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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 onto the intake valves and then pulled into the combustion chamber during the intake stroke. Components of the fuel are unstable in this environment and form deposits on the upstream face of the intake valve. 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). Established standards are available to measure the propensity of IVD formation, for example the ASTM D6201 engine test and ASTM D5500 vehicle test.

Piston ring and liner wear measurements and analyses were performed in a production 3.6L V6 gasoline engine with radiolabelled engine parts. Three isotopes were generated: one in the engine liner using surface layer activation; one each in the top ring face and top ring side using bulk activation. Real-time wear measurements and subsequent rates of these three surfaces were captured using the radioactive decay of the isotopes into the engine oiling system. In addition, surface roughness and wear profile measurements were carried out using white light interferometry. The results from Phase I provided insights on evolution of wear and wear rates in critical engine components in a gasoline engine. Phase II will extend this work further and focus on evaluating the fuel additive effects on engine wear.

Particulate mass (PM) emissions from DISI engines can be reduced via fuels additive technology that facilitates injector deposit clean-up. A significant drawback of DISI engines is that they can have higher particulate matter emissions than PFI gasoline engines. Soot formation in general is dependent on the air-fuel ratio, combustion chamber temperature and the chemical structure and thermo-physical properties of the fuel. In this regard, PM emissions and DISI injector deposit clean-up were studied in three identical high sales-volume vehicles. The tests compared the effects of a fuel (Fuel A) containing a market generic additive at lowest additive concentration (LAC) against a fuel formulated with a novel additive technology (Fuel B). The fuels compared had an anti-knock index value of 87 containing up to 10% ethanol. The vehicles were run on Fuel A for 20,000 miles followed by 5,000 miles on Fuel B using a chassis dynamometer.

This work compared the piston deposit ratings in an engine when it was run on gasoline with a high concentration of deposit control additive (DCA) versus gasoline with a low concentration of additive. The additives came from different sources and contained detergents with different functional groups. The engine was a Ford V-8 PFI engine, which is used in ASTM D6593, the Sequence VG test. The experimental procedure followed the ASTM protocol, except for the fuel, which was treated with additives. Deposit ratings were better, at 95% confidence, in the tests using a high concentration of additive versus the tests using a low concentration.