(Edited spelling, highlights added):
"High Ethanol Fuel Endurance:
AStudy of the Effects of Running Gasoline with 15% Ethanol Concentration inCurrent Production Outboard Four-Stroke Engines and Conventional Two-StrokeOutboard Marine Engines"
Report by David Hilbert MercuryMarine Fond du Lac, Wisconsin
NREL is a national laboratory of the U.S. Department ofEnergy, Office of Energy Efficiency & Renewable Energy, operated by theAlliance for Sustainable Energy, LLC.
Copied from nrel.gov docs/fy12osti/52909.pdf on 11/27/2011.
Pg. 50 of 52:
Summary of Results:
EPA’s recent announcement of a partial waiver approving E15fuel for use in 2001 and newer cars and light truckswill create an opportunity for consumers to misfuel theirmarine engines. This program indicates that misfueling currently availablemarine outboard engines may cause a variety of issues for outboard engineowners. These issues include driveability, materials compatibility, increasedemissions, and long-term durability. There were also 2 examples of how theethanol fuel caused an increase in fuel consumption.
9.9HP Carbureted Four-Stroke:
The E15 engine showed high variability in HC emissions atidle during the emissions tests at the end of the 300 hour endurance period.Both the E0 control engine and E15 test engine ran leaner at idle and low speedat the end of the endurance test. When operated on E15 fuel after 300 hours ofendurance, the lean operation at idle coupled with the additional enleanmentfrom the E15 fuel caused the engine to exhibitmisfire and poor run quality (intermittent misfire or partial combustionevents). A misfiring engine would cause customer dissatisfaction due tothe inability to idle the engine properly,excessive shaking, and hesitation or possibly stalling upon acceleration.As it relates to this study, the misfire caused an increase in HC emissions atidle. This increase in HC variability at idle caused the average total HC + NOxto increase from the start to end of endurance, whereas the HC+ NOx on E0 fuelon both engines showed a decreasing trend. As expected, the CO emissions werereduced when using E15 fuel due to the leaner operation.
The power and torque output of the E15 engine was higherwith E15 fuel than with E0 fuel. The power and torque output of the E0 controlengine increased slightly with more endurance time. The power and torque outputof the E15 test engine showed a flat or declining trend with more endurancetime.
The end of test inspection showed evidence of elevated temperatures on base enginecomponents due to the lean running onE15 fuel. There were significantly more carbon deposits on several componentsof the E15 engine, indicating that these parts likely had higher metaltemperatures during operation. Hardness measurements indicated that the pistonshad higher operating temperatures on the E15 engine. The exhaust gastemperature increased 17°C at wide open throttle as a result of the leaneroperation on E15 fuel.
The fuel pump gasket on the E15 enginealso showed signs of deterioration compared with the E0 engine after approximately 2 months of exposure to E15fuel.
300HP Four-Stroke SuperchargedVerado:
The E15 Verado failed 3exhaust valves prior to completion of the endurance test. One valvecompletely failed and 2 others had developed significant cracks. Metallurgical analysis showed thatthe valves developed high cycle fatigue cracks due to excessive metaltemperatures. The majority of exhaust valves on the E15 engine lost asignificant amount of lash which may have contributed to the observed valvefailures. The exhaust gas temperature increased 25-30°C at wide open throttledue to the lean operation with E15 fuel.
In addition to the elevated temperatures on the exhaustvalves, the pistons showed evidence of higher operating temperatures. Thecarbon deposit differences indicated that the E15 engine’s pistons were hotterduring operation. (Note: This Mercury report summary was posted on November27th, 2011 and thereafter by Fuel-Testers Company, on their websites fuel test kitdot com and http://www. fuel-testers .com.+ forum message board: fueltesters. website toolbox.com -If you find this exact report on any other website, that includes thisnote without giving full credit to Fuel-testers for supplying the reportinformation, the site you are at is guilty of plagiarism and/or copyrightinfringement - Fuel Testers company invests a tremendous amount of time andexpense educating the public on ethanol; At the very least the website you areon should indicate they copied this post (and obviously without reading orediting or this note would have been removed). Please notify us of this, email fueltesters at yahoo dot com. Thank you. Report continues here). The E15 Veradogenerated HC + NOx values in excess of the Family Emissions Limit when operatedon E15 fuel, but did not exceed the limit when operated on EEE-E0. The primarycontributor to the increase in exhaust emissions was the NOx due to enleanmentcaused by the oxygenated fuel. The CO emissions were reduced when using E15fuel due to the leaner operation, as expected.
At emissions mode point 3, the lean combustion due to theE15 fuel caused the engine to lose torque output due to operation significantlyleaner than LBT. As a result of the torque loss, the throttle input had to beincreased 10% to maintain the same torque output as on E0-EEE fuel. The changein throttle input caused an increase in fuel flow of 10%. Mode 3 isrepresentative of a typical cruising speed and load. The E15 fuel would causethe fuel consumption to be 10% higher at that operating point for a customer.
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200HP EFI 2.5L Two-Stroke:
The 200HP EFI two-stroke engine showed no signs of exhaustemissions deterioration, though the emissions output after the full endurance testing was not measured due to afailure of the E15 engine. The primary driver of the HC + NOx emissionson this engine family was HC (approximately 98% of the HC + NOx total). Asexpected, since the E15 fuel caused the engine to run lean, the HC emissionswere lower, as were the CO emissions. There was more variability of HC + NOxobserved on the E0 engine than the change in emissions on the E15 engine. Thedeterioration of the CO emissions had similar trends between the 2 engines.
The endurance test of the E15 engine was stopped short ofthe 300 hour target due to a connecting rodbearing failure on cylinder 3. The root cause of the bearing failurecould not be identified. More testing is necessary to understand the effects ofethanol on two-stroke engine lubrication mechanisms where the oil and fuel movetogether through the crankcase. The E0 enginecompleted the entire 300 hours of durability testing.
Other than the bearing failure, the end of test teardown andinspection did not show any visible significant difference between the 2engines. Hardness checks performed on the pistons of both engines indicate thatthe E15 engine may have had higher piston temperatures, a concern on two-strokeengines where higher temperatures could lead to more power cylinder failures.The exhaust gas temperature increased 15-20°C on average due to the leanoperation with E15 fuel.
4.3L V6 EFI Four-Stroke CatalyzedSterndrive
Since E15 fuel was readily available in the test facilityand an engine equipped with exhaust catalysts was on the dynamometer, emissionstests were conducted on a 4.3L V6 sterndrive engine. No durability testing wasperformed. At rated speed and wide open throttle the exhaust gas temperaturesincreased by 20°C on average and the catalyst temperatures increased by 30°C. Thisincrease in catalyst temperature would likely cause more rapid aging anddeterioration of the catalyst system at WOT. The overall effect of the increasein deterioration rate would be duty cycle dependent. The HC and CO valuesdecreased at the Mode 1 (rated speed, rated power) emissions test point, whichis an open loop operating point, due to leaner operation with E15 fuel, asexpected. The fuel consumption increased by 4.5% at the operating points thatwere running in closed-loop fuel control.
This test program was limited in scope in terms of operatingconditions. More investigation is necessary to understand the effects over abroader range of conditions. Ethanol’s effects on part load operation, coldstart, hot restart/vapor lock, and overall driveability need to be evaluated.The wide range of technology available for marine engines due to the wide rangeof engine size will complicate this issue significantly. Mercury Marineproduces engines from 2.5HP-1350HP with a wide array of technologies rangingfrom two-stroke or four-stroke; carbureted, EFI, or direct fuel injected;naturally aspirated, supercharged, or turbocharged; and more.
Ethanol’s ability to absorb water intothe fuel is of paramount concern for the marine market and this issue has notbeen addressed in this test program. The contaminants that water can bring withit, potentially saltwater, can cause severe corrosion in fuel systems. A leakor fuel system failure could cause the engine to be inoperable and leave thevessel stranded, which would obviously be a major dissatisfaction to thecustomer. In addition, a better understanding of the effects higher ethanolblends have on marine fuel systems in terms of materials compatibility andcorrosion is needed. Marine vessels tend to have very long storage durations, canbe stored in very humid environments, and will have more opportunities to havefuel system exposure to water, including saltwater.
More testing is needed to understand how ethanol blendsaffect oil dispersion in two-stroke engines that have fuel and oil movingthrough the crankcase together. Ethanol tends to be a good solvent and maybreak down lubrication at critical interfaces by cleansing these surfaces ofthe residual oil film.
4.3L V6 Catalyst Sterndrive EmissionsComparison EEE vs. E15 Fuels
Figure 51: Emissions Comparison 4.3LV6 Catalyst Sterndrive, EEE vs. E15
(See report forchart and more information).
The entire report can be viewed atNREL.gov website;
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