There was a House Committee hearing on the unintended consequences of increasing Ethanol in fuel from 10 to 15 percent. I would be willing to bet no one in the news covered this at all. The following is a summary from a report from the National Renewable Energy Laboratory (DOE). Mercury Marine was contracted to conduct these tests, and demonstrates some disturbing effects of E15 fuel. Thes tests were exclusively performed on marine engines, and I hope that similar tests are performed on other outdoor power equipment.
The abridged version of the results are that two of three E15 test engines did not finish the test. All three of the non-ethanol control engines finished with no problems.The two-stroke E15 test engine was damaged so badly that Mercury Marine could not determine the cause of failure.
I feel that this information wasn't given enough attention in the hearing. The two stroke engine that was damaged beyond repair retails for approximately $15,000. Nobody mentioned this at the hearing. More attention was given to the testimonies of the EPA and the various individuals representing the Oil, Gas and Ethanol industries.
Click
here to view the complete report. The Summary follows:
Objective:
The objective of
this work was to understand the effects of running a 15% ethanol blend on
outboard marine engines during 300 hours of wide-open throttle (WOT) endurance
– a typical outboard marine engine durability test. For the three engine
families evaluated, one test engine each was endurance tested on E15 fuel with
emissions tests conducted on both E0 and E15 fuel, while a second control
engine was emissions and endurance tested on E0 fuel for each engine family.
Summary of Results:
Results are based on
a sample population of one engine per test fuel. As such, these results are not
considered statistically significant, but may serve as an indicator of
potential issues. More testing would be required to better understand the
potential effects of E15.
9.9HP Carbureted
Four-Stroke:
• The E15 engine
exhibited variability of HC emissions at idle during end-of-endurance emissions
tests, which was likely caused by lean misfire.
o Both the E0
control engine and E15 test engine ran leaner at idle and low speed operation
at the end of endurance testing compared with operation at the start of the
test.
o The trend of
running lean at idle coupled with the additional enleanment from the E15 fuel
caused the E15 engine to have poor run quality (intermittent misfire or partial
combustion events) when operated on E15 fuel after 300 hours of endurance.
o CO emissions were
reduced when using E15 fuel due to the leaner operation, as expected for this
open-loop controlled engine.
• The E15 engine
exhibited reduced hardness on piston surfaces based on post-test teardown
analysis.
o The exhaust gas
temperature increased 17°C at wide open throttle as a result of the leaner
operation when using E15 fuel. Higher combustion temperatures may have caused
observed piston hardness reductions. Lack of pre-test hardness measurements
prevented a conclusive assessment.
• Several
elastomeric components on the E15 engine showed signs of deterioration compared
with the E0 engine.
o Affected
components were exposed to E15 fuel for approximately 2 months; signs of
deterioration were evident.
300HP Four-Stroke
Supercharged Verado:
• The E15 engine
failed 3 exhaust valves close to the end of the endurance test.
o Metallurgical
analysis showed that the valves developed high cycle fatigue cracks due
excessive metal temperatures.
• The pistons on the
E15 engine showed indications of higher operating temperatures compared to the
E0 engine’s pistons as evidenced by the visual difference in carbon deposits.
• The E15 engine
generated HC+NOx values in excess of the Family Emissions Limit (FEL) when
operated on E15 fuel, but did not exceed that limit when operated on E0
emissions certification fuel.
o The primary
contributor to this increase in exhaust emissions was NOx due to enleanment
caused by the oxygenated fuel.
o CO emissions were
reduced when using E15 fuel due to leaner operation, as expected for this
open-loop controlled engine.
200HP EFI 2.5L
Two-Stroke:
• The 200 EFI
two-stroke engine showed no signs of exhaust emissions deterioration
differences due to the fuel.
o The E15 fuel
caused the engine to run lean resulting in reduced HC and CO emissions. NOx was
of little concern on this type of engine since NOx accounted for less than 2%
of the total regulated HC+NOx emissions.
• The E15 engine
failed a rod bearing at 256 hours of endurance, which prevented completion of
the 300 hour durability test.
o Root cause of the
bearing failure was not determined due to progressive damage.
o More testing would
be necessary to understand the effect of ethanol on oil dispersion and
lubrication in two-stroke engines where the fuel and oil move through the
crankcase together.
4.3L V6 EFI
Four-Stroke Catalyzed Sterndrive:
• Since E15 fuel was
readily available in the test facility and an engine equipped with exhaust
catalysts was on the dynamometer, emissions tests were conducted on a 4.3L V6
sterndrive engine to better understand the immediate impacts of ethanol on this
engine family.
o At rated speed and
load (open-loop fuel control) E15 caused exhaust gas temperatures to increase
by 20°C on average and the catalyst temperatures to increase by about 30°C.
o More rapid aging
of the catalyst system occur due to the elevated catalyst temperature when
considering the high load duty cycle typically experienced by marine engine
applications.
Conclusions and
Recommendations:
Several issues were
discovered in this study from an exhaust emissions and an engine durability
standpoint as a result of running E15 fuel in outboard marine engines. Run
quality concerns were also identified as a result of the lean operation on the
carbureted engine.
Additional
investigation is necessary to more fully understand the observed effects and to
extrapolate them to all types of marine engines over broader operating
conditions. Effects on operation at part load, transient
acceleration/deceleration, cold start, hot restart, and other
driveability-related concerns need to be evaluated. This test program was
mainly testing for end-of-life durability failures, which would not likely be
the first issues experienced by the end users. A customer would likely be affected
by run quality/driveability issues or materials compatibility/corrosion issues
before durability issues. The wide range of technology used in marine engines
due to the wide range of engine output will complicate this issue (Mercury
Marine produces engines from 2.5HP-1350HP).
More testing is
needed to understand how ethanol blends affect lubrication systems in
two-stroke engines that have fuel and oil moving through the crankcase
together. Crankcase oil dispersion is the only mechanism by which two-stroke
engines of this architecture provide lubrication at critical interfaces such as
bearings and cylinder walls. Ethanol may have an effect on the dispersion or
lubricity of the oil.
A better
understanding of how long term storage affects ethanol blends in marine fuel
systems would require more real-world testing. Marine vessels often go through
long periods of storage that could affect the fuel systems given the fact that
the ethanol portion can absorb water when exposed, especially in humid areas
near saltwater.
