Dirty 2 Strokes: An environmental Report

CONVENTIONAL DIRTY TWO-STROKE ENGINES

Carbureted two-stroke engines are typically used as the power source for "two-wheelers" (i.e. motorcycles, mopeds, etc.)..The high hydrocarbon emissions from carbureted two-stroke engines result from the scavenging process used. Scavenging refers to the process by which the burned exhaust gasses are flushed from the engine. In a conventional "carbureted" two-stroke engine the fuel is entrained in the intake air stream before the combustion air enters the crankcase.

The charge is compressed in the crankcase by the underside of the piston, and enters the cylinder when the piston uncovers the transfer ports. Combustion products from the previous cycle are forced or "scavenged" from the cylinder with this new air/fuel charge. Unfortunately, the exhaust ports are also open at this time, allowing 30%-40% of the fuel to be lost directly into the exhaust stream. At idle conditions the losses can be as high as 70%. ..

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A Direct Injection Solution?

DIRECT IN-CYLINDER FUEL INJECTION

Direct injection (DI) is a technology that has shown the ability to greatly reduce emissions from two-stroke engines. In a DI system the carburetor is eliminated, and the fuel is introduced into the combustion chamber via an injector mounted in the top of the chamber’s cylinder head. This allows exhaust products to be scavenged from the cylinder using air only.

Fuel is injected into the cylinder later in the cycle, greatly reducing the amount of unburned fuel that is allowed to escape during scavenging. Scavenging losses of unburned fuel are virtually eliminated, resulting in much lower hydrocarbon emissions and more efficient fuel consumpt.

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FIELD TESTING

...The converted vehicles all contained Kawasaki 125cc (9 KW) carbureted engines..

Envirofit's field tests prove that our retrofit kit reduces hydrocarbon emissions by 89%, carbon monoxide emissions by 76%, carbon dioxide emissions by 26%, increases fuel efficiency by 34.8%, and decreases oil usage by 50%..

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