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Journal Bearing Turbo vs. Ball Bearing Turbo
When choosing a turbocharger, the very first thing to decide on is whether you’d like to use a journal bearing turbocharger or ball bearing turbocharger. These are two common types of bearing systems used in turbochargers, each offering unique performance characteristics. We’ll be discussing the key differences between these two systems below.
Design and Operation
Looking at a turbocharger from its appearance we’re unable to tell whether it’s a ball bearing or journal bearing turbo. The bearing system lies inside the cartridge; when you open up the cartridge you’ll see the design of ball bearing and journal bearing system completely different from each other.
- Journal Bearing Turbocharger
Journal bearing uses a thin film of oil to create a fluid barrier between the shaft and the bearing surface; the shafts float on this oil film during turbo operation, where the shafts rotate within the sleeve of the bearing.
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Ball Bearing Turbocharger
Ball bearing system uses balls to support the shaft, as the balls roll instead of slide like journal bearing shafts, they create less friction and allow for faster and more efficient rotation. Ball bearing designs require less oil consumption than journal bearing designs.
Spool Time/Turbo Response
< Vehicle: 2000 Subaru Impreza /Turbo:KURO Series /Source:IG @reliablesubiegarage / Tuner: @snailperformanceaz>
The spool time/turbo response refers to how quickly each system allos the turbo to reach its optimal operating speed.
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Journal Bearing Turbocharger
Journal bearing type turbocharger generally has a longer spool time, meaning it spools slower than the ball bearing types due to more friction and drag. The oil film also takes a bit more time to build up and support the shafts, affecting responsiveness.
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Ball Bearing Turbocharger
Due to its structure and design ball bearing type turbocharger spools faster as it has less friction, leading to quicker response and faster boost.
Efficiency
< Vehicle: Subaru WRX /Turbo:KURO GTX3076R /Source:IG @eastcoast_rex>
Efficiency of a turbocharger is quite important especially when you use it for events like drag race, as you need the turbo to act up soon.
- Journal Bearing Turbocharger
- Ball Bearing Turbocharger
Ball bearing turbos are more efficient due to reduced friction. The rolling motion of the ball bearings reduces energy losses, making them more efficient oferall, especially at higher speeds.
Durability and Longevity
Durability and longevity is certainly important factors to consider especially when you’re using the turbo for daily drive.
- Journal Bearing Turbocharger
Journal bearing type turbos are more sensitive to oil quality and pressure. Poor lubrication can lead to quicker wear and failure, but with proper maintenance, journal bearings can be very durable.
- Ball Bearing Turbocharger
As the load is distributed across multiple points (the balls), ball bearings are generally considered as more durable, as they also handle thrust loads better, extending turbocharger lifespan.
Cost
< Vehicle: Nissan s13 1991 /Turbo:LAB Z ST60 (G25-550) /Source:IG @kfracingexhaust
When considering their cost differences, make sure you consider also the other factors mentioned above, as everyone use the turbo for different needs.
- Journal Bearing Turbocharger
Journal bearing turbochargers have been in the market longer than the ball bearing types, they are typically less expensive because of simpler design and lower manufacturing costs.
- Ball Bearing Turbocharger
Because the structure and design of ball bearing turbochargers are more complex and precise, they are more expensive to manufacture therefore they cost more. However, under proper usage the cost is often justified by improved performance and longevity.
Heat Management
<Vehicle: Mitsubishi Evo / Turbo:KURO GTX28R/ Source:IG @cino_jr @elaborazionitaglienti>
High temperature cause the turbo components to wear faster, therefore having good heat management also impacts the longevity of a turbocharger.
- Journal Bearing Turbocharger
Journal bearing turbos relies heavily on oil both for cooling and lubrication, but when oil overheats, it can lead to bearing failure.
- Ball Bearing Turbocharger
The ball bearing design is better at handling high temperature due to its lower friction. However, same as journal bearing turbos, proper cooling and lubrication is critical for turbo longevity, and they are generally more tolerant to extreme conditions.
Maintenance and Rebuilds
<Vehicle: Subaru WRX / Turbo:TD06SL2 20G/ Source:IG @baxleysspeedshop>
As mentioned above multiple times, maintenance is important for turbo lifespan, this also means the cost incurred can be also considered when evaluating between these two bearing types turbo.
- Journal Bearing Turbocharger
Since the journal bearing design is simpler than ball bearing, it is easier and cheaper to rebuild.
- Ball Bearing Turbocharger
Design of ball bearing turbos involve more complexity and therefore are harder and more expensive to rebuild.
Application
<Vehicle: BMW E92 / Source:IG @hmudaart >
Various purpose of the vehicle impacts the selection of bearing type, car manufacturers and garage also consider different factors for the cars they build.
- Journal Bearing Turbocharger
Journal bearings are common in OEM (Original Equipment Manufacturer) applications where cost and simplicity are prioritized over performance.
- Ball Bearing Turbocharger
Ball bearing turbos on the other hand are often used in high-performance or racing purposes where quicker spool-up and better efficiency are critical. These turbochargers are more popular in aftermarket upgrades when owners need them for particular events or when they seek for more power and better performance than factory.
Overall ball bearing turbochargers are more expensive to install and maintain but in return they offer better performance especially in terms of response and efficiency. However, journal bearing turbochargers are more affordable both in its cost and maintenance, but some performance characteristics are being trade off.
