mass-hole wrote:
Nothing yet. The flanges are different on every turbo I have ever seen but some are close. Good candidates would be the gtb2056vk and gtb2260vk but neither are ball bearing. Gtb2060 and 2260vklr are factory ball bearing turbos and liquid cooled but have extremely weird exhaust housings.
Over at the TDI forums there is some debate on whether ball bearing is really worth it on small diesels. While they help spool because of the low drag at low speed, some folks argue that journal bearings are better at high speeds. Since our turbos are small and generally live at higher speeds >100,000 rpm since diesels run a lot of boost at all times, it's possible for the journal bearings to be better for most people who just cruise around without too much off and on of the gas pedal. If you spend a lot of time in traffic than a ball bearing may be better.
On the big cummins/dmax/psd trucks, they have massive turbos(the 6.0 PSD had a GT3782, 82mm compressor wheel vs our 56mm) by comparison and they spin a lot slower even at full bore so they likely see the benefit of ball bearings at any speed. Their peak rpm's are probably where our turbo runs all day long.
I don't really know the answer but I do know that because I am at 6500' my stock turbo is pretty laggy off the line so I would like to get a ball bearing setup despite what I wrote above.
One thing to note is that Garrett uses steel ball bearings. Any good aftermarket turbo, and mine, use ceramic balls that outperform steel balls in every aspect except price. They also use whats known as a "rigid" pre-load system where everything is held in place tightly, nothing moves. As rpms climb the balls and inner races get flung outward and run in their "sweet spot". At some point though as the rpms get even higher the races and balls really start to push into the outer race. Since nothing can move they have no choice but to cause lots of friction, which is why those turbos resist high rpms vs journal bearing turbos. Ceramic balls help in that they deform less than the softer steel balls, decreasing rolling resistance.
Im going to use a spring pre-load system that will allow the bearings to move and adjust to the rpms. As the rpms climb the outer race can shift to allow the balls and inner race to continue running in their "sweet spot". This isnt new technology, its been used for decades in the aerospace industry, i guess its just new to turbos. its also listed in the bearing manufacturers bearing book as *THE* way to achieve the highest rpm capability of the bearing.
As of the debate of if its worth it on a diesel? My opinion is it must be if all the new diesels are starting to get them. Once you put a ball bearing turbo on you wont want to go back.
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