Evaluation of Gasoline Additive Packages to Assess their Ability to Clean Up Intake Valve Deposits in Automotive Engines 2019-01-0261
The majority of passenger car and light-duty trucks, especially in North America, operate using port-fuel injection (PFI) engines. In PFI engines, the fuel is injected on the intake valves and this can result in the formation of deposits on those valves as they open towards the hot combustion chamber. These deposits have been found to affect a vehicle’s drivability, emissions and engine performance. Therefore, it is critical for the gasoline to be blended with additives containing detergents capable of removing the harmful intake valve deposits (IVDs).
Even though there are established standard tests to measure the cleanliness of intake valves, to generate data with statistical robustness, it is important to have rigorous testing conducted in a fleet of vehicles, especially the current-generation of vehicles with modern PFI engines. An optimized mileage accumulation protocol was used to assess the performance of new experimental gasoline additive packages in removing the IVDs in a fleet of vehicles typical of engines and vehicles available in the North American vehicle parc. The performance of these gasoline additive packages, both at lower and higher additive treat-rates, was compared to that of a commercial additive package at EPA-approved lowest additive concentration (LAC).
Based on three decades of expertise, the testing protocol was optimized to use fewer vehicles and shorter mileage accumulation than previously required for the same statistical confidence. It was observed that the tested experimental gasoline additive packages demonstrated a statistically higher cleanup at both treat-rates compared to the commercial LAC additive package. This rigorous statistically-robust test protocol can be used to assess candidate fuel additive packages for the North American gasoline market.
Vivek Raja Raj Mohan, Edward Nelson, Jannik Reitz, Jennifer Kensler, Varun Gauba, Matthew Hinojosa, Brent Shoffner
Shell Global Solutions (US) Inc., Southwest Research Institute