The BTUs stay the same.  The available energy stays the same.  What changes
is the efficiency of burn and the efficiency of the mechanical systems it
drives.

Furnaces in the home have gone from being 60 to 65 percent efficient to
70-75 and now 85-90 percent.  Energy to drive the furnace has gone down as
well as electric motors to drive the fans have gotten much smaller and use
far less energy as well.

Engines on vehicles have gone from the extremely poor efficiency of the 60s
muscle car to the current run of performance vehicles.  Current engines that
are much smaller use far less fuel and put out less horsepower but linked to
better engine management and transmissions and lighter vehicles perform
right at the same levels.

To use the subie mod as an example
My aircooled engine got 15mpg on a good day and maxed out at 35 to 40 mph on
many of the slopes I drive around here.
The subie engine with its much more modern computer controlled engine
management gets 18 to 20 mpg and will push me right up all of those same
slopes at or above speed limit.  Also puts out over double the horsepower.
Mathematically that puts the efficiency of the subie engine at almost 40
percent above the orig aircooled engine. 1982 engine built with 1974
technology.  It was old when built.

Another reason I am looking at some of the modern diesels.  However they
seem to think they made them out of gold or platinum.

jimt

On 11/1/05 11:36 AM, "Kim Brennan" <kimbrennan@MAC.COM> wrote:

>
>>
>> What else???
>>
>> Is it really possible to get more BTU's from a pound of fuel than a
>> pound of fuel has??  What good does better mixture control and
>> vaporization actually do? Given better mixture control and vaporization,
>> can fuel efficiency actually be increased beyond where it is now, just
>> on that basis?
>>
>