20 Mar
2001
20 Mar
'01
9:50 a.m.
To drag this topic kicking and screaming back towards
the list topic, as
many engines over the past 10 for 15 years have used computerised engine
management systems, why have we not seen much improvement in specific fuel
consumption? I would have thought that the systems would be able to run
the engine at optimum mixture and thus give a significant improvement in
economy.
What processors have been used in these systems over the years?
Lots of motorola, 68k etc.
A well adjusted carburetor does a pretty good job, but a modern engine is
close to amazing at just how well the it works given the cost. I drive a
4,000 lb full size Lincoln, with a 285 hp engine that gets 18 mpg around
town, and close to zero emissions. Highway mpg hasn't changed much,
because getting a correct mixture at a constanst cruise speed isn't nearly
as hard of a job and carbs did just fine. The achievement is to get low
emissions and good mpg during short trips around town, while the engine is
still cold etc.
Also my guess is that 'average' engine hp has about doubled in the last 2
decades, and that reduces mpg.