R 22

Rhodes 22


2 Cycle Engine Exhaust

What toxins are the 2 strokes putting into the environment? What little unburned gas and oil that are exhausted (from incomplete combustion) are rapidly evaporated by sunlight. As far as fuel efficiency, from what I've seen on the list as the gas burned in an hour with the four strokes isn't any better than my 2 stroke. I've watched people with four strokes trying to start their "clean" engines" and personally, I think it becomes a health issue for the person pulling on the starter cord. There are far greater sources of pollution today than what comes from outboard motors.

14 May 2000

The nearly 2X improvement in fuel efficiency between equivalent hp 4- cycle vs. 2-cycle engines is well documented. The extra fuel consumed by the 2-cycle engine ends up going out the exhaust. Only the low boiling components of the gas & oil are evaporated by the sun.

The water soluble components & the high boiling fraction is either dissolved in the water or dispersed by wave action. There are certain components of gasoline, such as the aromatic fraction & additives like MTBE that are not to be putting into either the water or the air. By not burning them, 2-cycle engines intrinsically dump about 2X more into the water & air.

But 2-cycle exhaust is much worse than the unburned fuel content would imply. You are familier with the oily smoke emitted in 2-cycle exhaust? Those particles of smoke represent the byproducts of partial combustion & pyrolysis of hydrocarbons. That smoke contains BAD SHIT like polycyclic aromatics, furans, dioxins, as well as other carcinogenic & biologically active materials. Some of these materials are biologically active in part per billion concentrations.

They are being laid down in the oily film on the surface of the water where they are incorporated by the smallest organisms at the base of the food chain. They are not volatile compounds, so they are not evaporated by the sun. From the microorganisms at the base of the food chain, these substances are bioconcentrated up the food chain. By using 2-cycle engines, we are literally pooping in our own nest.

As far as the products being used by owners of 4-cycle engines trying to get their motors going; the start-up period represents a tiny fraction of the time these engines spend running. 99+% of the time, a well maintained 4-cycle engine is emitting a tiny fraction of the total emissions of a 2-cycle engine &, even more importantly, emitting several orders of magnitude less of the really damaging BAD SHIT. The 2-cycle marine engine is just a really filthy piece of technology whose time has past.

Rummy, please note that I am not some "tree hugging" environmentalist. I am a hard headed pragmatic chemical engineer. I have spent a large part of my professional career designing, installing, starting- up, & trouble shooting pollution abatement systems on chemical plants.

There is good solid evidence to support what I've claimed above. The damage potential is real &, as responsible users of the marine environment, we must all try to be good stewards of the resource.

Roger Pihlaja
S/V Dynamic Equilibrium
14 May 2000

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