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Home , Inlet manifold

R32 & R33 Skyline Specific

Under Construction – Last Updated 18th June 2004

This Guide was made possible from the following forum discussion hence people R33 RB30 Conversion on Skylines Australia

Head Selection Head Plenum

Block Rods Bearings Oil Pump Oil Squirters Water Pump

ECU AFM Injectors Turbo Gearbox/Clutch

Factory Specs Cam Setup 1 Cam Belt Setup 2

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk! Heads:

Three heads can be used for the twin cam conversion. • RB26DETT Head • RB25DE (R32) Head • RB25DE/T (R33) VCT Head

The RB twin cam heads have around 62 cc to 64 cc combustion chambers. The RB30 SOHC heads have around 56cc to 58cc combustion chambers.

The RB26DETT head from the R32/33 GTR bolts straight up with the only modifications requiring you to drill the RB30E’s head bolt holes to suit the RB26DETT heads larger head bolts. All water/oil galleys line up.

The R32 RB25DE head bolts straight up to the RB30E bottom end. All water/oil galleys line up.

The R33 RB25DE/T has variable cam timing (VCT), it also has slightly different designed inlet ports that require the RB25DET inlet manifold to be used. The inlet ports look slightly larger due to the different design around where the injectors reside. However both the R32 RB25 & R33 RB25 ports are the same size. The R33 RB25DE/T head has a slightly different design around the front inlet cam side of the head as seen below.

RB25DET VCT Bottom End RB30E Bottom End No-VCT oil galley

As you can see from the above pictures, the RB25DET VCT bottom end has the provision for the VCT’s oil supply where as the RB30E bottom end does not. If using the R33 RB25DE/T you must modify the head to suit the RB30 bottom end then decide how you are going to supply oil to the VCT. Some have ran a T-piece from the oil pressure sender, then drill & tapped in to the heads VCT oil galley.

The RB20DE/T has smaller ports and valves compared to the RB25DE/T heads. The RB20DE/T Inlet valves have a diameter of 30mm, and the exhaust valves have a diameter of 27mm. The R32 & R33 RB25DE/T Inlet valves have a diameter of 35mm, and the exhaust valves have a diameter of 29.5mm.

If you have an R33 use the top end from the R33 RB25DE/T. If you have an R32 use the top end from the R32 RB25DE. This will save a LOT of problems related to sensor and fuelling compatibility.

There seems to be a little bit of a rumour floating around that the RB25DE NA valve springs are too soft. It is a rumour, ignore it. Providing the head hasn’t done hundreds of thousands of kays the valve springs are perfectly fine for the standard installed. If you look at changing cams then possibly look in to heavy duty valve springs if they are warranted.

Some where over the 9-9.5mm lift the R32 RB25DE & R33 RB25DE/T heads will require some machining to allow for the greater lift.

There has been a few reports of problems running over 1bar of boost with the NA valve springs (Valve bounce/flutter). Some have problems some do not. Darren and I both bought our heads from the same place at the same time and had both of the heads rebuilt, ported polished at the same time also. Darrens head for some reason didn’t have high enough seat pressure which required shimming where as mine was perfectly fine. Comparing the two heads together Darrens head had the valves & valve seats sunken further in to the head where where as mine were sticking up ever so slightly. This ~.3mm difference could possibly be why the valve springs weren’t applying enough seat pressure. So get your head checked out, don’t just slap it on. Or to be on the safe side get your set a set of GTR valve springs.

Head gasket:

This comes down to personal preference. O-ringing the block and using a genuine RB30E is one of the best ways to go. I used a COMETIC metal head gasket that has a built in O-ring setup. Similar to some of the Jap brands.

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk! Plenum & Inlet Manifold:

Obviously the R33 & R32 RB25 inlet manifolds have a different design around where the injectors reside as stated in the heads section. Use the bolt on bits from the head you are using. If you start trying to mix and match you will run in to problems. Best to keep things simple. There is no advantage from using the R33 over the R32 head or vice versa.

For comparisons sake here is a pic of an RB20DET Inlet manifold with a R32 RB25DE gasket over the top. Note the port size difference. The R33 RB25 & all GTR ports are slightly larger than the R32 RB25’s.

Exhaust Manifold:

RB25/20/26 blocks compared to the RB30 block has a different designed water galley that runs from the water pump to the rear of the block on the exhaust side of the . The RB30 galley is almost flush up against the deck where as the RB25/20/26 blocks have the water galley sitting well beneath the deck. You will be required to remove the protruding metal from the water galley in order for the gasket & manifold to be bolted up. You will only require a few millimetres to be removed. See attached picture.

Block:

The VL Commodore Series II block has provision for the turbo’s oil & water. If you get your self a series one block you will have to drill and tap the holes that have been blanked off. It is not a problem as drill and taping to suit your connections is not difficult.

The RB30’s head restrictor oil feed holes are approximately 1.8mm in diameter, where as the RB25/20 twin cam blocks are 2.4mm. The top end still will receive enough oil. Leave it as is the smaller restrictors will prevent your catch can from filling up as often when the motor is pushed hard.

Ensure you use the RB20/25/26’s oil dip stick & holder as the RB30 one is not long enough to clear the twin cam’s plenum/inlet manifold.

You will have to use the RB20/RB25 hose attachments accordingly. They are situated on the inlet side of the motor at the front where the resides and towards the back of the motor roughly where cylinders 5 & 6 reside.

Sump:

Due to the longer rod length the RB20/25/26 will have to have the fins grinded off the inside of the sump. As far as I am aware the RB30 sump has no clearances issues in the R32/R33 Skylines.

Pistons:

RB30ET Pistons ~7.1:1 CR. This is way to low you will loose response and fuel economy. RB30E Pistons ~8.2:1 CR which is better however 8.5:1-9:1 is preferred.

The RB25/26 spec pistons have a smaller deck height. Hence the will sit lower in the when at TDC.

The squish band (quench) is an important factor when building a performance motor and should not be over looked. The quench clearance should be around the .76mm – 1.52mm (0.030” – 0.060”). A nice safe quench clearance for a high 6500+rpm engine is 1mm – 1.37mm (0.040-0.055”) The quench is the measurement of deck clearance plus the head gasket thickness.

High rpm motors (6500+rpm) tend to bend/stretch a little at high rpm. Hence crank bends, rods stretch, and pistons rock. If you don’t know what squish is Google it, make sure you do and know what you are talking about as most engine builders over look this important design late model use. Squish affects performance & economy. It also allows you to run more , boost and static CR before detonation occurs. It has the same affect as running a higher octane fuel.

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk! Rods:

Prepped stock rods will hold up to around 350rwkw reliably. A set of forged H-beam rods are likely to cost in the vicinity of $1500-1800.

Crank:

The crank is nitrated from factory, providing it is in good condition linishing is only required. On some high km RB30 cranks the front and rear seals eat away at the crank a little, if bad enough this has to be re- sleaved.

Bearings:

The Genuine Bearings are good. Clevites & King Performance bearings are both excellent. Ensure you have plenty of oil flow (pressure is not so important), tolerances are correct and you will have a tough motor on your hands.

Oil Pump:

Many have had success using the RB30ET oil pump. It is best to use an oil pump from a twin cam motor, turbo or non turbo to suit your requirement. The R32 RB20/25/26 oil pumps all bolt up to the RB30E crank with no issues. Some R33 RB25DE/T oil pumps will bolt up others will have the newer larger crank engagement lugs, depending on the year of the Series I R33 obviously, generally Nissan made the move over to the larger lugs some where during 1995.

The reason for Nissan upgrading the lugs to larger design is that there has been reports of oil pump failures generally when up around 9000rpm+ hence a missed gear. This is not a problem with the RB30 as it will never be reaching 9000rpm due to harmonic issues at approximately 7500rpm. The simple fact is the RB30 does not need to rev over 7000rpm to make big power (700hp).

If you are looking at high rev’s and more power (different cradle & stiffen up bottom end to stop harmonics) you are better off using a R33 GTR oil pump and using a JUN adaptor ring.

Ensure you use lock tight on the bolts when assembling the oil pump as they are known to rattle loose and loose oil pressure.

Oil Squirters:

The only RB motor that does not use the piston oil squirters is the RB30E/T. The oil squirters are designed to squirt oil towards the bottom of the piston, this helps remove heat from the piston in turn improving reliability.

Ceramic coating the tops of the pistons works better than oil squirters. It contains the temperature within the . You get cooler running and more horsepower. When you use oil squirters some of the combustion temperature is passed into the oil obviously which is not good also the oil flowing upwards underneath the piston slows the motion of the piston down, and thus absorbs horsepower.

Adapting the oil squirters to the RB30 block is possible however the oil gallery is apparently in a slightly different position to those in an RB20/25/26. So machining is required to make them fit.

Water pump & Thermostat:

All of the water pumps are interchangeable. The RB30E water pump is the cheapest setting you back from $70 to $90. For more water flow the RB26 N1 water pump can be used. Use an aftermarket RB30E thermostat or a Genuine RB20/25DET thermostat. The genuine items look a lot better quality. You will be also required to use the RB20/25 thermostat housing so the original lower Skyline radiator hose will attach to the same place.

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk! :

All of the RB20/25 are interchangeable. Use a clutch to suite what you have.

Twin plates are always good just expensive.

ECU:

The R32 ECU’s can be re-mapped, AP Engineering PowerFC’s are also available.

If you have an R33, I would be using a PowerFC.

Ensure the ECU you select supports the following features: • Closed Loop • Knock Sensor • Sequential Injection • 6 ignition drivers

No Closed Loop mode, your will drink the fuel. No Knock Sensor, one bad batch of fuel could cause detonation and the loss of a piston or head gasket. No sequential Injection, reduced fuel consumption and less power. No 6 ignition drivers, waste spark & possible overheat and damage to your coils due to them being fired in batch mode.

The R33 & R32 ECU’s will handle the RB30DET with no problems. It is probably best to run the motor in on the stock ECU with stock injectors & turbo.

AFM:

The standard RB20/RB25DET AFM’s are 80mm. They will handle up to around 220rwkw before running out of scope. Two options are to use the Z32 AFM (80mm) or a Q45 AFM (90mm). The Z32 AFM runs out of scope around 260rwkw where as the Q45 will handle up to around 300rwkw.

It is possible to get more power out of your AFM as many factors affect the efficiency of your engine. I.e cams, headwork etc.

Injectors:

The R32 RB25DE uses top feed injectors that are the same size as the R32 RB20DET injectors (270cc’s), with a little more fuel pressure these will make up to 220-240kw at the rear wheels.

The R33 RB25DE/T use side feed injectors. Turbo injectors are 370cc’s.

Turbo:

For around and just over 300rwkw the HKS3037 & Garret GT35 600hp turbo’s are the best bet for response and reliability.

If you select a .61 to .69 exhaust a/r the turbo will kick really hard with control being almost impossible. The .81 to .87 exhaust a/r will increase full boost lag by around 500rpm, the turbo comes on a little smoother allowing throttle control to be just that little bit easier, it will also allow for better top end performance.

Gearbox/Clutch:

All of the gearbox’s bolt up to each other with each clutch also bolting up as the spline of the gearbox(s) input shaft is the same. They are all interchangeable.

Series 1 R33’s & R32’s have a push type clutch setup, Series 2 R33’s use a pull type setup which is much stronger than the push setup which is prone to breaking. There’s isn’t too much involved to change the push to a pull setup.

The RB20T gearboxes will hold up to around 250rwkw no problems providing you run street tyres. The moment you slap on a set of slicks or nitto style tyres it will let go.

The RB25T gearbox is known to hold up to 450-500rwkw.

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk! Factory Cam Specs:

Cam Cam NVCS Engine Cam lift Cam lift Lobe centre Lobe centre Model Type Duration Duration range code IN(mm) EX(mm) angle (IN) angle (EX) (IN) (EX) (rpm) BNR32 125° BCNR33 113° BCNR33 RB26 Solid 240° 236° 8.58 8.28 120° N1 DETT BNR34 BNR34 117° 121° N1 R31 RB20DET Lash 248° 240° 7.80 7.80 108° 118° RB20DE 232° 7.30 111° 117° 240° 7.80 HCR32 RB20DET Lash 115° 120° 240° 7.80 RB25DE 232° 7.30 111° 118° 1050 RB25DE 5700 ECR33 Lash 240° 240° 7.80 7.80 120° 117° 1050 RB25DET 4500 below RB25DE 6.90 5700 ER34 Solid 236° 232° 8.40 119° 115° below RB25DET 8.70 5400

This information was pulled from Tomei's web site.

When mix and matching cams you are able to use exhaust cams as an inlet cam however due to the CAS requirement you are unable to use inlet cam as an exhaust cam. So no R31 248 duration in the exhaust side /

With regards to the NVCS, experimentation has indicated that the more boost and power you make best results are achieved by allowing the NVCS to engage at a lower RPM. The only way to find out is by experimentation or through the use of a computer simulated engine dyno package such as Dyno2003. It is pretty obvious that as you make more power the same airflow is achieved at a lower rpm hence the requirement of NVCS engaging at a lower rpm. This is also reflected when comparing the rpm of NVCS engagement for the turbo and non-turbo engines.

GTR solid cams do fit the hydraulic R32 RB20 & RB25 heads, I am unsure with the R33 RB25DET. The hydraulic followers are supplied with oil from a galley within the head via a hole to the follower, weld up the oil supply holes to the hydraulic followers. Then block off one of the oil supply holes from the block to the head.

From factory the GTR’s block has one of oil supply holes blocked, there are 2 oil supply holes, one near no.2 which is the one that is blocked off and one near no 5 cylinder at the back of the block.

Generally when overhauling a GTR engine further oil restriction is used by using a smaller rear restrictor (hence Tomei RB26 oil restrictors). Under high rev’s the oil even with one restrictor blocked off tends to be dumped to the top of the motor not leaving enough in the sump which under hard cornering causes oil surge.

Bottom end rpm limit is more of an issue than the hydraulic follower rpm limits, especially with the RB30 bottom end. Piston speed reaches approx 4100 by 7500rpm on a RB30 compared to the GTR’s piston speed of 4100 at 8500rpm. The only real benefit is that you will be able to play with second hand ‘cheaper’ GTR cams.

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk! Cam Belt: There are two different methods to get the cam belt fitted. I’ve came across a couple of different people (VL Turbo Owners) who have done this conversion. I’ve borrowed their pictures for now until I get my own. :D Thanx peoples you know who you are.

1. This method uses the standard Idler bearing and but re-locates the tensioner bearing above the water pump. The following pictures are using the RB25DE Non-VCT Head.

Due to the extra deck height of the RB30 Block you will require a belt that is approximately 11 teeth longer. A total of around 152 teeth will be needed the Dayco part number for this setup is 94407.

When using the above left setup Andrew from City Dismantlers found the tension was greater than the factory recommended spec of 20kg’s, even though the tensioner had been completely slackened off as much as it could without fouling the timing cover. He has since used another tensioner in place of the idler bearing near the crank (above right) in order to bring the belt tension down to the factory recommended spec of 20kg’s. Use the RB20/25 lower cam belt cover as the RB30 cam belt cover is slightly taller which fouls with the top tensioner.

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk! 2. This is the second method of adapting the cam belt.

It uses a Gates POWERGRIP GT2 p/n 1200 8MGT 30 It measures 1200mm long, 8mm pitch on teeth, 150 teeth, and 25mm wide but it was cut down from 30mm in the factory. The following pictures are of the R33 RB25DE/T VCT Head, note the tensioner setup & different inlet cam gear.

As you can see the idler bearing is replaced with a tensioner bearing.

The Nissan RB style tensioners can be used safely on the (tight) side of timing belt as it is a locking type. Set the load upon the belt at 20kg’s and lock it.

There is also a Bosch belt that can be used VB-T866.

This document is a guide all of the information contained within could possibly be incorrect. Use it at your own risk!