[Diy_efi] Timing Advance Curve?

Mike erazmus at iinet.net.au
Fri Dec 20 04:02:43 GMT 2002


Hugh,

Please quote the authoritative source of your information
that "octane has everything to do with speed of burn" ?

rgds

Mike



At 10:15 AM 19/12/2002 -0000, you wrote:
>
>Mike wrote "Isnt octane a measure of the fuels ability to resist knocking
>" - yes
>
>This is at its most basic level achieved by altering the fuel to burn more
>predictably and slowly by removing the most volatile components or modifying
>the way that the most volatile components burn with additives.
>
>In short octane has everything to do with the speed of the burn.
>
>High octane fuels do not necessarily give the most power. Brian Geddes
>posted a couple of days ago that his Miata did not knock regardless of
>ignition timing. In this situation, it might be worth trying a lower octane
>fuel which when optimised for timing and fuel mixture may give a higher
>cylinder pressure through the faster burn and therefore slightly more power
>even though the calorific values of the high and low octane fuels are
>similar.
>
>Do not confuse high octane with high energy as unless it is a racing fuel,
>the two do not normally go hand in hand.
>
>Hugh
>
>----- Original Message -----
From: "Mike" <erazmus at iinet.net.au>
>To: <diy_efi at diy-efi.org>
>Sent: Thursday, December 19, 2002 5:25 AM
>Subject: RE: [Diy_efi] Timing Advance Curve?
>
>
>> At 11:23 AM 18/12/2002 -0800, you wrote:
>> >--- "Geddes, Brian J" <brian.j.geddes at intel.com>
>> >wrote:
>> >Well, if you are talking in that sense, simply up the
>> >octane to cover the extra compression.  However, you
>> >can run into a point of diminishing returns as far as
>> >power output at higher rpms with the slower burn...
>>
>> Huh ?
>>
>> WHat has octane to do with the speed of the fuel burn ?
>>
>> Isnt octane a measure of the fuels ability to resist knocking ?
>>
>> Mike
>>
>>
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>
>
>
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