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We are interested in learning how commercial intake valve detergents contribute to combustion chamber deposits (CCD) in modern vehicles run for higher mileage. It is appealing to use short mileage (<5,000 miles) tests to evaluate the CCD performance of gasoline. However, the ability to extrapolate CCD performance to higher mileage (≥10,000 miles) is uncertain because of changes in CCD formation processes. For this reason, CCD from base fuel and a commercial IVD detergent package were generated in duplicate 10,000 mile tests using four 1996 model-year vehicles. The detergent package used a polyalkylamine detergent combined with a synthetic carrier fluid and achieved 94% intake valve deposit (IVD) reduction averaged across the four vehicles tested. The CCD weights were found to be variable between repeat tests but, when pooled across the four vehicle fleet, the CCD weights were found to be statistically the same for both the additized fuel and the base fuel.

Comparative testing of pure methanol, methanol/water blends and isooctane in single-cylinder engines has demonstrated that through proper utilization of methanol's fuel-lean combustion characteristics it may be possible to reach CO emissions of the order of 0.1 percent and NOx emission levels of less than 100 ppm in the raw (undiluted) exhaust. Exhaust treatment to remove unburned methanol and partial oxidation products might be required. Concomitant with decreased emissions are specific energy consumption improvements estimated to be in the range of 26 to 45 percent better than achievable with current gasolines and the associated low compression ratio engines and emission control systems. These energy consumption improvements are obtained by virtue of efficient lean operation and by utilizing the high octane values of methanol/water blends at high compression ratios.