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High Ethanol Fuel Endurance Advanced Engineering Project

High Ethanol Fuel Endurance Advanced Engineering Project. A study of the effects of running 15% ethanol concentration in current production 4-stroke engines and “legacy” 2-stroke engines. Prepared By: Dave Hilbert. Overview.

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High Ethanol Fuel Endurance Advanced Engineering Project

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  1. High Ethanol Fuel Endurance Advanced Engineering Project A study of the effects of running 15% ethanol concentration in current production 4-stroke engines and “legacy” 2-stroke engines. Prepared By: Dave Hilbert

  2. Overview This project is a cooperative effort to assess the feasibility of increasing the allowable ethanol concentration in gasoline above the current legal limit of 10% for use in marine engines. • Objectives of this project: • Run 300 hours of wide-open throttle endurance on 3 engine families and measure emissions at 0, 150, and 300 hours. • 9.9HP 4-stroke carbureted, 200HP 2.5L 2-stroke EFI (represents “legacy” product) and 300HP L6SC Verado engines were chosen. • Two engines from each family • Test engine operated on E15 • Control engine run on pure gasoline

  3. Test Engine Specifications

  4. Results Summary • Verado • Initial E15 engine generated HC+NOx emissions in excess of FEL when operated on E15 fuel. • E15 engine failed exhaust valves. Metlab analysis showed excessive metal temperatures caused a reduction in fatigue strength. • F9.9HP • The E15 engine on E15 fuel showed high HC variability at the post-endurance emissions testing. It is believed that this engine was misfiring at idle due to the lean operation. • The E15 engine showed evidence of hotter metal temperatures due to carbon deposits, etc. • The E15 engine showed signs of gasket deterioration on the fuel pump. • 200HP EFI 2.5L 2 Stroke • E15 engine showed no difference in emission deterioration. • E15 engine failed the rod bearing. Root cause is indeterminate due to the degree of damage. • How does ethanol affect oil dispersion in two stroke engines? • Other than the bearing failure, the end of test teardown and inspection did not show any significant difference between the 2 engines

  5. Results Summary-Continued • 4.3L V6 ECT Mercruiser • Two emissions tests were performed on a 4.3L catalyzed sterndrive engine to compare the E0 fuel and the E15 fuel. No durability testing was completed on the 4.3L engine with E15 fuel. • This testing was not part of the contract, but was performed due to the fact that the E15 test fuel and a catalyzed engine were readily available on the dyno. Also, it compliments the testing on a 4.3L carbureted engine done by Volvo Penta. • EGT increased ~20C and catalyst temperatures increased ~32C at Mode 1 (WOT). • Valvetrain durability and catalyst system deterioration concerns. • Fuel consumption increased by ~5% (mass-based fuel flow) in closed loop operation. • Aside from HC and CO reductions at Mode 1 (open loop), the E15 fuel afforded no real benefit to reduced emissions overall. • NOx increased at Mode 1, but not as much as HC decreased for a slight overall reduction. • HC, NOx and CO in closed loop operation are essentially unchanged between the 2 fuels. • Overall • The CO emissions were lower on all engines with E15 fuel due to leaner running (as would be expected). • Fuel analysis showed the E15 fuel that was used in testing was in line with expectations.

  6. Conclusions and Recommendations Summary • Despite the limited scope of project several significant issues were discovered. • Durability Failures • Emissions Issues (elevated NOx, HC variability) • Run Quality due to Lean Operation • More testing is necessary to understand effects on: • Driveability- Ex. cold and hot start, transient accel/decel, “boiloff”, etc. • Oil dispersion in 2 stroke engines • Storage (phase separation, corrosion, etc.) • Test program was a cursory look at the effects of E15. • Sample size was insufficient to have statistical significance. • WOT operation only-masks effects of true customer duty cycle

  7. Fuel Comparison

  8. Fuel Comparison

  9. Variability on E15 Engine is a concern. “E15 fuel-zero hour” and “EEE-E0 fuel 150 hour” checks are likely due to run-to-run variability. “E15 fuel-300 hour” variability is due primarily from Mode 5 (idle) HC emissions. Trends on EEE-E0 fuel are consistent between the 2 engines. F9.9HP 4-Stroke Emissions

  10. Both engines had a tendency to run leaner at Modes 4 and 5 with increasing endurance time. The combination of the inherent leaner operation and the E15 fuel was enough to cause misfires/poor combustion at idle. The misfires caused the HC emissions to increase and become highly variable. RICH LEAN F9.9HP 4-Stroke Emissions

  11. The fact that the E15 fuel emissions tests show that HC emissions increase with leaner mixtures supports the misfire theory. The graph below shows HC vs. equivalence ratio at idle for every emissions test performed on engine 0R352904, which is the “E15 engine”. All E15 fuel emissions tests are shown in red All EEE-E0 fuel emissions test are shown in blue F9.9HP 4-Stroke Emissions

  12. F9.9HP 4-Stroke Teardown and Inspection • More carbon deposits on intake valves of E15 engine.

  13. F9.9HP 4-Stroke Teardown and Inspection • More carbon deposits on intake port of E15 engine. E0 E15

  14. F9.9HP 4-Stroke Teardown and Inspection • More carbon deposits on piston undercrown and rods of E15 engine.

  15. F9.9HP 4-Stroke Teardown and Inspection • The gasket showed signs of deterioration on the E15 engine compared with the E0 engine. • The gasket on the E15 engine had a pronounced ridge formed in the area that “hinges” when the check valve is in operation • The E15 gasket material in the area that seals the check valve also had signs of wear that were more advanced than the E0 gasket. E15 E0

  16. F9.9HP 4-Stroke Teardown and Inspection • Material transfer from gasket to diaphragm in mechanical fuel pump. E15 E0

  17. Verado Testing Summary / Review • Verado E15 Engine: • Initial emissions tests on E15 fuel generated HC+NOx values in excess of the FEL set for this engine. • Three-run average on E15 fuel: HC+NOx = 25.6 g/kw-hr • FEL set to 22.0 g/kw-hr • E15 engine failed the exhaust valves. • High cycle fatigue due to elevated temperatures

  18. Verado E15 Valve Failure Investigation Cylinder 3 Bottom Valve Cylinder 3 Top Valve Cylinder 6 Top Valve

  19. Verado E15 Valve Failure Investigation Cylinder 3 Bottom Valve

  20. Verado E15 Valve Failure Investigation • The failed valves were checked for hardness and the values were low. • Valves from other E0 engines w/o failed valves were measured and the hardness values were within expected values. • Brand new valves were also measured for comparison.

  21. Verado E15 Valve Failure Investigation • The new valves that were hardness checked were then oven-aged for 24 hours and the hardness was checked again. • A simple linear interpolation would indicate the E0 valve temperature was around 780°C and the E15 valve temperature was approx. 890°C or higher. • The measured change in exhaust gas temperature was only 25-30°C.

  22. 200HP EFI 2.5L Two-Stroke Testing • There was more variability in HC+NOx on the E0 engine than any of the changes on the E15 engine. • The trend of CO emissions change vs. endurance time was similar between the 2 engines. • The rod bearing failure on the E15 engine prevented completing the testing. • Due to the extensive damage, the cause of the bearing failure could not be definitively determined. • Assembly error causing a step at the rod / cap interface? • If so, why did it run 250+ hours of WOT? • What effects would the ethanol have on oil dispersion?

  23. 200HP EFI 2.5L Two-Stroke Emissions

  24. Root cause of bearing failure is unknown. 283 total engine hours, 256 WOT endurance hours No rollers were recovered. 200HP EFI E15 Engine-Bearing Failure Remaining Pieces from Cyl 3 Rod Bearing Cage Undamaged Bearing Undamaged Rod Rod from Cyl 3

  25. Additional Testing-4.3L V6 ECT Fuel Comparison • Increase in EGT of 20°C, increase in catalyst temperature of 32°C at Mode 1. • No appreciable difference in emissions during closed loop operation. • Changes in HC and CO at Mode 1 are expected due to lean operation. • “The increase in catalyst temperature at WOT will cause more rapid deterioration of the catalyst system leading to higher exhaust emissions over the lifetime of the engine.” • Increase in fuel consumption (mass basis) of ~5% in closed-loop operation.

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