[serialk11r]

What do you mean by 40:1? Is that for stratified charge?
Also the 15:1 to 20:1 you mentioned, you said that was "during intake stroke". But I'm fairly sure they need to hit stoichiometric for emissions, so you mean that they supplement that in the compression stroke right?

I remember someone posted a link to an article about the D4S system on the GR engines, and I remember it mentioned they do not use stratified charge because the NOx levels were too high. That article mentioned that the principal advantage to D4S was that they were able to create nearly homogeneous mixtures, while port injection and direct injection alone are not able to. They had some charts showing how there was more fuel in certain areas of the cylinder with only one injector operating, but with both they were able to get it pretty close to homogeneous.

I still am not too sure why that Lexus article says the direct injector fires only during intake stroke for everything but cold start, I'd think that during the compression stroke it would be better since you can then cram more air in, and also use the cooling effect to directly reduce the energy requirement for charge compression.

EDIT: I also wanted to add, if D4-S works as well as they say it does, then it could be applied to late intake valve closure systems to improve combustion efficiency without the need for low valve lift and the associated throttling loss. In the other thread I mentioned helical cam lobes, and 3d cam lobes, which can be used to control output via late intake valve closure. If a 3d cam lobe or Valvematic type system uses early intake valve closure instead, then it is possible to introduce a bit of restriction at the valve to increase the velocity of the air, but if a 3d cam lobe uses late intake valve closure instead, we can use D4-S to compensate for the lower intake velocity...I am assuming this is going to be how the FR-S engine is going to be able to make the promised 200hp with just one cam profile, if it doesn't have variable lift.