Rb26 oil head return drilling

[GarettH]

Hey guys after my engine already being built balanced etc.. I've been reading on drilling the head/block oil returns. I have tried searching and read through 30 pages or so on the rb oiling sticky. I'm trying to combat all oil issues so its never a problem, currently my bottom end consists of a brand new r34 crank, cp pistons, eagle rods, journals line honed, cosworth bearings, greddy trust extended sump, tomei 1.2mm head restriction, ati dampner.

And still researching if i should do the head drain to sump or just vent the sump via catch can. My main question is if i drill out the oil return galleries will i need to have everything cleaned, hot tanked again etc...

[GTSBoy]

At this point I would suggest merely putting in sufficient external sump breathing.  Opening up the oil drains only buys you a small amount of extra breathing room.  I suspect that a decent sump vent (which basically bypasses the sump gas flow around the oil returns) is a much more significant change.

And half the reason for saying the above is because.....yes, you would need to clean all the swarf out after drilling the drains.

[GarettH]

45 minutes ago, GTSBoy said:

At this point I would suggest merely putting in sufficient external sump breathing.  Opening up the oil drains only buys you a small amount of extra breathing room.  I suspect that a decent sump vent (which basically bypasses the sump gas flow around the oil returns) is a much more significant change.

And half the reason for saying the above is because.....yes, you would need to clean all the swarf out after drilling the drains.

Ah that's to bad, but i figured that anyways. I think for me the r34 crank/ tomei pump/ head oil restriction/ extended/baffled sump and once I figure out a sump vent that I should be pretty covered for my needs. My 100% unopened rb26 made 622whp@19 psi, looking for 800ish now and not reving past 8000. And only street driven/few races a year and only 1 or 2 1/4 Mile days.

 

Do you have any recommendation on a sump vent setup? There were no diagrams or such in the oiling thread. or is it simply just PCV-Valve Covers- Catch Can and then returned to sump?

[iruvyouskyrine]

Keep reading mate, i summarised the entire 'oil control' thread about a year and a half ago now. I wrote a very easy to follow how-to post with tables and diagrams.

If you are still thinking a 'head drain' is the go then you haven't got far enough yet. 

[iruvyouskyrine]

Here is the link for you

[hardsteppa]

12 hours ago, GarettH said:

. My main question is if i drill out the oil return galleries will i need to have everything cleaned, hot tanked again etc...

 

I just had this on my rb25 head, one return drain hadn't been drilled out fully from factory so I finished drilling it through while the head was off. All I can say is - you will need to remove all welch plugs and cold tank/fully clean out head if you do any machining. I detergent-bathed it twice, rinsed it, compressed air and vacuum-cleaned all galleries, chemical-cleaned it and compressed air cleaned it again, and still had some small bits of aluminium swarf and frag stuck in there, luckily no harm done.

[GarettH]

Keep reading mate, i summarised the entire 'oil control' thread about a year and a half ago now. I wrote a very easy to follow how-to post with tables and diagrams.

If you are still thinking a 'head drain' is the go then you haven't got far enough yet. 

Thanks for the link its a very good read and answered my question about venting the sump. As for the head drain i was referring to drilling out the return galleries not the external head drain kit. As stated i already have r34 crank, tomei oil pump, oil supply restrictor and extended sump. Ill just vent the sump now

[GarettH]

I just had this on my rb25 head, one return drain hadn't been drilled out fully from factory so I finished drilling it through while the head was off. All I can say is - you will need to remove all welch plugs and cold tank/fully clean out head if you do any machining. I detergent-bathed it twice, rinsed it, compressed air and vacuum-cleaned all galleries, chemical-cleaned it and compressed air cleaned it again, and still had some small bits of aluminium swarf and frag stuck in there, luckily no harm done.

Thanks for the reply! I think ill just have to pass on drilling the oil returns out for now. I read RIPZ from NZ has actually never even drilled his returns out.

[KiwiRS4T]

Restrictors and sump vent will do more to help.

[Shoota_77]

If you've got the time and the inclination do it all.  None of the recommended measures are detrimental to anything else (apart from the head to sump vent being a pain for heater hoses) so do everything you possibly can while the engine is out of the car.  Once it's back in it's too late.

If you're interested here is what I did with my head and block while mine was all apart (start at page 3 if it doesn't go straight there)- 

 

[djr81]

On ‎31‎/‎08‎/‎2016 at 4:41 AM, GarettH said:

 

Hey guys after my engine already being built balanced etc.. I've been reading on drilling the head/block oil returns. I have tried searching and read through 30 pages or so on the rb oiling sticky. I'm trying to combat all oil issues so its never a problem, currently my bottom end consists of a brand new r34 crank, cp pistons, eagle rods, journals line honed, cosworth bearings, greddy trust extended sump, tomei 1.2mm head restriction, ati dampner.

And still researching if i should do the head drain to sump or just vent the sump via catch can. My main question is if i drill out the oil return galleries will i need to have everything cleaned, hot tanked again etc...

 

As noted most of these measures are not a case of either/or.  You need them all to work together to try and overcome a design floor in the RB26.

So, yes, drill the oil returns.

Vent the sump via the catch can.

Fit a restrictor.

But most importantly pay alot of attention on your piston and ring selection, how they are assembled in terms of clearances and overwhelmingly important how they are lubricated during assembly (The bores/rings) and how you load the engine immediately after start up.

The less blowby you have the less of a problem you will have with oil.  There is a reason the fat old school cast iron rings Nissan put in the engines work better than the steel aftermarket ones.