Quote:
Originally Posted by Frank Lee
And I wish cylinder deactivation was more effective.
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It is effective. 6.2L Chevy engines with it get fairly good mpg. I shudder to think of how much fuel those would burn with all 8 cylinders running at idle.
Back to OP, Honda went for cylinder deactivation because it already has variable timing. The benefit is additive, but you add mechanical complexity.
Lean burn from the factory is not possible with emissions regulations, but we can always trick the ECU with aftermarket parts, and this is the only cost effective pumping loss reduction a DIYer can do unless they were already modifying other parts of the engine for unrelated reasons. Well, I guess a hot air intake works too, but I would worry about the engine knocking from that.
The way you do DIY lean burn is to not be greedy and only go up to 1.1-1.15 lambda using a wideband sensor and narrowband emulator, then richen the fuel map in appropriate areas so it's running at the correct fueling when under load. On the FR-S, before I went on the freeway and triggered the ECU to start correcting the mix, I dropped the idle fuel flow rate 10% by going 15% lean, which is rather incredible. I was able to pick up 1mpg on the freeway by moving the intake cam further, but that was probably not worth the effort.