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In a message dated 9/23/2003 7:48:32 AM Eastern Daylight Time, eanderson@carolina.rr.com writes:
First, I absolutely agree, Al that the increased in power that would move my static rpm from 5200 to 5800 rpm on a cold day, could of only had a small contribution from the colder denser air. Once, I eliminated a possible tach malfunction at high rpm, that increased power puzzle is part of what got me started on this DIE analysis. It is now clear to me how and why that additional power was there on cold days, but not on the warmer days. In fact,
in my presentation in October at Shady Bend, I use that the equations to explain exactly how and why that was happening to my engine.
Is not the improved performance from the colder intake air, the reverse of the poor performance we look for when we check the carb heat? If you supply hot air to the inlet without adjusting the mixture, (already ideal for the colder intake air), that makes for a lowered volume of oxygen for nearly a constant supply of fuel. At least on carburetted engines, this is driving the mixture way rich, and lowering the total oxygen available. Thus lowered RPM, and poor performance. But with or without the corrected mixture of an injection system, less total oxygen means poorer performance. Not an anomaly. An expected outcome.
The rotary, when equipped with a powerful ignition system, will run way over rich as well as way over lean. Best power is at 1565 degrees EGT. This is well on the rich side of peak EGT, as that can be over 1700 degrees. The engine will seem to be running just fine. No miss firing at all. You need at least an EGT probe in each exhaust header. In the air just the RPM is all you need. Best power mixture is the same place and time as best RPM.
Lynn E. Hanover
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