Re: air - fuel ratio

On May 7, 2:12 pm, jim <".sjedgingN0sp"@[EMAIL PROTECTED]
> wrote:
> Don Stauffer in Minnesota wrote:
>
> > If we had higher octane fuels without serious environmental
> > consequences, we could have better fuel milage.  The higher CR that
> > modern fuels allow is one reason fuel milage is better on a ton-mile
> > per gallon basis than it was pre-WW2.
>
> Where did you come up with that? It is my observation that 1940 cars
were
> pretty heavy and quite fuel efficient compared to cars in the 50's of
the
> same weight. Not that anyone cared in the 50's about fuel efficiency,
but
> fuel efficiency was an issue before WW2 so cars were designed to be more
> fuel efficient. It wasn't until the early 70"s that anyone much cared
> about fuel efficiency. Increased Fuel efficiency in the late 70's and
> eighties was mostly achieved by shedding weight.
>
> -jim
>


No, higher CRs and higher operating temperatures (sealed cooling
systems) also contributed to higher fuel efficiency these days.
Better combustion chamber design allows higher CR today without higher
octane.  Not many hemi head designs these days.