[OT] Engine braking

[Walter Bright]

On 8/1/2013 12:39 PM, Andrei Alexandrescu wrote:
> You betcha. Related, you destroyed the myth that engine braking is any bad, but
> I bet money nobody changed opinions.

For an engine designed for it, sure. For an engine not designed for it, no. A 
carbureted engine is still going to have the unburned gas problem (and you're 
not going to be very green pumping out semi-burned hydrocarbons out the 
tailpipe). I don't know at what point injected systems began shutting off the 
fuel when backdriving.

> Also, there is a beauty about electrical engines - their theoretical efficiency
> is 100%, they are simple, principled, entropy-neutral, and work on conservative
> laws. (Batteries are more unwieldy though.)

You're right, it's all about the batteries. They're a gigantic problem that, 
while there are incremental improvements, is still far from a solution. But 
gasoline engines are also getting incremental improvements. Modern ones are way, 
way better than the ones from the 60's in just about every aspect.

There's an inherent efficiency in gas cars in that the energy is generated on 
site. For electric cars, the energy is generated elsewhere (at the power plant), 
and then you're faced with all the losses from transmitting the energy, storing 
it, and recovering it. It's a tough hill to climb. Gasoline is pretty remarkable 
in its energy density and portability.

BTW, with a manual trans, you can get quite a bit better mileage than the EPA 
ratings. Google "hypermiling" for ways. I do that stuff routinely.