Hey guys i know it's probly been cover at some point but i just can't find it has anyone done this modification and know where i can find a descent 90 fitting to use for this application. help me out guys i know some knows

Carl has this done to his motor (head)

zerothread?id=190419

Yeah, I did the dual lines too, they leaked with that type of fitting so I had to get these custom fittings from earl's that swivel in... I'm not sure If I trust them though. I might end up drawing a single drain in CAD and machining my own....

i recommend you to run braided lines and AN fittings.

I have a single -12AN fitting coming from mine.

Best bet is to get a 90* AN fitting tap or whatever the back of the head and run a line from it.

Matt owns/runs a shop in Japan building high HP motors - very high HP motors. This is long, but a good read:

If you're looking for soultions here, delete it because there are nosolutions for a fictional problem. It's going to be dripping withsarcasm, too! What fun. Hang on to your shorts.

That's right. You didn't read it wrong. The Internet spread BS onthis subject has finally reached "urban legend" status and I feelit's time to set the record straight, vent, shed some light,whatever. What pushed me over the edge is a new post on Hybrid Zwhere the guy (Boosted Z I think?) gets some good #'s on the dynobut sees oil pressure falling off around 8,000 rpm. The firstquestions asked are "Do you have the oil restrictor?" etc... sigh...Are you serious??? Now we've reached the point where the drain backissue is so bad that the engine can't even do ONE DYNO PULL withoutall five quarts of oil ending up "trapped" in the head?? Give me abreak, man.

What's funny is that the RB26 is, what, 18 years old, but it neverhad oil drain back issues until Tomei started selling the stupidrestrictor with a little hand drawn picture of high oil levelwithout the restrictor and low oil level with it. Actually, it's nota bad idea, but I'm calling it stupid because of what it started.

A little perspective:Obviously Nissan doesn't think it's a problem because they neveraddressed it in the 33 or 34 engines. Oil returns and pressureorifice are the same as far as I can tell. At least not any majorchanges for what seems to be a catastrauphic problem (sarcasm).Would someone PLEASE explain to me why Nissan can take a bone stockR32, R33, or R34 to the Nurburgring and go at full throttle, lapafter lap, eight plus minutes per lap and never have oil drain backproblems that rob the sump of oil, but a guy on an Internet forumcan't do one lap of a two minute circuit or even one dyno pull, haveoil pressure sag, and have everyone under the sun call out forrestrictors and additional drain backs? No, not really; that wasrhetorical.

I've seen N1 and Super Taikyu race engines up close and even inside.Never seen any additional drain backs. Not sure of the Super GTengines, but they probably use a dry sump with scavenge in the headand no drain backs, to keep oil off the crank. Saw the HKS Drag GT-Rup close too, and never noticed anything like that. There areprobably thousands of track GT-R's driven in Japan alone that don'thave this problem.

My experience:Power numbers's? Don't know. Our dyno's here won't hold much over700 without slipping tires (at least that's as high as I can getit), and I'm not a big fan of numbers on a piece of paper, so Ireally don't care. However, I can tell you that the most powerfulRB26 I've ever built burried a 320km/hr (198.838 mph and don't tellmy mom) speedo on the expressway at over 10,000 rpm. Modified HKSpump, no aftermarket restrictor, no additional drain backs, oilpressure holding at a rock-solid 115 psi.

In fact, I've never used an aftermarket restrictor or additionaldrain back in any engine I've ever built... I've never had an oilpressure problem in any RB engine. Ever. I build 'em loose, too.

Maybe some people are having problems. With the above, I doubt verymuch it's a "pooling in the head" problem.

Here's why:Suck air in the oil pump and oil pressure goes to zero almostinstantly. No "falling off in the top end". Some people shift gearsand the oil pressure is magically restored (even though all the oilis in the head), only to have it fall off again as soon as the rpm'sclimb back up.

Oil pressure falling off in the upper rev range can be caused byseveral things, the most common of which is cavitation. I would putmoney on it that most people running RB Z's are using the steel pansfrom the Z31? This not only eliminates the excelent RB26 sumpbaffeling, it also precludes you from using the RB26 windage trays.Foamy oil cavitates. What happens is tiny bubbles in the oil enterthe pump under huge vacuum. A bubble that already exists is mucheasier to expand into full blown cavitation than oil with nobubbles. The bubble(s) expand to many times their own size, takingup space originaly reserved for oil. Once it hits the pressure side,the bubble collapses, but the damage is done. Less oil went throughthe pump. The faster the pump spins, the more vacuum is created, andthe worse the problem becomes. Oil pressure that falls off as therevs climb is almost always caused by cavitation. This can also becaused by a too-small or too-restrictive oil pick up. Moving it allthe way to the back of the engine couldn't possible affect this,could it?

I watched a video of a guy going around the track in an RB Z. Onbraking and turning in only one direction the oil pressure wouldzero out almost instantly. Once the car straightened out or throttlewas restored, pressure jumps back to normal instantly. Once againthe common consensus was the 'ol PIHS (pooling in head syndrome). Ondecel or only turning in one direction? PIHS or bad baffeling in thepan/pick up location? You be the judge, but use common sense.

The restrictor is good:But for the wrong reasons. The right reason is the same as a smallChevy or any other engine for that matter... The head doesn't haveheavy rotational forces for two reasons: There's no heavy stuffswinging around, and it's only moving at half the crank speed. Itdoesn't need a lot of pressure, especially because the cam to lifterinterface is fed by oil dribbling out of the cam journals. Pressurein the head is wasted, which is the reason for the factoryrestricotr. A smaller restrictor will keep the pressure to thebottom end higher in the rev range due to decreased VOLUME wasted inthe head.

The additional return is bad:There are two large returns in the rear of the head and severalthroughout the length of the left side of the motor. Due to crankwindage, the ports on the left side of the engine are subjected to avacuum because the crank is pulling down on that side of the engine.The one in the rear, right supplies windage to the head for crankcase ventilation. Air doesn't pull down the left side if it can'tcome up the right. Under hard acceleration, oil wants to move to therear of the engine. Some people install a large line from the rearof the head back to the right side of the front sump in the GT-Rpan. Anyone see a problem with this? There's actually two. Under 1gof acceleration, not only will oil not move forward through thisline back to the front of the engine, it gives the oil in the sumpanother path to exit the sump. Reason #2 is that the right side ofthe engine is pressure side and not the suction side. Crank windageat higher RPM can push oil back into the tube if it's not verycarefully baffeled. It could work well in a rear sump if the hose isalmost straight down and entering the left side of the engine. Butthis as assuming there really is a drain back problem.

What I have seen/done:An additional line from the back of the head, under the plenum, backto the RADIATOR. Additional coolant movement out of the head. Verycommon mod on drag engines. Maybe someone saw this somewhere andmistakenly thought it was for oil and ran with it? Who knows.

With the additional oil restrictor in place, the oil level in thehed would certainly be lower than without it, but I assure you thateven with the stock restrictor, it's not even close to a problem.Especially not the problem it's been made out to be.

Anyway. I feel better and will now step off of my soap box. I'm surethere will be arguments from people who had PIHS cured by thesemods, or whatever, but you really need to stop and think about it.Especially given the factory stock cars not having problems on thering, etc.

Matt

Yea, its a on going debate over on FA.

Anyways, what is it? $50 for a simple return setup? 2 fittings and a hose?

Even if it does nothing but offer a slight sence of security/assurance than I say that $50 odd are worth it.

if thats matt at motorworx then he most certianly knows his stuff...

Carl H wrote:if thats matt at motorworx then he most certianly knows his stuff...

Carl does your oil pressure drop up top at 8000rpms?

Carl H wrote:if thats matt at motorworx then he most certianly knows his stuff...

Yep he does.

should probably argue this with someone who's built 30+ gtr circuit cars who HAD excess oil in the head. it does exist

http://www.skylinesaustralia.c....html

sydneykid ftw