After completion of the XO-121 development (12:1 compression ratio for a tractor engine) and additional studies by Ethyl Corporation, development was continued on Oliver’s family of gasoline engines. An important objective was to improve power and economy through better utilization of fuel qualities by finding optimum design combinations for current and projected fuels.
Using the XO-121 type combustion chamber, a modified Super 88 engine was tested at various compression ratios and the results compared to those obtained for the XO-121. It became evident that there were many areas requiring further development, including combustion chamber configuration, spark plug location, manifolding, camshaft and valve timing.
A series of tests was conducted, taking one item at a time. Evaluation and comparison of the results of these tests constituted a well-integrated, long-range development program. Results of this long-range program were very rewarding, as evidenced by the Nebraska test results of the Oliver 1800 tractor with this new gasoline engine.