Could a 2 stroke be green?
 

I was hacking away with a string trimmer at work recently, and it got me thinking. With sufficiently advanced technology and engine management, would it be possible to make a 2 stroke engine that could match the efficiency and emissions standards of conventional 4 cycle ICE's? Obviously a 2 cycle engine has a large advantage in power/weight ratio, since the cylinder is firing twice as much. Reducing weight is huge when it comes to improving efficiency.

The idea of 2 cycle engines in cars is not new. Back in the early-mid nineties Jeep had a concept vehicle called the Ecco which was powered by a 1.5L 3 cylinder direct injection 2 cycle engine.

Jeep ECCO Concept - Mojeepin.com

I doubt it, but by 2011 the EPA is requiring cats on all lawn equipment and such.

Given enough development money and a suitable incentive I think ring dings could be made to be green.
Direct fuel injection and a separate oil system is certainly a starting point but then who would be willing to pay for that on a lawn trimmer or leaf blower?

Pete.

Just to clarify, I was talking about using 2 cycle engines in cars.

2 stroke wont be green since it "burns" oil

2 cycles in cars? What's to gain really? Even if you could the issues with increased wear I think would reduce the value there.

2 strokes in cars eh? I remember reading in an old dirtbike magazine that they converted a CR500 engine to run on alcohol and they used vegetable oil for lubrication. It also made some rediculous amount of hp and the top speed near 130mph was traction limited...
It also drained the 1.5 gallon tank in 10 minutes... The emissions were quite "green" but the amount of fuel used makes it impractical.

Probably the most advanced 2 stroke engines available now are in snowmobiles and some are getting nearly the same mileage as 4 stroke sleds, within 10-15%. Total cost of ownership is still probably in the 2-strokes favor as they are far cheaper to buy initially and a rebuild is much cheaper but still required more often. An 800cc 2 stroke snowmobile drivetrain would make a Geo metro into quite the performance machine but I doubt it would get much better than 35 mpg.
Ian

I doubt a two-stroke would ever meet even mid-70s emissions standards.

The two-stroke's big edge is it lack of a valve train. But that means port induction/exhaust. So a port uncovers with the combustion event still going on. Unburned hydrocarbons (VOC) are emitted.

A lot of smart cookies tried to save the two-stroker but the last of them died out before Jimmy Carter was out of office.

Like everything else, engineering has a history.

my Tomos scooter has a 2 stroke engine, oil injection and a catolitic converter and because of that has very dry exhaust, unlike the old ones that had greasy exhaust.
I've also ran 10% veggie oil in 4 stroke gas engines with great luck, had it burn completely and read about people running it in 2 stroke chain saws with good luck and no ill effects.