The Effect of Injection Timing on the Performance of Natural Gas with a High Carbon Dioxide (CO2) Content in a Direct Injection (DI) Gas EngineAyandotun B. Wasiu, A. Rashid A. Aziz and Morgan R. HeikalMATEC Web of Conferences, 13 (2014) 02027DOI: https://doi.org/10.1051/matecconf/20141302027