Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   Insert BS here (https://www.miataturbo.net/insert-bs-here-4/)
-   -   Journal Bearing vs Ball Bearing (https://www.miataturbo.net/insert-bs-here-4/journal-bearing-vs-ball-bearing-18913/)

Saml01 03-28-2008 10:13 AM
Journal Bearing vs Ball Bearing
 
I am a bit confused. So journal bearing turbos have only one bearing in a grove while ball bearing turbos have packed bearings surrounding a shaft?

Why don't turbos just use the same type of bearings that engines use? Which aren't really bearings at all, the crank and rods are separated by a film of oil.

Braineack 03-28-2008 10:26 AM
Originally Posted by Saml01 (Post 234835)
Why don't turbos just use the same type of bearings that engines use? Which aren't really bearings at all, the crank and rods are separated by a film of oil.
that's what a journal bearing is...its a brass sleeve with holes in it...


BB turbos spin for about 37 minutes after you shut the car off, journal bearings...maybe .5sec.

http://www.turbobygarrett.com/turbob...h101_speed.jpg

patsmx5 03-28-2008 10:27 AM
Originally Posted by Saml01 (Post 234835)
I am a bit confused. So journal bearing turbos have only one bearing in a grove while ball bearing turbos have packed bearings surrounding a shaft?

Why don't turbos just use the same type of bearings that engines use? Which aren't really bearings at all, the crank and rods are separated by a film of oil.
I hate quoting Wikipedia but it will be fine for this discussion, as I don't think bearings is a highly debatable subject.

A bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle.
Our engine uses journal bearings/fluid bearings.

Saml01 03-28-2008 10:33 AM
Originally Posted by Braineack (Post 234841)
that's what a journal bearing is...its a brass sleeve with holes in it...


BB turbos spin for about 37 minutes after you shut the car off, journal bearings...maybe .5sec.

http://www.turbobygarrett.com/turbob...h101_speed.jpg
OHHHHHH.

Well that clears everything up.

Thanks Pat, Fluid Bearings explains everything as well.

I was confused this whole time.

This also explains why oil pressure is so important to journal bearing turbos.

You guys are great.

Markp 03-28-2008 08:58 PM
Originally Posted by Braineack (Post 234841)
that's what a journal bearing is...its a brass sleeve with holes in it...


BB turbos spin for about 37 minutes after you shut the car off, journal bearings...maybe .5sec.

http://www.turbobygarrett.com/turbob...h101_speed.jpg
This graph shows how BB turbos are superior, but not that superior! Once under boost, the bearing matters naught. Thanks, I'll take the cheap ass rebuildable at home sleeve bearing unit. After 2 seconds, it's all about the $1,000 I saved.

Mark

y8s 03-28-2008 10:01 PM
Originally Posted by Markp (Post 235125)
This graph shows how BB turbos are superior, but not that superior! Once under boost, the bearing matters naught. Thanks, I'll take the cheap ass rebuildable at home sleeve bearing unit. After 2 seconds, it's all about the $1,000 I saved.

Mark
point two?


All times are GMT -4. The time now is 12:52 PM.


© 2024 MH Sub I, LLC dba Internet Brands