Turbo rebuild

[Sonex87AS]

Remote Filter Set Up and Top View - Yes its fuel injected as well as i still have the aero injector inline 2.5 needle if the system has a failure - Works mint : )

[Sonex87AS]

So after careful thought I have decided to not use the Jet Lube and re-design the sealing ring shaft end. I removed the seized sealing ring and polished all parts carefully. I took a solid bronze slug and machined a bearing / bushing / slug call it what you want to take the sealing rings place. The ring originally had about 7 thousand clearances between shaft and housing. My bushing had 3 once completed between shaft and id of the actual bushing. Now I'm not going to get into the nitty gritty of thermal expansion between dissimilar metals ect but alot of thought went into this. I extended the top of the bushing past the secondary tin about 2 thousand to the backside of the exhaust impeller to help seal and prevent the ease of exhaust contaminants from working their way into my creation. Lubrication is still done through splash and carry over from the turbo impeller shaft. This is a press fit and seems to be holding up nicely. Currently i have 7 hours of run time and showing no signs of fatigue or oil blow by. I will continue to monitor and update as engine run time extends.

[bvolcko38]

What about a ceramic bearing?

[Bryan Cotton]

I'm not a turbo guy but the part looks awesome!

[Kai]

What about a ceramic bearing?

I am not convinced that this will solve his problem.

As I understand the issue, luboil is leaking past his shaft seal rings (small piston rings). Some oil will unavoidedly leak past them, driven by the bearing luboil pressure, no matter how good they are or whatever you do. When this oil comes in contact with the white hot exhaust gases in the turbine housing, the lubricant turns into carbon. Sooner or later the rings cease to seal.

Imho the overall design of the turbo bearing housing needs to be revised.

[bvolcko38]

What about a ceramic seal?

[Kai]

Take the complete turbo- put one hand on the end of the compressor wheel shaft and the other on the end turbine wheel shaft. Notice how easy it is to wobble the complete shaft up and down.

The design is supposed to be like this: due to its very high rpm the shaft runs in floating bearings- there is oil pressure both on their inside against the shaft and outside against the bearing housing. You need a seal that allows for this fairly high clearance and the high temps in the turbine housing: so far a design incorporating minuscule piston rings as presently installed has shown most promise.

An alternative could perhaps be to use non coking aviation turbine oil- such as Aerocharger did when they had their competition snow scooter turbos un the market. It would of course require redesign of the complete oil system.