Turbo Question
There are a number of other factors in the bb units. They come standard with water cooled centers, that with the bearings and you do not have to let them cool so long before shutdown, They can also last longer at extreme high boost levels due to a different thrust design. I figured, I am spent an arm and a leg anyway, what is an extra $600!
TECH Apprentice
Joined: Jul 2004
Posts: 374
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Conventional, floating sleeve bearings last in HD diesel applications for 1/2million to a million miles, I’m not sure that you really need more durability then that. If you kill conventional bearings in less then the life of a few engines you’re doing something wrong, most likely involving ingesting stuff through the wheels, damaging them, imbalance/dirt/deposit issues or oiling issues.
Second, it’s much more difficult to design a ball bearing that will survive long term at high speeds and it’s unlikely that any ball bearing will outlast any floating or semi floating sleeve design. That’s just a fact of life. A ball bearing requires metal to metal or ceramic to metal contact, a floating or semi floating sleave has no metal to metal or any other hard surface contact UNLESS you do something like starve it for oil.
There are a few turbos out there that have undersized shafts (notably the larger GT turbos) where ball bearings may help in longevity, but not in bearing life but in keeping the shaft straight after repeated heavy loading and unloading (I’d imagine, though I have no numbers to this effect, that high boost in something like a road race or ralley situation would be worse then most of our street and strip antics), but that is not a real advantage with the BB design, but an issue with a deficiency of the turbo’s design.
That pretty much leaves the only real advantage being faster spool, which is true and an issue when you’re talking about something like a 1.6L Honda spooling a T76, but properly sized, most V8 turbo applications shouldn’t need any real help spooling, unless we’re talking about something like an extreme bleeding edge application like twin T88’s on a small block setup to make 2K hp…
Second, it’s much more difficult to design a ball bearing that will survive long term at high speeds and it’s unlikely that any ball bearing will outlast any floating or semi floating sleeve design. That’s just a fact of life. A ball bearing requires metal to metal or ceramic to metal contact, a floating or semi floating sleave has no metal to metal or any other hard surface contact UNLESS you do something like starve it for oil.
There are a few turbos out there that have undersized shafts (notably the larger GT turbos) where ball bearings may help in longevity, but not in bearing life but in keeping the shaft straight after repeated heavy loading and unloading (I’d imagine, though I have no numbers to this effect, that high boost in something like a road race or ralley situation would be worse then most of our street and strip antics), but that is not a real advantage with the BB design, but an issue with a deficiency of the turbo’s design.
That pretty much leaves the only real advantage being faster spool, which is true and an issue when you’re talking about something like a 1.6L Honda spooling a T76, but properly sized, most V8 turbo applications shouldn’t need any real help spooling, unless we’re talking about something like an extreme bleeding edge application like twin T88’s on a small block setup to make 2K hp…
