why is the dynamic chamber shaped the way it is? (like a bathtub)
 

I was just wondering why the surge tank/dynamic chamber is shaped how it is on the series 4 motors.. The the paths that go to the secondary runners are ok, but the ones that go to the primaries are horrible! from the TB, it just kind of dead ends into a large chamber, then goes out the two small ports at the bottom. It looks like something that was meant to muffle sound, not flow air. I was wondering if it serves a puirpose, and if so, what? If it doesn't serve a purpose, i think I may fill the majority of it in, just leaving a smooth path from tb to primary ports. Anyone know? Is the dynamic chamber on the series 5 the same/similar? Thanks,


~Jesse

The idea on the series 4 motors was to create a superchanging effect, by the runners.

As one rotors intake port closed, it started to pressurise the combustion chamber, forcing the part of the intake charge back out of the cumbustion chamber just before the chamber sealed.

This forced out intake charge was supposed to back charge the intake change going into the second rotor. Which in-turn, did the same thing back charging the first rotor as its intake closed to the combustion chamber.

Yamaha did a lot of work on that chamber and intake runners for Mazda, to bring up the power on the 13b almost 10 HP and about 8ft/lbs from earlier 13B fuel injected motors.

Well, you say its "supposed" to help, but wouldn't it help more if it was just a straight shot into the extension manifold? That would increase the speed of the air moving through, so more low end torque... or so I'm theorizing... could it be done, has it been done, and what were the results?

Thanks Icemark,

~Jesse