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Friday, August 28, 2009

RB26DETT Cam Timing Adjustment



SLIDING ADJUSTER
Adjustable Cam Gears Assembled Checking the pistons and camshafts position with dial gauges Measuring crank angle with a scale board

The simple graph makes it easy to change the engines characteristics with the simple sliding adjustments of the Cam Gear. If the intake valve timing is advanced (i.e. 120° to 110°) then performance gains are achieved at low RPM. If the intake valve timing is retarded (i.e. 110° to 120°) then performance gains are achieved at high RPM. Camshafts with no dowel pin attached will require you to check the timing adjustments with a dial gauge and scale board.

EASY VALVE TIMING ADJUSTMENTS WITH PONCAM
The Poncams valve timing has been preset at 110°. This Valve Timing has been calculated as the best setting for both performance and drivability. You can adjust the engines performance by making adjustments with the cam Gear carefully. This easy adjustable system is a great advantage over other conventional designs.
 
The engines output character can be changed just by re-adjusting the close timing over the intake valve as shown below.

- Turn Cam Gear to anti-clockwise (advanced timing): torque at low RPM
- Turn Cam Gear to clockwise (delayed timing): torque at high RPM

The standard Valve Timing is set to “0” on the scale. When you adjust the scale to +/- 3 on the scale (3 degrees) that will be +/- 6 degrees on the crank angle. The maximum range is +/- 10 degrees on the Cam Gear which is +/- 20 degrees on the crank angle. Please don’t move the adjustable Cam Gear from zero position until the engine adjustment has been completed. If the cam Gear has been fitted without being setup on the initial key position then the engine wills not opperate normally. If the valve timing has moved too much from the setting due to engine vibrations then the operation of the engine will get worse or in worse case scenario the pistons may hit the valves.


Cam Timing adjustments.
Intake side
Advancing timing - turning the pulley counter clockwise - you gain power at low RPM.
Retarding timing - turning the pulley clockwise - you gain power at high RPM
Most adjustable cam gears can be moved +/- 10 degrees which is 20 degrees of cam timing on most aftermarket cam gears.


Camshaft lobe centers in 106 and ex 108 is best starting place
264 or 272 up to 600ps (Advancing the intake cam a little +4 degrees really helps low end response)
* Type A
Designed to best suit the stock & N1 turbos for optimum performance balance of low to mid range torque.
The Exhaust cams duration was reduced to maintain best idling.
* Type B
By extending the duration timing compared to the Type A Poncams, both response and peak power was raised and these camshafts best compliment the mid to large size turbo charged applications. 


PONCAM SPECS
Max Cam lift (° )Max Cam lift
(mm)
Valve Timing
Centerline
(Deg)
Cold Valve Clearance
(mm)[±0.01]
TYPE
IN
DURATION
EX
DURATION
LIFT(IN)
LIFT(EX)
IN
EX
IN
EX
A
260°
252°
9.15
9.15
110
115
0.45
0.38
B
260°
260°
9.15
9.15
110
115
0.45
0.38

RECOMMENDED SETUP 

TYPE A
TYPE B
CATALYTIC
CONVERTER
Sports Catalytic Converter
or Straight Pipe
Sports Catalytic Converter
or Straight Pipe
TURBO
Stock or
Larger Bolt On Type
N1 or
Full Turbo Kit Upgrade


Type
Application
Duration(IN)
Duration(EX)
Lift(IN)
Lift(EX)
Part number
MSRP(USD)
R
BNR32,BCNR33
250°
250°
9.15
9.15
143051
$580.00
BNR34
143052
* TYPE R(for Stock Cat. Equiped Cars))
The Type R camshafts were designed due to popular demand from end users who are looking at upgrading the performance potential of their GTR while staying within the limits of recent street legal requirements. Recent laws on emissions and exhaust noise was made stricter in Japan so to have a quieter car by running smaller exhaust systems raises the exhaust back pressure which greatly reduces the response and hinder performance. Our engineers then designed these Type R camshafts to suit the needs of those who need to keep such setup and benefit with performance gains.


KEY DESIGN CONCEPTS
*To improve performance gains on cars running catalytic converters
*To maximise the stock turbos performance potential.
*To reduce the exhaust back pressure
Improves overall throttle response and torque
To protect the stock turbos performance limits and minimise turbo failure.
Back Pressure
(for Stock Cat. Equiped Cars)
Engine RPMExhaust Pressure
7,200 rpm1.9k
* J-ING Test car setup during acceleration
(in 4th gear from 2,000rpm to 8,000rpm)
Peak Power Comparison
(for Stock Cat. Equiped Cars)
TYPE A405 ps
TYPE B406.33 ps
TYPE R404.65 ps
The peak power output is less than the Type A & Type B camshafts but the response is better with the Type R camshafts.
  
PONCAM TYPE R SPECS


TYPE
IN
DURATION
EX
DURATION
IN LIFT
EX LIFT
IN
VALVE
EX
VALVE
IN
V- CLEARANCE
EX
V- CLEARANCE
R
250°
250°
9.15mm
9.15mm
110°
110°
0.45mm
0.38mm

HKS V-Cam
Variable valve timing on the intake cam. 3 different setups. Seems to be popular on GT-R's in Japan now.

Buy HKS V-Cam here

STEP1

Features
  • The intake cam side of the RB26DETT is changed to allow variable valve timing. The cam has duration of 248° which seem a little conservative. However, with the variable timing, power increases can be found at low or high RPM
  • Whether you are looking to find some time on the circuit through improve acceleration out of lower speed corners, or simply want something which can overtake with ease on the street, the HKS V Cam System provides good power from low RPM reducing the necessity for excessive gear changes. This especially noticeable when going from vacuum to boost to give the feeling of increased displacement.
  • Improved valve timing will allow for more complete combustion leading to improved fuel efficiency and cleaner exhaust emissions.
  • HKS V CAM System is compatible with the stock pistons. (When using with the thinner head gaskets or modified cylinder head, the clearance between valve and piston may be insufficient.)
  • Exhaust Cam should be selected dependent on turbo choice.
    (Recommended: GT-SS-256°, GT2530-264°)
Test vehicle specification
  • Engine: RB26DETT(EX-side 256°)
  • Turbine: GT2530 x 2
  • Intake: Super Power Flow, Airflow-less
  • Exhaust: HKS Metal CAT, Legal Muffler
  • Cooling: Intercooler & Piping Upgraded
  • Fuel: Upgraded Pump (280R/h), I/J 600cc
  • Engine Management: F-CON V Pro (D-jetro), EVC

STEP2

Features
  • Specially designed cam for Step 2 has duration of 264°, valve lift 8.7mm. Acceleration at high rpm is smoother than solid Step 1 camshaft (272IN-272EX). Step 2 is suited to higher power output at all range of engine rpm.
  • Strength is enhanced when used with upgraded Valve Springs at high RPM (recommended limit 8500rpm).
  • Engine output and torque are substantially improved at all engine RPM range compared to solid Step 1 (272IN/EX). Step 2 was designed to show significant power and torque improvement for vehicles tuned to output 600ps or higher compared to old type Step 1 type B (256EX).
Test vehicle specification
  • HKS 2.8LKIT STEP1 φ87
  • HKS Racing Suction Reloaded Intake Kit
  • HKS Head Gasket 1.2mm
  • HKS Fuel Delivery Kit
  • HKS GT2530KAI x 2
  • HKS 1000cc Injectors
  • HKS Head Bolts
  • HKS Spark Plug M45
  • HKS F-CON V Pro
* Boost Pressure - 150kPa
* This result on the graph above is obtained by in-house engine bench test. The result may vary depending on measuring instruments

STEP PRO

Features
  • V CAM system for higher levels of tuning compared to Step 1 and Step 2.
  • Specially designed cam has duration of 264°, valve lift 10mm. Reviewing cam material, profile and valve timing change, Step Pro is suited to higher power outputs at high rpm.
  • Billet camshaft is used to enhance strength even when used with upgraded Valve Springs at high RPM (recommended limit 8800rpm). Added strength facilitates a hollow cam design has allowing Step Pro to be 560g lighter than Step 1 and Step 2.
  • Valve timing has 50° adjustment from 80°~130°
  • Exhaust cam can be selected to suit vehicle specifications.
  • Step 2 Valve Springs are required.
  • Recess modification of the cylinder head is required.
Test vehicle specification
  • HKS RB26DETT 2.8L KIT STEP2
  • Exhaust Camshaft: HKS Camshaft STEP2 272°
    Valve lift-10.2mm
  • Turbine: TO4Z (Boost-1.2kg/cm2)
  • CAT: HKS Metal Catalyzer

Complete Parts
STEP1STEP2STEP PRO
Special Intake "V CAM"248°264°264°
(Billet Construction)
Variable Valve Timing Unit(High torque compatible Vane Type, Ni plated pulley)Variable amount 30°Variable amount 50°Variable amount 50°
Special Intake Cam CoverUnpaintedUnpaintedUnpainted
Control Unit *F-CON V Pro Ver.4F-CON V Pro Ver.4F-CON V Pro Ver.4
OCV (Electromagnetic type)
Oil Filler CapHKSHKSHKS
Cam Angle Sensor (High accuracy type)
Oil Line (From Engine to Cam Cover)
Other short parts
* F-CON V Pro Ver.4
  • Need to set with your own car For F-CON V Pro Ver.4 setting.
  • Need to purchase F-CON harness.
Other Necessary Parts
STEP1STEP2STEP PRO
EX CamshaftSelect according to turbo size
HKS Forged Piston KitRecommendedRequiredRequired
HKS Oil Pump Upgrade *RecommendedRecommendedRecommended
* Stock f77 and N1 f81 are available but may not provide ample pressure at low rpm to adjust valve timing. For this reason, HKS Oil Pump is recommended.
Notes for Usage
[RPM Limits]
STEP1      : 8,000rpm (Stock rev limiter)
STEP2      : 8,000rpm (Stock Valve Spring)
               : 8,500rpm (Upgraded Valve Spring is required/Available separately)
STEP PRO: 8,800rpm (Upgraded Valve Spring is required/Available separately)
[Oil/Water Temperature]
When Oil is at lower temperature, higher viscosity may prevent valve timing from reaching the desired figure.
Cam will not advance if water temperature is below 20℃
[Engine Oil]
Recommended: SUPER OIL (RB), Racing Pro Oil 10W-50.
[Timing Belt]
Please check for the tension and wear in every 10,000km and adjust/replace if necessary.


Parts for RB26 Timing Belt Change

Timing belt -13028-20P25
Tensioner- 13070-42L00
Idler- 13074-58S00
Tensioner Spring- 13072-58S10

Water Pump - 21010-21U26
N1 Water Pump - 21010-24U27


2 comments:

Anonymous said...

That is not correct.

Retard the exhaust cam will give you more low down response. Advancing the inlet cam will give you better top end.

best know setup for a std Rb26dett is -4 ex and +2 inlet. This equates to -2lines and plus 1line on the cam wheel as each mark is 2 degrees at the crank.

Sean Morris said...

You have it backwards. Not sure which RB26's you are playing with, but not the ones I am.

-4 on the intake side is actually advancing the cam.

What does the HKS V-Cam do? Why do they only use it on the intake side? Check the operation of it, then get back to me.

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