Can anyone tell me what the changes have been in the last hundred
years that allow a constantly increasing output from a given-size
engine? I'm not interested in turbocharging or supercharging in this
discussion. I read about 500 cubic-inch Cadillac engines from
thirty years ago putting out 145 horsepower, which is the same power
as my 82 trans-am put out in a 305 c.i., and is about the same
power some modern cars put out from a 1.8 or 2.0 liter four cylinder.
Other than four-valve engines and overhead cams, what has been the
big technology gain that has allowed the big increase in hp/liter? I
guess this also begs the question "How has fuel flow/hp decreased so
much in the same amount of time?" I know I've beaten this example to
death, but my '86 Jetta had a 1.8L in-line four, 8.0:1 CR, with two
valves per cylinder, just like my 'B', but put out 102 hp at the
tires versus 95 or so at the flywheel in a 'B', and got about 35-39
mpg in city driving. The only difference I can think of is the fact
that it was fuel injected (mechanical FI, though, no
computer-controlled EFI), and that it had an overhead cam. I can't
remember what the Jetta weighed, but it certainly wasn't LESS than
the 'B'.
I'm kind of amazed that we've been able to steadily wring more and
more specific power out of engine designs that haven't changed
radically in almost 100 years. Show a modern engine to someone from
1920, and after you got past the plumbing on top, he'd recognize most
of the parts.
Scott
Scott Gardner
gardner@lwcomm.com
www.lwcomm.com/~gardner
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