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Old 11-23-2011, 01:38 PM
jarhed1964 jarhed1964 is offline
Officially Welcomed to the 'Fest
Location: Charlotte, NC
Join Date: Apr 2010
Posts: 714
Mein Auto: '99 528i Sport, '05 530i
Originally Posted by seemyad View Post

This post goes toward validating the areguement against using low octane fuel vs recommended high octane. I always use 9x grade and some tried to argue in favor of 8x. Lower octane gas is less stable than high octane (under pressure). Pressure exerted on 8x by the pistons may prematurely ignite the 8x crap-gas (aka knocking). Our engines correct for the premature ignitions by changing the timing (prevents knocking). Yet people still try to argue in favor of using crap-gas based on science that has zero to do with the reason bmws require high octane fuel. Bmws have a high compression ratio as with most "preformance" cars. Higher the compression the more likely 8x will ignite prematurely which is then corrected by throwing off the engine timing to compensate.

crap-gas misfired timing will impact your fuel-air mixture. which, in turn, can lead to more carbon buildup over time.

thank you for this post as a picture says 1000 words. Not just because it validates my stand, moreso because it is very educational for us all.


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