This thread didn't die, and I'm still getting foam flecked PM's from t vago, so I want to try delving back into whether or not DCD will improve FE.
But I want to try simplifying my argument again, largely for previously mentioned reasons.
So, here goes:
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DCD vs lean-burn: Why does lean-burn work and DCD not?
Suppose the lean-burn engine is operating at 25% (er, how to say this?) leanness, by which I mean stoichiometric AFR X 1.25.
Compare to DCD with 25% of cylinders deactivated, 75% at stoichiometric AFR. All else being equal, including valve timing.
If you think I'm wrong, explain to me:
- Is there a difference in air mass flow rate?
- Is there a difference in manifold vacuum?
- Whatever else you think requires consideration.