Octane

[Scott Miller <sdmiller@xxxxxxxxxxxxxxxx>]

Laurent, to clarify the fuel octane comments...

If your car does not ping (aka knock), then you don't need higher octane
fuel.  Except:  If your car has a knock sensor, it adjusts timing (or
some such) so that it won't ping, regardless of the fuel used (more or
less).  You could experiment with higher octane fuel and see if the car
goes faster, in which case you might benefit from higher octane.  

If your car pings, but you didn't do anything to increase cylinder
pressures (high compression pistons, turbocharging, supercharging,
etc.), then it may be an indication that something is wrong with the
engine - carbon build-up, timing too far advanced,  running too hot,
etc.  Such problems should be addressed.

Hope that clears it up.

Scott Miller
Golden Gate Chapter
BMW CCA #44977

>Date: Fri, 04 Dec 1998 07:58:17 PST
>From: "Laurent Tambayong" <m3usa1@domain.elided>
>Subject: 100 octane fuel
>
>Scott Miller mentions that high octane gas worths only with high 
>compression pistons.  M3 has 10.5:1 ratio isn'it.  Would it be 
>considered high enough?  What about forced induction engines??
>
>
>Regards,
>
>Laurent Tambayong
>BMWCCA#143146
>Buckeye Chapter

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