Over recent years, 2-stroke engines have gained a bad name from people concerned with emissions. To be candid, older 2-stroke engines contribute to the filthy air in many cities around the world today.
Why then, did RevoPower elect to use 2-stroke engine instead of a 4-stroke engine?
The answer is in two parts. First, modern 2-stroke engines can be produced which actually burn more cleanly than the same size engine in a 4-stroke configuration. RevoPower uses the latest and cleanest technology to ensure compliance with the strict EPA and CARB guidelines.
In addition, there are other major benefits of 2-stroke engines over 4-stroke engines. These include:
- 2-stroke engines work in any orientation, which is required in the Wheel. Standard 4-stroke engines have problems with crankcase oil unless they are upright.
- 2-stroke engines do not have valves, which simplifies their construction, lowers their weight and allows the Wheel to be small enough to rotate between the forks of a bicycle.
- 2-stroke engines fire once every revolution, while 4-stroke engines fire once every other revolution. This makes 2-stroke engines more powerful.
- 2-stroke engines are lighter, simpler and less expensive to manufacture.
Therefore, after considerable exploration, design and comparison, we determined that a 2-stroke engine would best suit our requirements.
Below is a summary of the issues with older 2-stroke engines, and RevoPower's approach:
| :: Traditional Criticisms of 'old' 2-Strokes |
:: RevoPower Solution |
| Older 2-stroke engines don't last as long as
4-stroke engines. |
RevoPower's design keeps the engine speed to a minimum and utilizes chrome plated cylinders and gravity cast pistons and a rigorous QC system ensures the engine will last for a long time. |
| 2-stroke engines have lower efficiency, yielding fewer miles per gallon. |
The Wheel utilizes an engine with a modern scavenging system for minimizing emissions and increasing fuel economy. |
| 2-stroke engines produce more pollution than their 4-stroke counterparts. |
RevoPower's engine meets all EPA, CE and CARB emissions requirements--if these regulatory agencies required a lower CO level, micro 4-strokes would not meet the emissions requirements where a 2-stroke would. |
| The combustion of the oil in the gas makes 2-stroke engines 'smoky'. |
This is only true with very, very low-quality engines, we utilize modern engine technologies that burn without any visible smoke emissions. |
In conclusion, RevoPower's 2-storke engine is clean and meets all emissions requirements specified in 40 CFR § 90 - Control of Emissions from Nonroad Spark-Ignition Engines at or Below 19 Kilowatts. This specification dictates that the Wheel is viewed as a Class I-A Engine for Exhaust Emissions Standards. These standards are: 50 grams per kilowatt-hour of HC+NOx; and 610 grams per kilowatt-hour of CO. The major benefit of RevoPower's 2-stroke engine is that its CO emissions is substantially below this 610 g/kw-hr threshhold. Stay tuned for an update on this section; we will post the results of our emissions testing.
