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Sunday

Nissan RB20DET - Engine Tuning

 



The RB20 engine is one of the larger Nissan RB family of engines that were produced between 1985 and 2002.

The RB20 family included 7 engine models:

  • RB20E
  • RB20ET
  • RB20DE
  • RB20DET
  • RB20P
  • RB20DET-R
  • RB20DE NEO


Read the History of the RB Engine on the Link Below.

Wikipedia


Nissan RB20DET Engine Specifications

The RB20DET was a turbocharged version of the RB20DE. This new version made use of a Garrett T28 turbocharger, running a boost pressure of 7 psi.

Below you’ll find the key specifications for the Nissan RB20DET:

  • Production Years: 1985-1993 (Yokohama Plant)
  • Cylinder Block Alloy: Cast-iron
  • Configuration: Straight-6
  • Valvetrain: DOHC 4 valves
  • Piston Stroke: 69.7mm (2.74″)
  • Cylinder Bore: 78mm (3.07″)
  • Compression Ratio: 8.5
  • Displacement: 2.0L (1998cc)
  • Stock Power: 215 bhp
  • Stock Torque: 196lb-ft
  • Weight: 245kg (540lb)
  • Turbocharger: Ceramic wheel Garrett T28 w/ T3 flange
  • Tuning HP Potential (Max HP): 400+
  • Nissan RB20DET – Everything You Need To Know


RB20 Camshaft Upgrades.




Significant gains on the RB20 can be made from camshaft upgrades. 
Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output. 

Fast road camshafts usually boost the torque throughout the rpm band, you might lose a little low end torque but high end rpm power will improve. Motorsport camshafts, boost the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers. For a road car we recommend that you look at where you spend most time in your RPM range and then match your bhp range to your usage of the car. I would be surprised if you find a RB20 Motorsport cam is a pleasure to live with when driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

What is lift?

Lift, in camshaft terms, is how far the camshaft lifts the valve. On the RB20DET engine, both the intake and exhaust camshafts have 7.8mm of lift. The popular Tomei Poncam upgrade (which are direct drop-in camshafts, compatible with the stock valvetrain), features 8.5mm of lift on both the intake and exhaust camshafts.

What is Duration?

Duration, in camshaft terms, is how long the valve is held open by the lobe on the camshaft. In the case of the RB20DET engine, the intake camshaft has 240° (degree’s) of duration, and 240° of duration on the exhaust camshaft. One of the more popular, bolt on camshaft upgrades, the Tomei Poncam’s, increase duration to 256° of duration on both the intake and exhaust. The increased duration means the valve’s remain open for a longer period of time, allowing more air/fuel to enter the cylinder.

Increasing both the lift and duration of an engine’s camshafts allows more air/fuel to enter the cylinders, which in turn, means more power can be produced. When increasing the lift and duration of camshafts, one must ensure the valvetrain is capable of handling the increased lift and duration. Many stock valve trains can handle slight increases in lift. The lift of the RB20DET camshaft can be safely increased from 7.8 to 8.5mm with stock valve springs. Beyond this, stronger valve springs designed for higher lift are required.


Tomei Adjustable Cam Gear (Nissan RB20/RB25/RB26)

Note: Several poster’s on SkylinesAustralia.com have argued that certain camshaft upgrades don’t require adjustable cam gears, as the manufacturers of the camshafts did enough R&D to maximize the camshafts potential without requiring adjustable gears.

RB20 Camshaft Upgrades




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Thursday

Cycloidal Transmission Rebuild.

 A number of rolling presses that we maintain are equipped with a Japanese gearbox or transmission that is extremely compact and powerful.

The cycloidal discs in the transmission roll around the ring gear and rotate at a much slower speed than the input shaft, providing high torque, low backlash, and a high degree of rigidity. 

Here is some History

Cycloid technology traces back to the German engineer and designer Lorenz Braren [de]. In the 1920s, he developed an innovative gearbox that eventually became known as the Cyclo. He received a patent for this cycloid gearbox invention in 1925. Subsequently, in 1931, he founded his company, Cyclo GmbH, in Munich and began serial production of cycloid gearboxes in the 1930s. Thanks to a licensing agreement in 1937 with a Japanese company, now part of the Sumitomo Heavy Industries group, the first Cyclo drives were also produced under license in Japan starting in 1939.



One such transmission had a very noisy failure, and we were able to strip and rebuild it without much difficulty.


After separating the electric motor from the Cycloid, our first challenge became evident.


Due to the high load and great amount of torque needed to drive the rolling mill, the keyway between the 22KW electric motor and the cycloidal transmission was chewed up.


This is what the key should look like on the left


Replacing the damaged unit with a spare. We rebuild these transmission so that there is always a spare for "just in time maintenance" like this.


The shaft and keyway on the electric motor were also damaged, and that would require refurbishment.


After splitting the cycloidal transmission we found the cause of all the noise.
The main shaft bearings had collapsed.


The deep groove ball bearing had disintegrated, allowing the balls to roam freely in the transmission. Very noisy, and by some miracle, did not seize or damage the other moving parts.


Remnants of the bearing cage can be see all over the transfer rollers and the cage.


We started with the electric motor by removing the armature and rebuilding the shaft. Machining the shaft to size and milling a keyway came next.  Here we have completed and induction and resistance test on the windings. All OK!


The stator fitted with new bearings and ready for installation. Shaft machined to size and keyway milled.


Here we begin with the cycloidal cage, greasing and assembling al the pins and rollers.
New gaskets are cut and holes punched.


The main output shaft machined with a new internal keyway.
New bearings fitted throughout the transmission.



A quick reminder of all the parts we are working with.


The eccentrical bearing pair pressed into place and the deep grove main shaft bearing now ready to be mated to the cycloidal cage.


Cycloidal cage ready for installation.


Cycloidal discs and pin rollers all in place,


Finally the drive end is ready to be mated to the cycloid cage, and walla, that -that...


Some hours later, the cycloidal transmission is assembled and ready to be mated to the electric motor.


Refurbished drive output shaft.


Refurbished stator shaft.


Here we go, the cycloid and the electric motor and being mated together.


Painted and ready for delivery.


A quick video of the transmission and electric motor on the test bench.
Voltage and current test complete😊 





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