Garden power equipment 2-Stroke v.s. 4 Stroke

[Dmace]

Yes it burns some oil, but isn't gas just a highly refined oil?

You are arguing the wrong point, what is important is the total emission output not how it is generated. This is a very clean way to get the power benefits of a 4-stroke with the weight benefits of a 2-stroke.

First, yes gasoline is a highly refined oil but when you ADD OIL TO IT, it does not burn as cleanly as NOT ADDING OIL TO IT.

Secondly, how do you see this oil burning 4-stroke as having the weight benefits of a 2-stroke. The oil reservoir of a 4-stroke is not what adds to the weight, it's the valves, heavier casing, larger piston, etc... So this oil-burning 4-stroke does NOT have the weight savings of a 2-stroke just because it uses a gas-oil mix compared to a typical 4-stroke system. I am arguing about the total emission output and not how it's generated, a 4 stroke burning oil/gas will have more emissions then a similar gas engine not burning oil, simple fact.

 

[Highbeam]

If you burn the mixed gas instead of puking it out into the exhaust as in a standard 2 stroke then mixed gas can be burned cleanly in a 4-stroke engine. Not quite as cleanly as pure gas, but much more cleanly than a 2 stroke.

The issue isn't whether a 4 stroke on straight gas is cleaner than a 2 stroke on mixed gas but whether a 4 stroke on mixed gas is cleaner than a 2 stroke on mixed gas. I believe it is. Further, I believe that a 4 stroke on straight gas is only slightly cleaner than the 4-stroke on mixed gas. You'd never notice.

We're not talking about burning straight oil or something as heavy as diesel. These very high 50:1 ratios of fuel to oil don't appreciably thicken the gas, they just change the lubricity properties and add a color. Splitting hairs. Really, I'm not concerned with the pollution as much as I am with the weight and running characteristics.

 

[turbo36]

First, yes gasoline is a highly refined oil but when you ADD OIL TO IT, it does not burn as cleanly as NOT ADDING OIL TO IT.

Secondly, how do you see this oil burning 4-stroke as having the weight benefits of a 2-stroke. The oil reservoir of a 4-stroke is not what adds to the weight, it's the valves, heavier casing, larger piston, etc... So this oil-burning 4-stroke does NOT have the weight savings of a 2-stroke just because it uses a gas-oil mix compared to a typical 4-stroke system. I am arguing about the total emission output and not how it's generated, a 4 stroke burning oil/gas will have more emissions then a similar gas engine not burning oil, simple fact.

If it is a simple fact then show me the proof. Do you have a chart that shows the emission levels for a straight gas engine of comparable size and power? The oil that gets burned is a very small amount and since it does get burned so cleanly it contributes to the power output of the motor so it isn't a total energy loss.

This engine is lighter then a typical 4-stoke because there is no sump, pump or oil. While not as light as a 2-stoke (Stihl say's 6 oz. heavier) it does put out more torque and HP so it could be argued that the engine size could be reduced to save more weight.

 

[Dmace]

If it is a simple fact then show me the proof. Do you have a chart that shows the emission levels for a straight gas engine of comparable size and power?

Seriously...? You need a chart to tell you that an engine that burns gasoline alone will omit less emissions then the same comparable engine burning gasoline and oil mixed. I don't care if it's 100:1 ratio, there is still oil mixed into the gas and that oil is not 100% burned so it has to come out somehow. I'm done arguing a moot point, you want to pay the premium for a 4-stroke and still have to mix oil and gas and smell that exhaust when in closed areas, then go for it.

 

[2manyrocks]

I thought that the way 2 strokes are designed to intake fuel and exhaust, that they inherently didn't burn all of the fuel in each combustion cycle. But they were mechanically simpler, lighter and more noisy than 4 stroke engines of the same size.