Turbo bearing ques

[Roy]

Was thinking about the plain bearing turbo that i currently run, or shoudl i say sits in thr boot of my car:(

Spinning the compressor / turbine you get a feel for the difference between it and some the HKS turbos i have seen, namely 2835/3040 & T51.

But i got to thinking the fact that its not installed and running on the car, hence has no oil pressure around the bearing... is spinning the turbine whilst the thing is in your hand indicative of the sort of friction/resistance in this sort of bearing setup?

Or once they have pressurised oil in their core do they spin easier. I guess im thinking they would spin easier, but i aint really sure...anyoen stripped a plain bearing turbo and have a good idea of the lubricated faces / oil films in the core?

[ylwgtr2]

Once it gets oilpressure the bearing floats in the housing and the shaft floats in the brearing...so once its gets pressure...yes its easier...imagine spinning a tennis ball in water

[Roy]

I imagined as much, im curious to know the difference. On paper you would imagine it spins easier...is it about 20% better or perhaps 50% better?

[dwhe009]

its about 10,000 times easier with oil pressure. As ylwgtr2 says, when there is oil pressure there is no contact between the bronze bearing and the housing, and no contact between the shaft and the bearing.

I have one in my fingers right now.

Pull it apart very carefully for yourself, thats the best way to learn about things.

Make sure you have clean hands and clean everything with petrol, then add oil when you put it back together.

[Roy]

Yeh ive seen the inside of an old CA18 turbo with only a 270deg bearing etc. But its pretty hard to suss out just how easily the shaft spins with oil pressure as opposed to when sitting in your hand.

Anyway, i guess my answer the difference is dramatic, so thanks

[ylwgtr2]

and mark the position of the comp wheel when you take it off...altho you should balance it anyway

[tang0]

when i was installing the gcg high flow tubby, i span the wheels, and they didnt really feel that free rolling, however, now its in the car, i can hear the turbo spin down for about 5-8 seconds when you turn off the engine ... the plain bearing did not do this ! i can only put it down to the free rolling now the turbo has oil in it !