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
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.
S/V Dynamic Equilibrium
14 May 2000