How much could internal combustion efficiency be improved by eliminating pollution controls?

[FarCenter]

Polution controls were put on cars beginning in the '60s to control a variety of pollutants in tailpipe emissions.

Prior to that, in the '50s, cars got relatively good gas mileage, even though they were heavy and the engines were relatively primitive.

Detroit adapted at first by detuning the engines and increasing displacement so that more complete combustion was achieved. This was done at the expense of mileage, leading the the gas guzzlers of the '70s, which also had lousy performance.

The catalytic converter, an expensive device containing platinum and similarly pricy metals, was introduced so that incompletely burned hydrocarbons could be burned in the converter before going out the tailpipe. Obviously, this disapates energy as heat in the converter, instead of propelling the car.

All this was done before the realization that carbon dioxide, a product of the complete combustion of gasoline, was itself a pollutant and would cause climate change.

It is now clear that the tradeoff of producing more carbon dioxide as a means to produce less carbon monoxide, nitrogen oxides, partially burned hydrocarbons, etc is not a particularly good one.

So the question is, can you now design a gasoline engine which is highly efficient?

All the modern technologies of a multitude of sensors, computer controlled ignition, precise electronic fuel injection directly into the cylinders, turbocharging and heating of incoming air, 6-speed automatic transmissions allowing operation in a more optimal rpm band, etc, could be applied to the engine.

To be efficient, it would have to pretty completely burn the fuel-air mixture, and hence would necesarily have limited emissions.

Besides which, not importing platinum from Russia and South Africa would help our balance of trade.

[MineralMan]

1. Frankly, that's about where we are, but with the controls.

Automotive engines are far more efficient today than ever before. The technologies you mention make them that way.

Those old engines in the 50s were horrible, efficiency-wise, and their mileage was not nearly as good as you think.

[FarCenter]

2. They might have been horrible, but 16-17 mpg is competitive with SUVs.

My recollection is that a full-size sedan with a inline 6 or small V-8 would get about 15-20 mpg.

My dad had a '53 Ford Custom sedan 4-door with the small, flathead V-8, 3 speed manual, and it got about 16-17.

The automatic tranmsissions were really ineffcient back then, but that is no longer true.

[MineralMan]

3. And now, a full-size sedan with a V6 or V8

gets around 25 mpg on the highway. That's true of my parents' big Ford Crown Vic.

I had a Lumina minivan, with a 3.6 liter V6, and it regularly did almost 30 mpg on the highway.

There's just no comparison between modern engines and those of the 1950s when it comes to efficiency.

Add to that the pollution those old engines spewed and there's no going back.

No question, though, if you put all the modern technology on those engines, they'd do a lot better than they used to. Basically, that's what's going on now. Add the catalytic converter, and you get rid of most of the rest of the pollutants. Other than that, though, the modern tech is what gets you both high efficiency and low pollution.

Now, if cars could be made lighter, that would help economy a lot. But, much of that weight is in safety equipment, and isn't going away.

[gristy]

4. "Prior to that, in the '50s, cars got relatively good gas mileage"

Suggest you research and provide support for this claim.

[safeinOhio]

5. I have a stock 1950 Buick Special

17 mpg at 50 mph.
Rebuild the engine every 70,000 to 80,000 miles. It has this huge FireBall Eight that weighs a ton and only get about 130 hp. It is a wonderful car and I love it, but requires way more maintenance than any modern car. We forget what it was like.

[Sgent]

6. As bad as CO2 is

I don't think you can compare it to NO, CO, and many of the other gasses that have been removed (or reduced) by current technology.

Those gasses were much more toxic, and much more of a threat to the Ozone layer, other drivers, etc, than CO2 is. Yes in time CO2 emissions will do a lot of harm if not reduced -- but those did a lot of harm right now.