Clean Snowmobile Facts
- CONCERNS
- National Parks
- Air Quality
- Water Quality
- Personal Exposure
- Other Concerns
- SOLUTIONS
- Engine Technologies
- Two-Stroke Engine Principles
- Two-Stroke Engine
Modifications - Four-Stroke Engines
- Electric Snowmobiles
- Fuels & Lubricants
- Oxygenated Fuels
- Biodegradable Lubes
- Low PM Lubes
- Clean Snowmobile Challenge
- What You Can Do
- REGULATIONS
- MONTANA ISSUES
Solutions
Overview
Some view the controversy over snowmobiles in America's national parks as a controversy about technology and its uses. At the heart of the technology debate is the two-stroke, spark ignition engine, patented in England in 1881 by Sir Dugald Clark.
While the two-stroke engine has an advantageous power to weight ratio, it is noisy and releases high levels of hydrocarbons directly into the atmosphere. For the latter reason, two-stroke engines were gradually abandoned for use in automobiles in the 1960s, although they remain the engine of choice for numerous small engine applications, including lawn mowers, chainsaws, water craft, motorcycles and scooters, and off-road vehicles such as snowmobiles and all-terrain vehicles.
The two-cycle engine used in most snow machines emits 20 percent to 33 percent of its fuel unburned. This exhaust includes lubrication oil, which is mixed in the fuel at a ratio of 50 parts gasoline to one part lube oil (50:1). Most of the visible haze in two-cycle exhaust is from lube oil.
The two-stroke engine has undergone numerous changes over the decades, but the general principle remains the same. Instead of allowing combustion and exhaustion of spent gases to occupy a full stroke, the two-stroke engine shortens - to a tiny fraction of the duration of a stroke - the time in which fuel is introduced to the combustion chamber and in which spent gases are exhausted.
New technologies and variations on old technologies hold the promise of reducing emissions and noise associated with two-stroke engines. You can read more about these technologies in these pages.
