98RON for non CAT equipped bikes

[dmsantam]

I noticed in the manual for my r1100rt that it recommends minimum 98 RON fuel for non CAT equipped bikes, but 95 for CAT equipped bikes. Why the difference? I have a 1995 with no CAT and have been running 95 without any perceivable issue. 

 

cheers

[dirtrider]

11 hours ago, dmsantam said:

I noticed in the manual for my r1100rt that it recommends minimum 98 RON fuel for non CAT equipped bikes, but 95 for CAT equipped bikes. Why the difference? I have a 1995 with no CAT and have been running 95 without any perceivable issue. 

 

cheers

Evening  dmsantam

 

That's a good question, the engines are basically the same & the catalytic converter itself should not have much effect other than it requires no-lead gasoline. 

 

So my guess is that it is more Lambda sensor related (better more precise fuel control),  or is CCP (fuel/spark mapping) related. The cat equipped engine uses different fueling & spark mapping than the non cat equipped engine.

 

I can't say what drove BMW to make those suggestions but I have seen little quirks in vehicle testing data that could drive a different fuel requirement in certain vehicles under certain situations. 

 

 

 

[King Herald]

I vaguely remember back in the day hearing that leaded petrol will destroy the cat, but I’m not sure if the 98 RON fuel has lead in, to achieve the higher octane,  while 95 doesn’t. 

[dirtrider]

48 minutes ago, King Herald said:

I vaguely remember back in the day hearing that leaded petrol will destroy the cat, but I’m not sure if the 98 RON fuel has lead in, to achieve the higher octane,  while 95 doesn’t. 

Morning King Herald

 

Leaded fuel will absolutely ruin a catalytic converter as well as poison the o2 sensor. 

 

Back when Dmsantam's manual was written there very well could have been lead in European 98 RON fuel as a lot of performance vehicles of that era still required leaded fuel.   

[King Herald]

4 hours ago, dirtrider said:

Morning King Herald

 

Leaded fuel will absolutely ruin a catalytic converter as well as poison the o2 sensor. 

 

Back when Dmsantam's manual was written there very well could have been lead in European 98 RON fuel as a lot of performance vehicles of that era still required leaded fuel.   

Morning DR,

I just got into Google, and found that leaded petrol was finally phased out totally in the U.K. in 1999, so that would definitely explain the 98/95 RON issue.
 

Oddly enough, petrol is still advertised as ‘unleaded’ at gas stations here in the U.K., as if there’s a choice to buy any other type. 

 

The price is per litre, so about $6.50+ a US gallon. 
 

[dmsantam]

That could explain it, but I would have thought they'd just say "unleaded fuel required", rather than change the octane number required. It does state leaded for those without a cat, and unleaded for those with a cat, but it _also_ states a different octane for each. 

[dirtrider]

12 hours ago, dmsantam said:

That could explain it, but I would have thought they'd just say "unleaded fuel required", rather than change the octane number required. It does state leaded for those without a cat, and unleaded for those with a cat, but it _also_ states a different octane for each. 

Morning  dmsantam

 

With-a-cat. uses a different fuel & spark map in the fueling computer than without-a-cat. As the with-cat. uses a lambda sensor for fueling control.