[Dimman]

Originally Posted by serialk11r

I did, and I asked arghx7 about it, and he confirmed my suspicions. Direct injection simply needs some sort of charge motion to get it working well, port injectors are less picky since you can just vaporize the fuel on the valve. The port injectors aren't supposed to run big duty cycles though, so that suggests they still needed to design some degree of tumble flow into the ports, however that works.

The paper didn't say D4-S was to break the compromise, rather it described the flow compromise that a DI engine sees, the efficiency disadvantage that port injection has, and then they went on and talked about their new engine, without actually saying what they did to the ports.

They didn't do anything to them. Basically they were normal without SCVs choking them and the cutouts that increase tumble in the 3GRFSE.

The purpose of the Yamaha developed double fan spray pattern is

to promote a homogeneous mixture at lower engine speeds without any devices to generate intense air motion to improve combustion stability.

With the developed spray, this test engine can improve at all engine speeds even though tumble is weaker without a SCV.