane is ok.

When I travel -- from sea level to upwards of 7000 to 8000 feet (and sometimes higher) with my high octane sipping car (not a MINI) with its two knock sensors I buy the highest octane gasoline for sale (barring the odd racing fuel pump) available from a name brand station that appears to do lots of business.

A recent article in a UK published car mag found that stale gasoline is common and costs peformance. Buying the freshest gasoline is nearly as important as buying the recommended octane.

Sincerely,

RockC.

 

My Check Engine light was intermitant lately. The MINI service guy told me cheap gas from Fry's, Costco is usually old.

 

Costco pumps high volume and has deliveries frequently, I doubt if their gas is old. However, it probably does not have the additive package that Top Tier brands and others have. Try Chevron, Shell, 76, Conoco or Phillips and see if that makes a difference.

 

Frankly, unless you live in the boondocks, or you frequent a gas station that prices their product at say, $2 above what everyone else is charging for the same grade of gas, you run a rather low risk of getting stale gas. Staleness becomes an issue for someone who buys in bulk and stores it at home, their farm, or.... This means you, Neil Young....

 

Not according to the results of the gas testing I read. Hi-test gas can go off in just days, and from the article stale gas was more common than expected and accounted for the engine under test on the dyno exhibiting sub-par hp/torque and driveability symptoms.

I see adjacent stations with just a 20 cent difference in prices and the one with higher prices has cobwebs growing across its driveways. People are starting to price shop gas and stations with higher prices than other stations are starting to see a drop off in business.

The writers of the article offered that better to wait in a line to buy gas and be (almost) assured of getting fresh gas, vs. being all by yourself when filling up and getting gas of some older vintage.

And given the cost of gasoline now, one wants to get the most for his money.

Sincerely,

RockC.

 

Just got the Mini the other day from a car dealer. They were so kind to fill it up with gas, 87 octane, car had no power and you could tell it was pulling timing. Filled up with 91 (live in AZ) and she drives great, can even hear the s/c a little. I always say use the least amount of octane and for the MCS 91 is probably as low as you want to go.

 

Does anybody mix octanes?

What about all of the talk regarding E85 and Ethanol in general.

Will that hurt or help our MINI's?

 

I often use mid grade and blend e-85 into the tank to get about 10% ethanol. That means like 1 to 1.5 gallons depending on the situation. The car runs good with that blend. I do the same thing with my Saab but with premium fuel . . . its owners manual specifies 93 octane while the MINI specifies 91. I don't know that the blend makes the cars run any better than straight premium but I have a bit of a committment to alternative fuels.

 

You may be going over the 10% ethanol mark by blending E-85. Ethanol is increasingly displacing MTBE as an oxygenate in gasoline. If you start out with a 10% ethanol blend and then blend some more ethanol (from the E-85), you could be getting to the 15% ethanol territory. That may cause some problems with the fuel system (one of which could be vapor lock in the summer), but I can't say for sure, as I don't have experience with a 15% ethanol blend.

 

The station where I buy e85 also sells e10 so I think they would be sensitive enough to post if their other gasolines had an ethanol content. Maybe not. The fuels in my area are not required to be oxygenated . . . although in Albuquerque, where I sometimes buy fuel, they do have that requirement in the winter.

I blended up to 20% for a few tanks in the honda I used to have. There was a definite odor at that level. I guess that is my fail safe. The only performance issues I had at the level was a slight drop in gas mileage.

 

E85 is 15% ethanol.