[Vwdiesel] Fwd: Altitude compensation (James Hansen)
Libbybapa@wmconnect.com
Libbybapa at wmconnect.com
Sun Sep 4 18:33:58 EDT 2005
In a message dated 9/4/05 3:33:07 PM US Mountain Standard Time, Libbybapa
writes:
> In a message dated 9/4/05 1:51:05 PM US Mountain Standard Time,
> cjb at midrivers.com writes:
>
>
> >> "I don't know, but I doubt very much there are high enough compression
>> engines on the consumer market that REQUIRE high octane rated fuel."
>>
>
> IMO it would depend on the stock timing setting and the range of retard that
> the knock sensor ignition could perform. Regardless, the compression ratio
> is certainly not the only factor. Ignition timing setting is as much of a
> factor. When a vehicle utilizes a knock sensor, usually it is timed within the
> range where the engine will start knocking. The knock sensor retards the
> timing to just before that point. You can get an air-cooled engine with a 7:1
> compression ratio to knock easy enough, just advance the timing far enough.
> My point still makes sense to me. An engine running on a lower octane fuel
> will knock less at higher altitudes. Therefore the knock sensor will retard
> the timing less and the injection will enrich less. My point: A knock sensor
> controlled engine will run on lower grades of fuel at higher altitudes with
> less of an effect on mileage and performance. Sorry for the in depth
> non-diesel topic.
>
>
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