Compression

Are you starting the dyno run at these rpm’s?
No. That's probably close to the idle speed depending on the rest of the combination. Dyno sweeps are done at full load wide open throttle. I don't think this engine would be used under those conditions at that rpm. I will use the dyno to tune the strongest stable idle I can. I can load the engine to simulate acceleration from a stop sign or load then quickly return to idle too see how stable the engine is when it returns to idle. I can look at o2's, engine vacuum, engine speed, load, timing, egts and etc. To help help sort it out. It can give a good starting point that may require additional tuning when driven on the street or sometimes little or no additional tuning is required.