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An End to Outboard Halitosis
THE EPA MANDATES A CONTINUED CLEANUP OF ENGINES
By Tom Ireland
There is no doubt that much progress has been made in cleaning up our outboards so they are far friendlier, environmentally speaking. I was having lunch at a marina recently and watched a 10-year-old V-6 outboard start up. The smoke blanketed the marina and continued for some time. The engine was running well, and the smoke level diminished in a few minutes, but it got everyones's attention, and not in a good way.
I realized that’s what we lived with for the first 50+ years of the outboard engine. With the advent of the clean direct-injected two-strokes, and current four-stroke engines, startup smoke has disappeared, fuel consumption has decreased, and running quality has improved dramatically. Like many advantages we have today, we kind of take the current crop of smooth, clean running outboards for granted.
While few of us may know what the emissions numbers were, and have dropped to, it’s evident from the lack of visible smoke, lower fuel consumption, and greatly improved running quality that many engineers have done their homework. Just for comparison, a typical 15 year-old large outboard engine may produce 120 – 160 grams-per-kilowatt-hour of hydrocarbon (HC) and nitrogen oxide (NOx) emissions. Currently, clean two-strokes (direct-injected) and the large four-strokes have reduced emissions to somewhere in the 12 – 25 gpkh range. Obviously, there has been significant work done. This effort was not easy, and not without significant cost. The engines today may be higher in price, but deliver the kind of power and quality we expect.
In 2008, the federal EPA requirement will go to “Three- Star” rating for a fleet average of about 16 gpkh. As in cars, with fleet averaging there is room for some to be above that level, and others may fall below. The average of a builder’s production of all horsepower models is what must satisfy the EPA to get the Three-Star certification. You’ve all seen the “Star” rating stickers on the rear of all outboards—there are One, Two, and Three-Star ratings, with Three being the most stringent, and resulting in the lowest emission levels for the most environmentally clean product. Many smaller engines are actually higher in emissions than the larger ones.
The use of catalytic converters on inboards and sterndrives has caused many people to wonder whether outboards will see mandatory catalytic converters as well. The sterndrive and inboard emission levels for engines below 500 hp with catalytic converters is proposed to be 5 gpkh of HC and NOx! That’s a large reduction from the engines we’ve lived with. Sterndrive and inboard engines over 500 hp will have to conform to a different set of rules, since it requires a lot of fuel to make that kind of power and it isn’t practical to try to reduce those big engines to the same emission level. You start burning things up (or down) when you try to run an engine with high loads and lean mixtures. Emissions of NOx go up when you just try to run leaner mixtures. It’s not easy to build compliant engines, and it’s been in discussion for many years to get the industry to this level of understanding.
Will outboards require catalytic converters and will emissions levels continue to be lowered? The answers are, “we hope not, but probably,” and “yes.” In the next decade, or so, California, and subsequently the EPA, will likely demand emissions levels that can only be met through the use of catalytic converters.
The good news is the clean two-strokes will likely be around for a good long time. The manufacturers are working hard on the next generation of power, while planning to meet emissions levels of the future. By 2009-2010 all outboard manufacturers must get their emissions down to the levels that California requires today (Three-Star).
This effort will likely continue to drive the products we are offered, and in most cases we will all have better products, continued great performance, and lower emissions too.
E-mail Tom directly with questions or comments at tom.ireland@centerconsoleangler.com.