Difference Between Ball Bearing And Bush Bearing

[aquariuz6]

can anyone tell me the difference between ball bearing and bush bearings in turbos?

quicker spooling? longer turbo life? etc.

[Abo Bob]

Ball bearing is more expensive, spools much earlier in the rev range (lower boost threshold), longer life.

Bush bearing is cheaper, higher boost threshold, shorter life.

[aquariuz6]

what do you mean by lower boost and higher boost threshold?

how many kms do ball bearings tend to last? what about journal bearings?

[R31Nismoid]

www.howstuffworks.com

great site

[Slide]

With first hand experience with journal bearings and ball bearings i can say that journal are now not as sad as what people think.

And with newer technology comes faster spool times

Properly assembled and maintained they can have an infinite life.

Links to a little more help here

http://www.skylinesaustralia.com/forums/in...40#entry2137926

[Sydneykid]

As usual it’s not what they tell you that’s important, it’s what they don’t tell you. Journal bearings require consistent oil pressure. In a turbo (spinning at 100,000 rpm with an 800 degree exhaust off one end) any decrease in the oil pressure/flow will lead to instantaneous failure. This is not the case with ball bearing turbos, they can tolerate periods of zero oil pressure. Any small contamination in the oil has a similar result, as does overheating the oil.

Many plain bearing turbos are not water cooled, so the oil has to perform both the lubrication and the cooling tasks. This transfers excessive heat into the oil system.

Nissan didn’t spend $Millions with Garret developing ball bearing water cooled turbos for no reason. Personally, I see no sanity in downgrading from the standard, ball bearing, water cooled turbo to a plain bearing one.

cheers

[scathing]

Nissan didn’t spend $Millions with Garret developing ball bearing water cooled turbos for no reason. Personally, I see no sanity in downgrading from the standard, ball bearing, water cooled turbo to a plain bearing one.

Hey, there are plenty of other sanity-challenged people that love referring to the fact that old Nissans didn't have BOV's as a reason why you don't really need one.

[SkylineSII]

http://www.skylinesaustralia.com/forums/in...ic=115981&st=40