Nissan Skyline R33 GTST - OEM Turbo Unit

OEM Turbo Unit

Location: Exhaust side of engine

New video below

As you look at the turbo (fitted to vehicle) you will see the "Exhaust Side" on the right, and is usually a rusty shade of colour, this is due to the heat produced under heavy acceleration.
If you have gone as far as removing the heat sheild, you will also see the "Boost Actuator".
Typically these are fixed type - a bar going from the Pressure control solenoid to the exhaust side of the turbo.

The standard turbo on the RB25DET has Nylon Blades on the Intake Turbine Wheel, and Ceramic Blades on the Exhaust Turbine Wheel, held together by a floating shaft.

These were used in order to keep the weight down from the moving parts

The Nylon / Ceramic wheel combination also allows for quicker spool up

The turbo is water cooled, via pipes coming from the engine block, into the turbo and back into the engine again.

Its also oil cooled at the same time as its lubricated by the oil, and the PCV (Positive Crank Ventilation) hose that crosses intake and exhaust banks on the engine, and then into the turbo - although i have to look properly on my RB25 to confirm this.

Due to the light and fragile blades on the OEM turbo, the max safe boost pressure is
0.85Bar or 12.49Psi

Can a larger turbo be fitted?

Yes. However further high capability parts are needed before this stage is reached, and it also depends on the power output your setting for.
Usually larger injectors are needed, high flow fuel pump, AFM is replaced, or removed alltogether during an ECU Upgrade or Remap of the existing unit. These should be dealth with either before a new larger turbo is fitted, or during installation.

The same can be said for turbos of the same size but with steel internals, and set to run higher boost levels - and chances are all the other parts started to fail / malfunction before boost pressure was adjusted.

If you are looking to run above 1 Bar (14.7 - 15Psi) then the head gasket should be replaced for a thicker one, to lower the compression in the engine. If this is not done then you may run into problems, like Blown Head Gasket (B.H.G), detonation, lean or rich running. In a worse case scenario it could damage conrods, crankshaft, pistons and the head itself.