Displacement on demand

[NoDOHC]

Originally Posted by libor

How is the driveability with such lean mixture?

Honestly, I have adapted to drive the car with the lean mixture - therefore I consider it to be fine. most of my friends consider the car to be 'undriveable'. As long as I hold the throttle at a consistent position while cruising and don't mind some hesitation if I get into it to pass someone, it drives fine.

Originally Posted by libor

There is interesting discussion over rx8club about negative split and lean burn during cruising but concensus backed by injector duty and actual gas mileage is, that best gas mileage, driveability and overal responsiveness is best with slightly rich mixture 0.92 - 0.93 Lambda. And this is with high CR, no overlap engine.

I have 9.2:1 polished rotors (originally 9.4:1) and no overlap (or only stock overlap - like 8 degrees).
.93 L gives better throttle response - hands down, but my research has shown the engine to use considerably less fuel at stoic. than at 0.93L and slightly better mileage at 1.1 L than at stoic.

Originally Posted by libor

I agree with you that conventional rotary engine very same like piston engine has highest thermal efficiency at around 1.15 Lambda? But this is measured at WOT and practical parameters mentioned above aren´t investigated.

The efficiency difference is higher at partial throttles because the BMEP is lower, thus the throttle must be more open (lower vacuum). This contributes to better efficiency.

Originally Posted by libor

You should try it

I have

I have datalogs of the same stretch of road on the same day at the same speed while varying ignition timing, fueling and ignition spilt. I then used Excel to average the injection time and determine the average fuel economy (for that stretch of road) obtained at each setting. I probably drove that stretch of road 30 times in one evening.