Tuesday, March 08, 2005

Stihl 4-Mix Engine

The two-stroke has always been the engine of choice for string trimmers and other handheld yard machines. Fast and powerful, its gas-oil mixture provides both fuel and lubrication, so there's no oil to check. Unfortunately, two-stroke exhaust is extremely dirty, and emissions laws may eventually doom it. Manufacturers are developing engines that marry the power of the two-stroke with the cleaner emissions of a four-stroke. One of the first is Stihl's 4-Mix. A unique design connects the intake manifold to the crank-case, meaning that unlike other four-strokes, the new engine can use a standard 50:1 fuel-oil mix and do away with the oil reservoir. Vacuum and pressure drive the mixture through the crank-case, so the engine can operate inverted (which would drain a normal four-stroke dry). Stihl says its new engine gets 5 percent more horsepower and 17 percent more torque than a comparable two-stroke. Look for it on a range of products, including pole pruners ($430–$600), string trimmers ($350–$400) and more.

This new engine is very efficient. The mix is convienient so that it doesn't pollute the air. I'm not really the kind of person who would know what all this means so it doens't make much sense at all. But it is interesting that there are these different types of engines and varities that I wasn't aware of and now I see why its so important.


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