I ran some test on the Turbos I have.

Test setup,

I plugged the waste gate port and used a air compressor spray nozzle to spray 160 PSI @ 50CFM air into the exhaust port of the Turbo.

Result,

The Turbo that had a lot of end play would ramp up nicely but at a certain point would kind of begin to oscillate much as a tire out of balance would. This oscillation would get bad enough to actually slow the Turbo down.
You could here the change in speed as the vibrations began.

The other Turbo I had that had hardly no end play in the shaft did not do this and would coast to a stop 30 seconds after the air was stopped.

Keep in mind these were not under any real load, nor was the oil pressure to the bearings up to speed. I sprayed some light weight oil in the oil ports before I ran them. Also they were cold. Figure things might change a lot once the metal expands.

 

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Because we live in the year 2011, Turbo, metallurgy, computers, blade design and manufacturing have improved ALOT over even the past decade, let alone a turbo that was designed in the early 80's using 70's technology.



Nissan did this to make the turbo last longer. A car driving over a long period of time on the freeway will heat up that turbo alot, even if you aren't on the gas much. Plus of course there is the added benefit of having a faster cool down.



They didn't have water cooling, because the engines they used where air cooled! The life of an oil cooled journal bearing turbo is proven to be shorter then that of a water/oil cooled turbo used in the same manner. You can go to any road course and ask around. There is also a damn good reason why just about every turbo car made from 1985+ is water cooled.[/QUOTE]

NO....Radial endplay is not as detrimental as axial endplay. Radial endplay is required for journal bearings to function with oil.Seriously, as long as there is NO axial endplay, if the compressor wheel is not touching the housing, Radial enplay is acceptable. I've ran MANY turbochargers with a "decent" amount of endplay at over 40psi for many thousands of miles. The life of an oil-cooled journal bearing turbo is NOT proven to be shorter than that of a water-cooled turbo. The REAL reason that OEM turbos started to come water-cooled was the due to the ignorance of the general public and the proper cool-down of turbochagers. OEM manufactures added watercooling to increase the life of turbos FOR GENERAL PUBLIC who would hotrod a turbo car around and shut it down without letting the oil cool. In an oil-cooled turbo, this would cook the oil inside the turbo, damaging bearings and seals. To prevent this, water-cooled turbos dissipate heat through the water lines. OEM holset hx35's have seen 1million+miles at over 20psi.....and are oil-cooled.

Oh, and ebay turbochargers are hit and miss. a few of my buddies are running 30+psi on ebay turbochargers without any issues, barking them every day. One of my friends made 550+whp in his rb26 with an ebay turbo. Gotta take care of your turbos

 

I agree. But some play is acceptable.Actually, I believe they peak out around 90k.You think consumer metal (steal, aluminum, etc) has really progressed that much in the last 30 years? Or, more realistically, do you think they'll be using these newer, more expensive metals to rebuild a 1980 turbo with 2010 methods and designs? Let's be realistic here. No. They won't.Oil is still a coolant and lubricant. Yes.Just like the turbo.I'd rather have an independent lab confirm this vs some shade tree mechanic and weekend racer.Because people are idiots and don't care for their equipment properly. I said that already.