Oil Restriction

[ahh 33 s2]

hey all i have just been researching oil restiction for this build. i have taken the following info from the major thread. info was provided by gary (sydney kid) and can be found on page 153. here it is again. hope this helps some ppl

RB26 cylinder head= 2 oil feed galleries between the block and the head

We block one off, same as RB26's are standard

We use a 1.5 mm restrictor in the other

Plenty of oil flow to the camshaft bearings, not too much oil slopping around in the head, getting chucked into the catch can and leaving the sump in short supply.

RB25 with VVT= 2 oil feed galleries between the block and the head

Plus 1 feed to the VVT actuator

We block one off, same as RB26's are standard

We use a 1.5 mm restrictor in the other

Plus leave the VVT oil feed as per standard

Plenty of oil flow to the camshaft bearings and VVT actuator but not too much oil slopping around in the head, getting chucked into the catch can and leaving the sump in short supply.

RB25 without VVT= 2 oil feed galleries between the block and the head

Plus 1 feed to the VVT actuator

We block one off, same as RB26's are standard

We use a 2.0 mm restrictor in the other

Plus block off the VVT oil feed

and a couple of diagrams

http://www.skylinesaustralia.com/forums/in...st&id=26521

http://www.skylinesaustralia.com/forums/in...st&id=26522

the only question i still have that i have not been able to find an answer to is,

does it matter which gallery you restrict and which you block off??

dan

[Sydneykid]

hey all i have just been researching oil restiction for this build. i have taken the following info from the major thread. info was provided by gary (sydney kid) and can be found on page 153. here it is again. hope this helps some ppl

RB26 cylinder head= 2 oil feed galleries between the block and the head

We block one off, same as RB26's are standard

We use a 1.5 mm restrictor in the other

Plenty of oil flow to the camshaft bearings, not too much oil slopping around in the head, getting chucked into the catch can and leaving the sump in short supply.

RB25 with VVT= 2 oil feed galleries between the block and the head

Plus 1 feed to the VVT actuator

We block one off, same as RB26's are standard

We use a 1.5 mm restrictor in the other

Plus leave the VVT oil feed as per standard

Plenty of oil flow to the camshaft bearings and VVT actuator but not too much oil slopping around in the head, getting chucked into the catch can and leaving the sump in short supply.

RB25 without VVT= 2 oil feed galleries between the block and the head

Plus 1 feed to the VVT actuator

We block one off, same as RB26's are standard

We use a 2.0 mm restrictor in the other

Plus block off the VVT oil feed

and a couple of diagrams

http://www.skylinesaustralia.com/forums/in...st&id=26521

http://www.skylinesaustralia.com/forums/in...st&id=26522

the only question i still have that i have not been able to find an answer to is,

does it matter which gallery you restrict and which you block off??

dan

I thought I was quite specific when I posted "same as RB26's are standard" ie; the front one

Cheers

Gary

[ahh 33 s2]

sorry but am not to familiar with the rb26 nor any engine atm moment. so sorry to ask pretty much the same question again, so you restrict the front gallery?? yes?

[Cubes]

RB25 without VVT= 2 oil feed galleries between the block and the head

Plus 1 feed to the VVT actuator

We block one off, same as RB26's are standard

We use a 2.0 mm restrictor in the other

Plus block off the VVT oil feed

I ran with a single 1.5mm up front and blocked rear as suggested in the thread.

The setup seems ok and has travelled quite a few kms but from day one I was getting a little valve train noise for a fraction of a second following start up of which was not there prior.

If I were to do it again I'd probably go with leaving the std RB30 1.8mm restrictor up front.

All though I possibly believe the valve train noise was as a result of the head bloke not knowing what he was doing with the lifters as a result they trapped a little air inside.

So as they so do it right do it yourself. I've pulled the lifters apart; meticulously cleaned, primed and reassembled.

[xsv_32]

Im using th 25de (vvt). Ive been told i have two main options, one is to block the rear gallery all together but was told it can starve one end of the head during start up. Which isnt much of a trouble as it disappears once oil pressure is up but id rather go with the other option to just restrict both galleries using the tomei restrictors. Anyone else gone 4 this option?

[Cubes]

The VCT head has a total of 3 feeds.

How you restrict it depends on the oil pump your going to run.

[Sydneykid]

Im using th 25de (vvt). Ive been told i have two main options, one is to block the rear gallery all together but was told it can starve one end of the head during start up. Which isnt much of a trouble as it disappears once oil pressure is up but id rather go with the other option to just restrict both galleries using the tomei restrictors. Anyone else gone 4 this option?

Block the middle and use the front feed (the VCT one) and then restrict the rear feed according to the table.

Cheers

Gary

[Keeper]

where are the restrictors for sale???

[Craved]

tomei have the restrictors - think hi-octane in SYD have them too

though others have made their own from solid rod and a drill.

[r33_racer]

I posted about this before ages ago....you can use copper mig tips...just find the size that has the correct hole diameter you want and machine it down or cut it down to suit. Pretty sure most std mig tips are around a 1/4" OD.....actually i cant recall now...maybe it was about 7mm or 5/16"...either way it works

Edited August 7, 2008 by r33_racer

[inmate]

I am going to be using an RB25DE head without VVT.

Could I block the rear feed and use the RB30 1.8mm front restrictor without filling the catch can with too much blow by?

Car will be used for daily duties, towing & the odd 1/4 run

[Cubes]

You could and it would be fine.

However at this point in time, if I were to do it again I would restrict both down to 1.5mm and run a nice catch can setup that drains to the sump.

The drain to the sump also works to vent the bottom end as a result the oil is able to flow from the head back to the bottom end considerably easier.

All though mine has had no issues the top end is noticeably noisier since performing the oil restriction mod on first start up when cold.

[Dale FZ1]

If the cold start-up noise is somehow related to the elimination of the rear feed, I can see the logic in retaining both feeds.

Here's a variation on the theme, using the idea that a single 1.5mm restrictor otherwise supplies enough volume during operation:

MIG tips are available with a 1.2mm orifice. Cross sectional area - 1.13 sq.mm

SK's preference of 1.5mm restrictor provides cross sectional area of 1.77 sq.mm

Install 1.2mm restrictor front and rear gives ~ 2.25 sq.mm so slightly more flow than 1 x 1.5 but way less than 2 x 1.8 or 2.0mm as stock. Similar end result and maybe avoid the issues Cubes identified.

Could be wide of the mark and solely related to hydraulic lifters but worth raising.

Comments?

[Cubes]

Dale would the flow be reduced further again due to increased friction losses as a result of the smaller hole? In other words the cross sectional area is not 'directly' related to flow? i.e 2 sq.mm would not flow 2x that 1 sq.mm?

I have NFI when it comes to this but visualising flow through a smaller pipe suggests so.

A friend fitted 2 x 1.1's to his and it tapped its arse off. :S

[Dale FZ1]

I also have little idea of fluid dynamics, but the restrictor is just that - an orifice rather than a tube. So restriction would be causing the reduction in flow rather than friction I would think.

All the same I don't want too much in-depth analysis but threw up the idea given your start up noise. If it is lifter noise only then maybe not a problem. I've heard from more than one source that using a 10W60 oil is an important part of the equation of making this setup work optimally.

Interesting to hear that your mate with 2 x 1.1 restrictors had problems with noisy lifters.

So at the least it appears to be important to stick with SK's guide and go 1 x 1.5mm and a bung in the rear?

[Cubes]

Well... 10w60 next oil change it is then.

I'll let you know how it goes.

I should mention nothings broke with a little bit of noise on start up. Its now been a year since the turbo and restrictors have gone in and travelled a good 25k. There was no real wear on the lifters etc when I pulled them out recently to drop in a new set of cams.

[Dale FZ1]

Sticking with the general theme of the thread, who can share experiences regarding oil pump spec and restrictor sizes regarding lifter bleed out? Clearly this relates to 30/25 with a non-Neo head.

I'd presume very few of us would be running dedicated track cars with this setup, so quiet/smooth operation is still high on the list of priorities. ie. I want to avoid bleed out due to too much reduction in oil delivery to the top end.

My setup is

25DE oil pump (stock)

non VVT head

internal oil drain-backs in head + block drilled oversize to 9.5mm

restrictors 1.6mm (F) 1.2mm ®

and (hopefully) catch can with drain-to-sump

engine speed < 7000rpm

application: road, motorkhana, club sprint

Edited October 8, 2008 by Dale FZ1