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Rb25/30 Rb30det Vvt Internal Oil Control

psi

By psi,
in Engines & Forced Induction

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  • 3 months later...
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fletch rb30
fletch rb30

33 and 34 vct activation is different. On 33 heads, the oil constantly feeds the front journal to lubricate it. The oil leaves the journal via the vct solenoid into the head. When the vct engages the

daisu
daisu

Just to get an idea of how it works, is this what is happening with the oil feed?

psi
psi

I've heard of a few plugs that refuse to play the game. I thought I would have that issue and got some brass just incase.. If you do break or mangle it, you will have to make a copy. Nice pics

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  • 1 month later...
  • 1 month later...
Dorifta Collaborator

Dorifta

Posted
Posted
I han't done a Neo head.. but I'm guessing that Nissan didn't stray too far from what they already know works.

Please take another pic, up close and front on, just like mine so everybody can see what your looking at.

Top work on the mod. Im about to embark on this procees, Where did u get the replacement plug, Did u press it back on or hammer

Thanks

fletch rb30 Enthusiast

fletch rb30

Posted
Posted

I have had a look at the neo head and it has a bearing feed running off the head gallery and a seperate feed just for the vvt.

You wont be able to pull the plug out and drill it like the r33 head.

Im appears the vvt solenoid blocks the oil pressure when the vvt is off and when engaged, it pressurises the vvt solenoid. when disengaged the oil pressure bleeds back through the solenoid instead of the constant loss

  • 1 month later...
boost is good Enthusiast

boost is good

Posted
Posted
I have had a look at the neo head and it has a bearing feed running off the head gallery and a seperate feed just for the vvt.

You wont be able to pull the plug out and drill it like the r33 head.

Im appears the vvt solenoid blocks the oil pressure when the vvt is off and when engaged, it pressurises the vvt solenoid. when disengaged the oil pressure bleeds back through the solenoid instead of the constant loss

just doing the conversion atm.. looking at drilling through the bucket gallery into the vct gallery between the first cam journal and first lifter bore then plugging the entry point back up.. anyone know what the original neo oil restrictor size is for the vct.. I only have a head thanks

  • 2 weeks later...
  • 1 month later...
jarrod83 Community Regular

jarrod83

Posted
Posted

Tried this mod whilst doing my rb30 conversion, worked great, was very simple and tidy

drilled out the oil returns in the head and ran a rear head oil drain kit but decided not to restrict or block the oil feeds in the block, but i seem to be losing a hell of a lot of oil still from the breathers. . . i was wondering if anyone has considered drilling out the 1.5mm oil in the brass plug to 2mm, in theory i would think the head would still have enough pressure to engage the vct but also drain more oil when the vct is off in the higher revv range

has anyone tried this? or think it may work?

Cheers

Jarrod

  • 4 weeks later...
JonnoHR31 Grand Master

JonnoHR31

Posted
Posted

going to be doing this shortly for my 30det. theres plenty of info around on restrictor sizes with or without vct, but all the info for vct heads include an external oil feed. what size restrictors would work best with this internal feed on a street driven 30det? i ordered a couple off the net and got sent 1x 1.5mm and 1 blocked, worried it might not be enough oil for normal driving?

dkshauno Apprentice

dkshauno

Posted
Posted

I'm building a 25/30 combo but don't want to use the VCT, is it better to have the solenoid off or on?

I'll be doing this mod but only to supply the front cam tunnel with oil.

Has anyone got any info on not using the VCT?

cheers shaun.

JonnoHR31 Grand Master

JonnoHR31

Posted
Posted
good point. Whatever was there - I'd assume the RB30 restrictors then.

Wonder what size they are?

2mm i think. factory 25 are 1.5mm i think.

i ended going with 2 ~1.6mm feeds, works out a little less than factory 25 by my calculations which should stop any blow by without starving the head

jarrod83 Community Regular

jarrod83

Posted
Posted

Johnno let us know how your engine goes, i think the rb30s have two 1.8mm standard, with leaving them standard i was still getting way too much oil to the head.. a bit of spirited driving would result in quite alot of oil coming out of the breathers... i think im going to 2x1.3mm this time

Jarrod

jarrod83 Community Regular

jarrod83

Posted
Posted

Forgot to mention, thats with a rear head oil drain and all of oil drains drilled out in the head only, and the two factory rear oil drains dremeled out a bit, as well as the smaller restrictors im going to try and stick a descent sized hose from my catch can to the sump to allow both oil to return and the blowby from the engine to escape without clogging up the oil returns in the head

Jarrod

JonnoHR31 Grand Master

JonnoHR31

Posted
Posted (edited)

does anyone have any pics of exactly where to drill out the oil drains in the head?

now you have me wondering if i should make them smaller than 1.5mm, are the standard 25 feed definately 3x1.5mm? because i wasnt getting much blowby at all with the 25 so i figure aslong as i keep it less than standard 25 it should be fine

Edited by JonnoHR31
jarrod83 Community Regular

jarrod83

Posted
Posted

With regards to the oil restrictors in the rb25 standard, im not 100% sure to tell you the truth, i have heard conflicting sizes, most people say the two feeds are 1.5mm, but when comparing them to the size of my 1.5mm tomei restrictor they look slightly smaller, i have heard of ppl measuring them up to be 1.3mm, the vct feed i have heard it being anywhere from 1.5-1.9mm =/, when my engine is apart ill measure whats in there now

As for the oil returns, you can see at the bottom of the block what holes go through to drain into the sump, so just follow them through to the head and youll know what to drill.. from memory im pretty sure all the small oil return holes are on the exhaust side, im going to attempt to get the two large holes at the back of the head drilled out more, i know a drifter that claims he drills them out a fair bit.. i only dremeled them up abit as i was afraid of hitting anything important.. ill let you know what gets done, but it wont be until i get my engine pulled back apart next holidays

Jarrod

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