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Nov 25, 2007

RB26DETT information : The myths , the truths


The RB26DETT. An engine of much myth. We are going to try and set out some truths. Remember to trust nothing you read on the internet, or is it trust everything that you read on the internet?

1000 horsepower stock bottom end?

  • It is possible for some finite amount of time. When it lets go, it will probably be #6 ring land

Just put a chip to make 500 horsepower on an RB26dett?

  • The stock MAF will run out of range. The stock injector will run out of range. The ceramic turbos, if it has them, will be on the edge of life. 

Is it true that the RB26 early block from the BNR32 is very durable compared to other standard blocks?

Is the RB26dett, 330 horsepower stock?
  • At 8 psi the engines make horsepower in the 276 horsepower, 280ps range.  With more boost, they make more power.  Open them up at all, they make more power. 
  • Rated at 280 ps (Pferdestärke) or 276 horsepower stock from 1989-2002
    • Found in the R32, R33, R34 GT-R
    • Also found in the Stagea 260RS (aka Nissan Skyline GT-R Wagon)
    • The RB26DE was available in the Autech R32
  • Inline 6 cylinder
  • Iron block
  • Aluminum head
    • 24 valve
  • 2568cc of displacement
  • 86mm bore x 73.7mm stroke
  • Twin turbo
  • Individual throttle bodies - that is six in groups of 2
  • Coil on plug ignition
  • Interference engine
  • Stock R32 Dyno chart
R34 RB26dett - Nissan Skyline GT-R

Top of the motor
  • Valve/Cam covers
    • Aluminum. Black on R32/R33. Red on R34. Nur  or #EY0 - Silica Brass (Nur Engine Cover) Nurs. Two breathers located at the back of the plenum. Drivers side goes to PCV
      valve. There is a crossover tube. Left side goes to the inlet side of the rear turbo. 
  • Spark plug cover
    • We like to leave them off to keep the coils cooler. The engine looks
      more finished with the spark plug cover. You know the piece. Says
      Nissan Twin Cam 24 valve on it.
RB256LS1 in disguise

  • PFR6A-11 are the stock plugs
    • Heat range 6
    • 1.1 mm gap
  • NGK are the best plugs
    • BCPR7EIX are one heat range cooler and iridium
    • We like the racing NGK when we are serious. Double fine wire heat range 10

  • Camshafts
    • Intake 8.58 240 duration 113 deg Lobe Center -R34N1 117 deg Lobe Center
    • Exhaust 8.28 236 duration 125 deg Lobe Center-R33N1 120 deg Lobe Center - R34N1 121 deg
    • Camshaft valve clearance check and adjustment
    • Camshaft seal - 13042-16V00 (Same as 240SX)
  • Valves
    • Intake 34.5 mm
    • Exhaust 30 mm(sodium filled)
  • Head bolts
    • (14) 12 mm head bolts
  • Head
    • 4 valves per cylinder
    •  Twin cam
    •  Cam on bucket
    •  Shim under bucket adjustment
  • Head gasket
  • Timing Belt
  • Woodruff key
  • Damper
    • R32 is unique due to PS pulley offset
    • R33/R34
  • Timing Gear

RB26 combustion chamber

Induction side
    • Lean cylinder is #6.
  • Throttle body
    • 6 individual throttle bodies. Cars have done over 1000 whp on stock throttle bodies.
    • Do not clean unless you reseal them with throttle coat
  • Balance tube
    • Vacuum/boost and water pass though the balance tube

Exhaust side
  • Exhaust manifold
    • Stock
    • Nismo
    • N1
    • Stock manifold on left, Modified N1 on the right

  • Turbocharger
    • Ceramic exhaust wheels that break off
      • The RB26 used a ceramic exhaust wheel to reduce the weight and interia, plus increase the heat capacity of the turbocharger. Great in theory, but in real life, overspinning the turbo, or detonation causes the ceramic wheel to become detached from the turboshaft.  Anything above about 14 psi, about 1 bar is considered dangerous. However even with less boost, and bouncing off a rev limiter (like a Bee-R limiter) will most likely result in missing exhaust wheels, and normally aspirated, low compression RB26's.  
  • Downpipe(Frontpipe)
    • Stock is relatively small diameter 
    • Has a flex tube in it. The flex tube is important due to the rocking motion of the engine
    • If going aftermarket, the only way to go is equal length. The sound is so much nicer
    • R32 and R33
      • Inlet to Front pipe      55 mm = 2.17 inches
      • Outlet of Front pipe  65 mm = 2.55 inches
OEM exhaust gasket this is looking at inlet to frontpipe/downpipe. 

Bottom end of the engine

  • Pistons
    • 86mm. Stock pistons are oil cooled.
      •  1.5 mm top ring, 1.5 mm 2nd ring. 
    • N1 has 1.2 mm top and 2nd ring
  • Rods
    • 121.5mm center to center. 
    • RB28's have 119.5 c-c except in a GT block(RRR)
  • Oil squirters
  • Crankshaft
  • Main cap/girdle
    • Seven main bearings. 
      • #4 being the center main bearing and containing the thrust bearing. 
    • The other six main bearings are all the same construction.
    • Bottom end of the RB26 showing the main girdle
  • Oil pump
    • The early cars- pre 1991 had a narrow oil pump drive as listed above
    • The only way to remove the oil pump, is to pull/drop the pan, as the oil pump relief valve prevents you from pulling it straight off the end of the crank
    • The OEM design leaves some areas to address, as it has a tendency to be loose on the crank drive. The looseness eventually causes the oil pump to crack at the flats. This causes oil to push out the front main seal
    • We had tons of problems with N1 oil pumps, and won't use them on any of our builds
    • There are some aftermarket solutions, such as spline drives.

  • Oil pan
    • Cast aluminum
    • Contains the front differential
    • Weighs about 55 lbs
The front differential is on the right side of this picture
24U block. This is an N1 block
    • 05U on the side. A standard block.
    • 24U on the side. An N1 block
    • RRR on the side .GT Block . That one is special
    • RB30
    • RD28
Engine Control Unit
  • MAF
    • 65mm. Each will meter air up to about 200 whp each.
  • Fuel injectors
    • 444 cc. 
    • Yellow top.
    • Top feed
    • Low impedance
  • Fuel pump
    • 195 liters per hour - R32
  • Crank angle sensor
  • R34 CAS on the left, R32/R33 on the right
    • R32-R33
      • Late R32 and early R33 had a slightly different looking sensor
      • R34
    • The R34 uses a different cam drive for the sensor.
    • R34 CAS

    • Checking ignition timing and TDC


  • Inlet piping
Divided twin turbo pipe

    • Rear inlet piping collapses under boost. Replacing it with hard pipe is recommended. KTS makes a hard pipe suction kit for the TT.  I recommend it if you are staying twins and want a factory looking setup. 
  • Intercooler
    • Stock intercooler will provide better response to approximately 600 wheel horsepower.
    • The factory cooler is front mount, fairly large for a stock part, with large (80 mm od) inlets and outlets. 
    • 24 inches x 10 3/4 inches x 2 1/2 inches
    • Weighs approximately 18.9 lbs (Dynosty)

Buy RB26 , RB26DETT parts here. Gasket kits , water pumps , timing belts , camshafts. New OEM, and aftermarket parts. .


Anonymous said...

Is it true that the RB26 early block from the BNR32 is very durable compared to other standard blocks?

Oh this is bugging me in a while as well- what is the OEM head gasket thickness of the RB26? I've been seeing different posts on forums, some say 0.9 while others up o 1.2 just like aftermarket ones.

Sean Morris said...

Everyone says the early blocks are better. Not sure if there is any truth, or just urband legend.

The stock headgasket is 1.2 mm.

Anonymous said...

Hi Sean! Do you consider the RB26's PCV valve a "maintenance part" lets say every 100k kms or so? Coz I've heard some mechanic says so to avoid horror stories of oil leaks. If so when do we GT-R guys replace them?

And does it literally just screws in w/o any need of teflon seal tape? I also read some blunders on stripping the threads of manifolds because of replacing this part.

Sean Morris said...

Everything in a car is a maintenance part. I am sure the PCV valve has a schedule, but like most, its replace when it has an issue. I would use sealant on it when I put it in. As far as damaging it, well its dissimilar metals, so you have to be a bit careful. The valve is stronger than the manifold piece. At worst you can always helicoil.

Urmom said...

An early block is good because its prestressed. When BMW used the M10 (2002 motor) as their first turbo 1.5L powerplant for F1, they used old weathered blocks