XPost: misc.phone.mobile.iphone, comp.mobile.android   
   From: pmcook@gte.net   
      
   On Thu, 10 Dec 2015 12:12:08 -0500, nospam wrote:   
      
   > again, that depends on the engine.   
      
   Actually, the fuel was *designed* into the engine, but, a lot depends on   
   the current timing of the spark advance, whether the knock sensors   
   are working, whether the EGR is working to cool the combustion   
   chamber, whether the cooling system is working to cool the cylinder   
   walls, whether the variable valve timing is working (e.g., VANOS   
   in bimmers), etc.   
      
   > some engines adjust timing depending on the fuel and others don't.   
      
   Actually they don't.   
      
   My bimmer has two piezoelectric knock sensors mounted on the engine   
   which detect knocking, and, if they detect knocking, this tells the   
   Siemens DME to retard the timing.   
      
   > for the former, there can be a performance improvement with higher   
   > octane fuel. for the latter, it's mostly a waste.   
      
   You can't get a performance improvement with higher octane rated   
   fuel *unless* you were knocking in the first place.   
      
   > maybe you drive shitboxes that fall into the latter category but not   
   > everyone does.   
      
   I have a bimmer and a beemer.   
   The bimmer has two piezoelecric knock sensors mounted on the passenger   
   side of the M54 engine block.  The beemer does *not* have knock sensors,   
   and, while it's water cooled, it still runs hotter, so, it's prone   
   to knocking on the wrong fuel for the conditions.   
      
   >> They even think that this "cleans" the engine better (as if octane   
   >> ratings had anything to do with cleaning, per se).   
   >   
   > it might burn a little cleaner but it doesn't clean the engine.   
      
   It doesn't burn any cleaner. It just resists knocking better.   
   The cleanliness, as you know, is due mostly to polyetheramine   
   detergents, which as absolutely nothing, per se, to do with the   
   AKI rating.   
      
   You know that.   
   I know that.   
      
   But a lot of dumbshits out there don't know that.   
      
   >> And, yes, I know all about polyether amines also (which are the   
   >> main detergents in American fuels).   
   >   
   > but not much about engines.   
      
   Test me.   
   I know a *lot* about "my" M54 engine.   
   Ask me anything about it.   
   I know the BMW E39 inside and out.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)