Re: OT: You know you're from California if...

From: Bob Stephens (stephensyomamadigital_at_earthlink.net)
Date: 02/25/05 

Date: Fri, 25 Feb 2005 19:46:03 GMT

On Fri, 25 Feb 2005 11:51:32 -0700, Jim Thompson wrote:

> On Fri, 25 Feb 2005 18:49:04 GMT, Bob Stephens
> <stephensyomamadigital@earthlink.net> wrote:
>
>>On Fri, 25 Feb 2005 10:20:00 -0800, John Larkin wrote:
>>
>>> The VW has a knock sensor that theoretically adjusts mixture or
>>> something to just before detonation, regardless of the octane. So
>>> theoretically I get more power climbing hills if I buy better gas, so
>>> I do. I have no idea if it actually helps.
>>>
>>> John
>>
>>I'm not following your reasoning. If in fact the 'knock sensor' works as
>>described, and your detonation point is fixed relative to the cycle
>>regardless of octane (a combustion retardant), why not buy the cheapest gas
>>available?
>>
>>Bob
>
> You misunderstood... timing is advanced until knock is detected.
>
> ...Jim Thompson

Ok got that. I still don't see where the extra power comes from using
higher octane gas.

1)VW device advances timing until knock detected and backs off one tick.

2)Octane added to gas to retard combustion - preventing pre-ignition or
knock.

It seems to me that these two scenarios are attempting to address the same
problem by different approaches. And it also seems that up to a point,
scenario 1 will adjust the timing to optimize the ignition point in the
combustion cycle irrespective of the amount of octane you throw at it.
Lower octane gas is more volatile, so if your 'regulator' circuit is
controlling the timing such that it is just this side of knock,thereby
getting the full explosive benefit of the pressurized gas vapor, why isn't
this as good as it gets?

Bob

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