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 BRP has always claimed that E-TEC's offer superior performance
compared to 4-strokes. Their informercial focused on 4-strokes, and many of the
published test results pit the E-TEC against 4-strokes.
Much less has been done comparing E-TECs to other DFI 2-strokes, but tests do
exist. In particular,
Bass and Walleye Boats magazine has done quite a bit
to compare the large E-TECs to Optimaxes and HPDIs.
What are the end results? We think a reasonable conclusion is that for the most
part, current model year engines offer similar performance,
regardless of whether they are 4-stroke or 2-stroke DFI.
There are differences, of course, but they are often not as dramatic as the
manufacturers would have you believe. We've come to the conclusion that
installation, prop selection, boat handling and trim all have a bigger impact
on performance than the differences in technology.
Here are the general differences in performance that we've seen:
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2-Stroke DFI engines (that includes Optimax and HPDI, in addition to E-TEC)
generally exhibit more low-end torque, and would be preferred if you want the
best hole shot, or are running a heavily-loaded boat.
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E-TECs are among the lightest motors for any given HP rating. In the 90 HP
range, for example, they can be over 100 lbs lighter than an equivalent
4-stroke.
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That amount of weight can cause significant trim changes on older skiffs, which
were not designed for motors that heavy. It can also increase the draft of your
boat, if shallow water performance is an issue. Newer skiff hull designs are
usually structured to balance out the higher weights of 4-strokes, although
draft can still be a problem.
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4-stroke engines still offer the absolute best mileage, although the
differential can be fairly small, depending on how you operate your boat.
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EPA certification tests show that E-TECs have emissions levels similar to 4
stroke engines for Hydrocarbons (HC) and Nitrous Oxides (NOx). They are
typically lower in average CO emissions across their RPM range, and appear to
have lower particulate matter emissions, but neither of these types of
pollutants are regulated by the US EPA. (Many thanks to Gary Fooks of the
Eco-Friendly Fishing Association of Australia for correcting us on this point)
However, all of the major brands of engines (2-stroke or 4-stroke) except for
Yamaha's HPDIs and a couple of Mercury Optimax models are CARB 3-star rated, so
they are all pretty clean on regulated emissions.
If you're interested, click
HERE to go to the portion of the EPA website that
contains the certification test data for outboards
We've summarized our observations in the following two sections:
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