MrPotatoHead wrote: ↑08 Jun 2017, 05:35
Hey ringo!
Usually in automotive parts clearances are designed such that when you are up to operating temperature and pressure you have the correct clearances.
Piston to wall clearance is a good example of this.
Turbos typically are designed this way as well.
Now what Honda took into account with their design of the MGU-H I do not know for sure... Perhaps some one screwed up.
Understood. But on a bigger scale; maybe this can be considered clearance as well, the reason i called it a possible issue of design geometry, is because the clearances may well be fine for bearings and shaft,but there is a lot that can be done to manage the expected loads at different running conditions; as i will show with these crude drawings:
here we have the turbo housing with a fixed mounting (i'm not saying this is what honda is doing, but its just hypothetical for demonstration purposes). You can see where the hot turbo expands and pushes against the mounting causing the housing to move upward; and subsequent misalignment.
this other design has two slotted mountings now, but when the turbo expands it pushes outward on the mountings evenly in both directions. this doesn't cause misalignment issues.
keep in mind i'm no expert on this. Just an example of a simple design aspect that addresses the problem on additional loads introduced at high temperatures.
For all we know, this engine could be a science project for some university over there in Japan. Maybe the designers arent considering everything or simply dont have lessons learned from previous experiences.