Back doing bits on the FZR. I decided to change the plenum inlet from the small tube and to mount a flange. To the flange I am able to mount a throttle body if/when I get around to it, or as in the photos just fit an airfilter for when I run it normally aspirated like now. This adaptor is 3D printed PETG and seems pretty tough. The inside steps down with a similar shape as the entry on Mikuni carbs. The outside is shaped to allow the fitting of the cap screws used to mount it.
In the future I want to try a single throttle body between the turbo and the plenum and I've been putting a bit of thought into the design. The way it is usually done with a disc mounted on a shaft has always looked like a quick and dirty way of doing it to me. I don't like the screws in the intake though I understand they very very seldom cause problems. The shaft with screw holes in it is also a weak link in my opinion. V-rods can have issues with the shafts for instance. Some sort of a slide valve was considered but I think stiction might be an issue and having it slide on rollers increases complexity too much. A ball valve has a few downsides for me as well. What I have thought of is having a shaft with a disc but made as one piece which would allow it to be aerodynamically shaped and also hopefully completely reliable. This would of course require a 2 piece throttle body which would simply be 2 pieces with a hole bored down the middle and a couple of holes for the shaft to pivot in. I really can't see why this hasn't been done before. Maybe I just haven't seen it.
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