490" Supercharged FE, A/F Rich

Air/Fuel ratios are important on any engine, but on a supercharged or turbocharged engine they are critical. Normally these engines should be run richer than an equivalent naturally aspirated engine, to give some protection against detonation. The graph at right shows the dyno results from a 490" supercharged FE, which was basically the upgraded version of the previously described 489" supercharged engine. The horsepower curve appears headed for 1100+ HP when the power output starts fluxuating at 5200 RPM. A/F appeared a little rich, but not significantly, masking the problem somewhat. In addition, these values were consistent across the RPM band, and the engine seemed to run fine below 5000 RPM, steering us away from A/F as the problem. Jetting down didn't have a significant effect on these values, which was also confusing. As a result the engine was taken off the dyno without resolving this problem.

Later after the engine was installed in the car, the carb was finally jetted down and we got good results at the track. After the racing season, the engine was re-run on the dyno and made just over 1200 horsepower.

490" Supercharged A/F Too Rich