NEW DELHI: An ARAI report, which recommended roll out of E20, had concluded that using the fuel in E10-compliant vehicles showed deterioration in rubber parts of fuel-system components, such as hoses, gaskets, seals and O-rings. The study — which has not been made public, but has been a reference point for govt and vehicle manufacturers on the issue — had recommended that these parts “may need replacement”.Its findings on the impact of E20 fuel on E10 vehicles also stated that during “4-wheeler engine durability test”, the performance of one BS-IV engine was acceptable with E20, but “issue was observed with BS-VI turbo charged engine after 265 hours of durability”.The part of the study that dealt with “engine durability” stated that two four-wheeler vehicle manufacturers, or OEMs, carried out the test. While for one OEM, no issue was observed for engine durability after 400 hours of testing and performance was acceptable with E20 fuel, in the case of the other OEM, “thermomechanical failure of exhaust valve was observed in the engine(s) tested cumulatively for 809 hours”.A thermomechanical failure occurs when combined stress of extreme heat (thermal) and rapid, repetitive physical movement (mechanical) causes an engine’s exhaust valve to warp, crack, or fracture.People aware of the findings said there could be other reasons for thermomechanical failure of the exhaust valve in case of the second OEM. However, experts involved in vehicle testing said that generally engine durability tests are carried out for 2,000 hours.As per the report, engine durability tests conducted by three two-wheeler manufacturers found no issue, and the “performance is acceptable with E20 fuel”.On all vehicles tested, the study found E20 had no adverse impact on metallic components or the vehicle itself, and the vehicle tailpipe emissions with E20 were within the legislative limits on E10-compatible vehicles.It had also concluded that fuel consumption of vehicles with E20 increased 2-6% compared to E10. However, the percentage increase in fuel consumption varies vehicle to vehicle. The evaporative emissions were also within the legislative limit with E20 and the startability and drivability performance were “ok with E20”.
