Three main journal bearing types, their selection

Polytetrafluoroethylene (PTFE), commonly known as Teflon, is a thermoplastic polymer material whose high chemical inertness, self-lubricating property, and low friction coefficient makes it a suitable material for rolling-element bearing cages, journal, and sliding bearings, among others.

Metal-polymer plain bearings consist of a metal backing, usually steel or bronze, onto which is sintered a porous bronze layer that is then impregnated with PTFE and additives to obtain a running surface that offers anti-friction and wear resistant bearing properties.

• Pressure Dam Bearing. Pressure Dam bearings are essentially a plain journal bearing with a pocket cut in one half that has an abrupt stop at some point in the shell.
• Offset Halves Bearing.
• Tilting Pad Journal Bearing. Tiling pad journal bearings are comprised of multiple pads that are supported by pivots.

Garrett Ball Bearing turbochargers spool up 15% faster than traditional journal bearings. Tests run on CART turbos have shown that ball-bearings have up to half of the power consumption of traditional bearings. The result is faster time to boost which translates into better drivability and acceleration.

Ball bearing turbos offer unmatched throttle response, spooling up to 15% faster than traditional journal bearings. Ball bearings have less friction for the compressor and turbine to spin on. Thus they are faster to spool. This improved responsiveness equals better acceleration.

6 to 8 pounds per square inch

All journal bearings have shaft play!

(Radial play) It does not allow the blades to hit the case on the compressor side but it almost does. The allowable tolerance is between 0.010″ and 0.020″ measured radially at the nose nut.

Full ball bearing turbos DO NOT need oil, thats the whole point, they use cermaic bearings instead of oil. Because they elimintate the oil, they also eliminate the parisitic drag that goes with it, oil cook, and are more durable.

Journal Bearing Turbo An oil restrictor is generally not needed except for oil-pressure-induced leakage. The recommended oil feed for journal bearing turbochargers is -4AN or hose/tubing with an ID of approximately 0.25”.

Oil pressure entering a ball-bearing turbocharger needs to be between 40 psi and 45 psi at the maximum engine operating speed. For many common passenger vehicle engines, this generally translates into a restrictor with a minimum of 0.040″ diameter orifice upstream of the oil inlet on the turbocharger center section.

A turbo restrictor is essentially a tube fitted directly on the turbocharger’s air intake. We will not go into very technical (bureaucratic) details on their geometry but their main purpose is to reduce the turbine’s air intake flow and, consequently, its output.

Turbo systems are made up of moving parts which spin at incredibly high speeds, and work under intense heat and pressure. This means that they need a constant flow of quality engine oil to lubricate the compression valve and intake and outlet fans, to reduce wear and help them perform at their best.

Just as you need to warm up your engine, you need to let it cool down. Extended journeys and high speed driving creates a lot of heat in your turbocharger, and if you turn off the engine whilst it’s still hot, you can cook the oil inside, leading to unnecessary build up of carbonised oil inside your turbo.

A turbo is more efficient than a supercharger since your engine does not need to work harder to power the turbo. Because a turbo is not connected directly to the engine, it can spin much faster than a supercharger.

Consumer Reports, for example, concluded that downsized, turbocharged engines typically achieve worse mileage than larger engines without turbochargers. In their tests, Ecoboost Ford Fusions using turbocharged, four-cylinder engines burned more fuel than their larger, naturally-aspirated counterparts.

The major upside of a turbo inline-four is that is achieves similar power levels as a V6 while using less fuel, costing less, taking up less space, and weighing less. A turbo works by taking exhaust gases and forcing them back into the cylinders.

Engines with high compression ratios or turbochargers often require high octane fuel found in premium gas for optimal performance and fuel efficiency. However, the majority of cars on the road today are optimized to run on regular gas.

150,000 revolutions per minute

As well as increasing power, turbos increase torque – an engine’s strength – particularly at low revs. That’s useful in small petrol engines which tend to produce not much torque at high revs without a turbo. Turbocharged cars also have quieter exhaust pipes.