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incredible newbie question...external difference for BB turbo?


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yes but aren't there non-BB turbos out there that also have both oil and water lines?

Yes. The short answer is there is no way. You have to be 'edumucated' about the specific turbo to know for sure. If you are looking at a very specific turbo, you can try comparing to lots of stock photos from vendors. That's about the best I can tell ya. You will know if you can get your hands on it to compare.

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A ball bearing turbo cannot be rebuilt but by a few places. The nameplate should be intact; it's usually riveted to one of the housings. You cannot disassemble the center section to visually see the bearings, but you can do this:

Lay the turbo on the table so the shaft is horizontal to the ground.

Reach into the compressor wheel and spin it as fast as you can.

Watch how long it takes for it to stop moving.

 

A BB turbo can take 10~30 seconds to stop moving. A journal bearing will take perhaps up to 10 seconds.

 

That's a rough estimate, but you'll get a feel for it. BB will want to free spin quite a lot. I've seen BB turbos you could lay flat and blow on them and they would spin. Journal bearing won't do that.

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A ball bearing turbo cannot be rebuilt but by a few places. The nameplate should be intact; it's usually riveted to one of the housings. You cannot disassemble the center section to visually see the bearings, but you can do this:

Lay the turbo on the table so the shaft is horizontal to the ground.

Reach into the compressor wheel and spin it as fast as you can.

Watch how long it takes for it to stop moving.

 

A BB turbo can take 10~30 seconds to stop moving. A journal bearing will take perhaps up to 10 seconds.

 

That's a rough estimate, but you'll get a feel for it. BB will want to free spin quite a lot. I've seen BB turbos you could lay flat and blow on them and they would spin. Journal bearing won't do that.

 

I would like to point out, that my holset is a journal turbo but only ever had full synthetic oil, I could blow on the impeller and get it to spin. It would also spin close to the 30second mark with a good hand twist. My holset is still on the original engine (6bt cummins, ~163,000km).

 

If the turbo is rebuilt and dry inside, spinning it by hand may not be good for it.

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I would like to point out, that my holset is a journal turbo but only ever had full synthetic oil, I could blow on the impeller and get it to spin. It would also spin close to the 30second mark with a good hand twist. My holset is still on the original engine (6bt cummins, ~163,000km).

 

If the turbo is rebuilt and dry inside, spinning it by hand may not be good for it.

Fair enough point on the spin rate. I'm sure the OP need to just feel two of them; you can pretty much tell after that point. OTOH, I doubt you'll damage a dry turbo by spinning it by hand when it's built to achieve several hundred thousand revolutions per minute.

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