Oil Control In Rb's For Circuit Drag Or Drift

[bubba]

This is getting mighty confusing..

Setup: R32 RB25DE head, stock cams, hydraulic lifters, RB30 block etc, N1 pump.

I wasn't running any restrictors, and didn't have the head vent/drain plumbed up (even though I have a fitting there for it). Was having problems when spending too much time up around 6000rpm (sideways skidpan/track stuff), oil was collecting in the head then getting sucked through the valve stem seals on overrun. Normal spirited driving was fine. Catch can setup was blocked PCV, both cam cover breathers to atmo breathing catchcan.

Now with my engine on the stand, I was looking to run a 1.5mm restrictor up front and block the back (not so sure now after what Cubes(SLAPS) said). I was also going to plumb the head drain/vent to the exhaust side of the sump and was considering a vent from the intake side (probably dipstick as it just seems a lot easier) to the catchcan, along with the two cam cover breathers. PCV obviously remaining blocked.

I am also going to get the oil returns in the block enlarged but not too clear on where/which ones.. there are two large returns at the back yes? and 3 on the exhaust side of the block? how much do people take this out by?

Am I on the right track?

Is there anything else I should be doing?

What is this chamfering of oil galleries people talk of? (I know what chamfering is, but what galleries? and to what extent?)

Sorry for all the questions but D-Day is fast approaching!!

[Swiper the Fox]

This is getting mighty confusing..

Setup: R32 RB25DE head, stock cams, hydraulic lifters, RB30 block etc, N1 pump.

I wasn't running any restrictors, and didn't have the head vent/drain plumbed up (even though I have a fitting there for it). Was having problems when spending too much time up around 6000rpm (sideways skidpan/track stuff), oil was collecting in the head then getting sucked through the valve stem seals on overrun. Normal spirited driving was fine. Catch can setup was blocked PCV, both cam cover breathers to atmo breathing catchcan.

Now with my engine on the stand, I was looking to run a 1.5mm restrictor up front and block the back (not so sure now after what Cubes(SLAPS) said). I was also going to plumb the head drain/vent to the exhaust side of the sump and was considering a vent from the intake side (probably dipstick as it just seems a lot easier) to the catchcan, along with the two cam cover breathers. PCV obviously remaining blocked.

I am also going to get the oil returns in the block enlarged but not too clear on where/which ones.. there are two large returns at the back yes? and 3 on the exhaust side of the block? how much do people take this out by?

Am I on the right track?

Is there anything else I should be doing?

What is this chamfering of oil galleries people talk of? (I know what chamfering is, but what galleries? and to what extent?)

Sorry for all the questions but D-Day is fast approaching!!

I wouldn't recommend blocking the oil feeds if its a 25 head...it feeds your lifters. You can run it to the exhaust side but under boost it will be filling the back of the head with oil as we have seen quite an alarming amount of oil travelling from the sump up this hose under boost along with crankcase pressure. The hose will only allow a small amount of oil to drain as when not under boost when it can actually travel to the sump. As you have seen the oil at the rear of the head has to travel over the top of the two large rear factory drains into the small hole in your fitting then travel forward of this point against g forces to enter the sump. Take the factory drains out 2mm on each and if you are keen match the head and block rear drains to the headgasket.

Slaps is Cubes eh...lol.

Edited September 21, 2009 by DiRTgarage

[bubba]

I wouldn't recommend blocking the oil feeds if its a 25 head...it feeds your lifters. You can run it to the exhaust side but under boost it will be filling the back of the head with oil as we have seen quite an alarming amount of oil travelling from the sump up this hose under boost along with crankcase pressure. The hose will only allow a small amount of oil to drain as when not under boost when it can actually travel to the sump. As you have seen the oil at the rear of the head has to travel over the top of the two large rear factory drains into the small hole in your fitting then travel forward of this point against g forces to enter the sump. Take the factory drains out 2mm on each and if you are keen match the head and block rear drains to the headgasket.

Slaps is Cubes eh...lol.

Thanks for the reply, just to clarify a few things:

So plumbing the dipstick to the catchcan is enough ventilation? would plumbing the hose from the back of the head to elsewhere (intake side at the top of the sump extension?) be of any benefit?

As for the factory drains, is that 1mm either side?

Cheers!

[Swiper the Fox]

Thanks for the reply, just to clarify a few things:

So plumbing the dipstick to the catchcan is enough ventilation? would plumbing the hose from the back of the head to elsewhere (intake side at the top of the sump extension?) be of any benefit?

As for the factory drains, is that 1mm either side?

Cheers!

no i wouldnt use the dipstick id put a larger -10 hose where you suggested (intake side at the top of the sump 'wing')...thats exactly where i have mine.

yes 1mm either side...2mm in total.

[bubba]

Thanks Dirt

[DRIFTER]

Contamination, from what? Condensed water vapour? It boils off with the right oil temperature. Dust? I have a filter on my catch can breather. Ditrty cacth can? I don't think so. So what contamination are they talking about?

BTW I don't change engine oil after every race meeting. I used to many years ago, but then I sent samples to Castrol Technical for testing and they came back with perfect reports after 1, 2 and 3 race meetings. Especailly now that I'm using ethanol which, with its lower vapourisation temperature, doesn't contaminate the oil like petrol does. As per above, water boils off, so if the engine is in good condition, which I confirm with regular leak down tests, there is no need to waste 10 litres of oil 8 times a year.

Cheers

Gary

does anyone know the contact details to get an oil test done? what does it cost to test oil?

[Beer Baron]

http://www.oilsols.com/contact.html

http://www.hotfrog.com.au/Products/Oil-analysis

[DRIFTER]

thanks.

[PRO_32]

Just a quick question.

Im looking into a crancase evac setup into my exhaust, Now most of the kits i've seen and info ive read for that matter say to set it up from the breathers on the rocker covers to the exhaust via a check valve but to me it sounds wrong, It would seem that the sump would remain pressurised and a partial vacuum would be created in the head tottally defeating the purpose (making it even more difficult for oil to flow down the returns.

Im going to weld a fitting (or two) onto the sump running into a small oil/air seperator (like the ones found on air compressor's) then into the exhaust via a one way valve.

I would also have the breathers from the cam covers venting to atmo via a baffled catch can.

Im hoping for a partial vacuum in the sump whilst maintaing positive pressure in the head hopefully aiding oil to be (pulled) down back into the sump..

Am i missing something or doeas it sound about right?

I have actually read this whole thread (while ago ) and remember this being touched on but dont remember what page(s) and it's painfull going through it all on an iphone so any info appreciated.

Cheers

[XRATED]

does anyone know the contact details to get an oil test done? what does it cost to test oil?

Any diesel mech company can supply sample kits.. 40 odd bucks a pop.

[simpletool]

well this is all very interesting.

porche figured this out with the 924 turbo.. with a factory oil air seperator then off to the breather pipe. nismo has a oil air seperator for the gtr that t's into the rear turbo drain to return the oil with the air continuing on to the rear breather.

Anybody double up the turbo oil return line as breather (to atmosphere) - could be handy to prevent pressure build up preventing oil flow through turbo ?

Also, I can't help but think that this oil retention in the head issue is made worse when using higher viscosity oils. My thoughts are that because of shear thinning of the oil when going through the oil pump the thicker oil affects draining more than pumping. Nissan specifies a 30w oil, where the ratio to draining and pumping effort is higher than a 50w oil. Occurred to me the other day. This is a bit of a moot point obviously since high rev, higher blow-by engines are going to require some sort of oil modifications for track use anyway. And you can't use 30w oil for high loads.

Edited October 1, 2009 by simpletool

[natoe aka slw 031]

ive almost finished building my 25/30 in the end I blocked the rear oil gallery and used a 1.5mm restrictor in the front.

ive welded a fitting on the sump for the stock head drain. I had my mate whose a fitter and turner make up a fitting for the back of the head to go over the old welsh plug.. all i had to do was tap a thread either side of the welsh plug put a bit of gasket goo around it. we welded another fitting on the sump for this drain/ vent. fingers crossed it should be sufficent!

if anyone else wants a head drain send me a pm. he said he will make more rear head drains for $120 each..

ill chuck some pics up if anyones keen

[Simonster]

I wouldn't recommend blocking the oil feeds if its a 25 head...it feeds your lifters. You can run it to the exhaust side but under boost it will be filling the back of the head with oil as we have seen quite an alarming amount of oil travelling from the sump up this hose under boost along with crankcase pressure. The hose will only allow a small amount of oil to drain as when not under boost when it can actually travel to the sump. As you have seen the oil at the rear of the head has to travel over the top of the two large rear factory drains into the small hole in your fitting then travel forward of this point against g forces to enter the sump. Take the factory drains out 2mm on each and if you are keen match the head and block rear drains to the headgasket.

Slaps is Cubes eh...lol.

Just an aside- I have a 25 and have the rear set of oil feeds blocked off, have had no problems after around 13000km and hard track driving.

I use an catch can that flow back into the sump

[steeldawg_69]

Great post!! Good arguments on both sides. After this read I'll be going Sydneykid's route.

[tufrx3]

Great post!! Good arguments on both sides. After this read I'll be going Sydneykid's route.

I have oil drain fittings for the back of the head if you need it. Have them in a dash 8 or dash 10 size. (dash 8 is preferred)

[SLAPS]

Slaps...trying to belittle people who are trying to help on here by calling them childish names does very little. Grow up.

Sorry bud my post was a little misleading.

I wasn't calling you a grease-monkey but referring back to comments made many years ago.

Edited December 1, 2009 by SLAPS

[Swiper the Fox]

Sorry bud my post was a little misleading.

I wasn't calling you a grease-monkey but referring back to comments made many years ago.

Yeah Cubes decided it was mature to PM me calling me a grease monkey (he has no idea of who i am or what i do) then boasting how he was a lawyer or in law school. All this tirade after all i did was point out the group buy he was running was in doubt as i knew the parts he was offering were unavailable as one of my suppliers had them on back order for 6 weeks. He then trawls the site and finds a post where i had a crack at SK and issues me with a warning to get back at me. He's a good thing gone as far as im concerned.

cheers for clearing that up Slaps.

[MBS206]

Okay need some quick help, as I've been so damn confused through this thread trying to work out who breaths what where...

I have the point in the back of the head to breath, which side of the sump does it go to (Driver, or passenger) above or below oil line?

return drain from my first catch can, return to driver or passenger, above or below oil line?

Also, the stock RB25DET has an oil drain off the front passenger side that normally returns to the block, on an RB30DET, no provision for this, how should this drain be ran to the sump (Passenger side obviously) but above or below oil line?

[Swiper the Fox]

Okay need some quick help, as I've been so damn confused through this thread trying to work out who breaths what where...

I have the point in the back of the head to breath, which side of the sump does it go to (Driver, or passenger) above or below oil line?

return drain from my first catch can, return to driver or passenger, above or below oil line?

Also, the stock RB25DET has an oil drain off the front passenger side that normally returns to the block, on an RB30DET, no provision for this, how should this drain be ran to the sump (Passenger side obviously) but above or below oil line?

You can tee into the intermediate tank return line to breathe the rear of the head...top of sump on drivers side as high on the sump as possible....i use -10 for my sump to intermediate tank line...works well...no need for the rear head fitting if set-up correctly.

Edited December 1, 2009 by DiRTgarage

[MBS206]

You can tee into the intermediate tank return line to breathe the rear of the head...top of sump on drivers side as high on the sump as possible....i use -10 for my sump to intermediate tank line...works well...no need for the rear head fitting if set-up correctly.

See... Lost again... You say to tee the breather from the rear of head... But not to use it at the end of the paragraph... :S

So drivers side as high as possible for rear of head to remove the positive pressure from the sump?