Re: If you want to be invisible on a car lot...

Mark Hickey wrote:
Bill Baka <bbaka@xxxxxxxx> wrote:


Mark Hickey wrote:

Bill Baka <bbaka@xxxxxxxx> wrote:


Real wheel drive with a stick for me. Those I can work on for fun and mileage. A little gear change can turn a 25 MPG pig into a 40 MPG car.


Bill, there are times when I'm sure you have a problem with the laws
of physics.

This is one of those times.

You can gear a car to reduce the engine RPM by 1.4 times, but why
would it not require more fuel per revolution to produce the same
amount of work?

Answer that one and you've solved the world's energy crisis (and
disproved Newton).

Mark,
In this case I can really suggest you think before you post.
Engine wear and energy wasted work as at least the square of the speed.
You don't think those pistons want to go up and down at 3,000 RPM, do you? It takes more energy to drive the pistons than the car sometimes.


Bill, you're just wrong. Period.

Internal engine friction is similar to hub friction on a bike. It's
significant, but you're not going to decrease your energy requirements
for cruising at highway speeds by 50% by eliminating it. If what you
said was true, the gas mileage of a Mustang and an F-350 would be
similar since they have the same engine - though presumably the truck
would have higher gearing, so it would get better mileage in your
universe.

As with a bike, the VAST majority of energy goes into overcoming
aerodynamic resistance. It still takes the same amount of work to do
that, no matter what speed the engine is turning. To get the benefit
you're claiming, the aerodynamic loading would have to be almost
negligible.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Mark,
You must be one of those who really flunked physics, BADLY.
I did this with a 1961 Rambler flathead 6 and took it from 25 MPG up to 38 MPG+ on the highway at 65 MPH. If you have a car, and a stopwatch, and can make a fairly reliable measurement, then try something before you go all self righteous on me. I took my 4,400 pound 1966 Chrysler with the 2.73 rear end and 440 engine, and timed the coast down from 70 to 60. It was 15 seconds in neutral, but only 7 seconds in gear with a 727 automatic. The SIMPLE deduction is that half the energy was wasted just rotating the engine.
Big DUH, bicycle genius.
Do the math and see how much energy it takes to make each 2 pound piston accelerate and decelerate up and down at 2,500 RPM. Multiply by the number of pistons and you will see a lot of energy going for nothing.
Automakers don't really give a *** because they want to keep their engines at the point where stepping on the gas produces a noticeable speed up. Running at only 1,000 RPM will still produce enough power to go 65 MPH, about 12 to 14 HP, but no zoom when you hit the gas.

Go stand in the corner.

Bill Baka
.