I was mounting a new filter and velocity stack on my .82 this morning and decided to do a before and after test. The fiter is a BruLine and the stack/carb gap was filled with a green automotive air conditioner o-ring that didn't protrude into the air flow hardly at all. The fuel is 15% Omega and the prop is an APC 14x4W. The tank was a 2 ouncer. No linkage was attached to the throttle and the spring held it full open. Here's the results:
No stack/filter: Peak 10,050 richened to 9,650 for the test run. Run time to empty was 2 min. 30 sec.
With stack/filter: Peak 9660, ran at 9360, and the run time was 3 min., 20 sec.
No spitting from the carb was observed before the stack/filter was added.