BLUE TII

iTrader: (9)

The AFR read at the exhaust pipe is the waste gasses of all the chamber, not just the parts that contributed to combustion.


Lambda sensors work by measuring the amount of remaining oxygen in the tailpipe.

It seems to me under high load the fuel injected into a rotary either burns to support combustion or much of it burns externally in the manifold before it gets to the O2 sensor and in the case of a dyno with exhaust clamp before it reaches the end of the exhaust system.

We have external combustion as well as internal as we have an exhaust port that never closes.

I am saying the poor combustion chamber design means more of the fuel is burned after the power stroke and did not support the power stroke and that is why I say I believe the rotary needs to run "richer" than a more efficient piston engine.


If you have bad cycles the mixture will read leaner than it should rather than richer.

I wasn't trying to relate AFRs to misfires.

I am saying I believe people make power leaning the turbo rotary out because it is taxing the ignition system less and so less misfires.

I didn't try to relate that to AFRs except to note that people are thinking they are leaning it closer to "max power" AFR and I believe they are simply eliminating misfires.

Why did Mazda put such a high performance ignition on say a S4 NA so that enthusiasts use the same system on turbo cars with 4x the power and "high" boost? Likely to prevent misfires that will raise EGTs under load, dump O2 and fuel into the cat to burn when not under load and so kill the 3 cats which they had to warranty for 10 years.

What did foreign market S4 NA have where they did not have to warranty the cats?

A distributor.

Liborek

This is where gas analyzer would shine. Gas composition will be very different between constant volume process around TDC and burning towards exhaust stroke.

Majority of air/fuel is burned during power stroke, but burn rate is so slow and so late, that very little can make power as peak leverage is much earlier and gas is already expanded. Most energy goes out of the exhaust

Rich AFR can be just matter of safety for some people, and it really is, up to the point of course. 0.7 Lambda certainly doesn´t give most power on given airflow, but it allows highest knock limited power, at least on gasoline.