The Influence of Residual Gases on Knock in Turbocharged SI-Engines 2000-01-2840
In this investigation the influence on knock from the residual gas in the cylinder is investigated. Gas was sampled from inside the cylinder prior to ignition, the Residual Gas Fraction, RGF, was determined and the Knock Intensity, KI, was measured. By altering the exhaust backpressure the RGF was changed. By measuring the knock intensity for different RGF the influence on knock from residual gas was investigated.
It is shown that with increased residual gas fraction the knock propensity of the engine is increased, and subsequently, decreased RGF gives lower knock intensity. This is showed by the fact that, with maintained knock intensity at 30 kPa, the ignition timing can be advanced as much as 5 Crank Angle Degrees, CAD, if the RGF is reduced with 15%.
Fredrik Westin, Börje Grandin, Hans-Erik Ångström
Royal Institute of Technology
International Fuels & Lubricants Meeting & Exposition
Design of Racing and High-Performance Engines 1998-2003-PT-100, Combustion and Emissions Formation in SI and Diesel Engines-SP-1562, SAE 2000 Transactions Journal of Fuels and Lubricants-V109-4