Wat Oil Pump Should I Use On My Twin Turbo 26/30

[R31Nismoid]

r33_racers post does explain his view with pressure in relation to motor clearance etc

Aside from that - Drag cars are not neccesarily a good example. You rarely would take a 8/9 sec drag car up into the hills for a 10min squirt on a Sunday

This is what daily drivers tend to do, it's certainly closer to track than it is to drag IMO (when you talk about a daily/street car), because lets face it - Nothing more entertaining than a nice bendy piece of road in a GTR/Skyline.

10 seconds is not the same as 10 mins. This is where oil pressure is certainly as important, if not more so.

You'd need to talk with your engine builder and workout what the desired oil pressure should be in relation to use of the car, and the assembly of the motor itself.

[r33_racer]

R31Nismoid is right in that its more application/motor setup specific. That last post I was being quite negative about it and didnt quite explain everything properly. Ill try to do it now as best as i can.

The usual rule is fine if your revs are kept to around standard. When you start going high with them, say 7000rpm and upwards you generally need higher pressures. This is due to the poor design of the nissan cranks oiling system. The crankshaft utilises cross drilled mains and big ends inorder to feed oil to the rods. With this design, as the revs climb so does the centrifugal force which acts against the oil. I think I read somewhere that this force starts to have an impact on the oil feed once you get over 5000-6000rpm. What happens is the oil starts to seperate and froth/foam up inside the crank as oil pressure is trying to send it to the big end, but the centrifugal force is trying to send it back to the main journal.

Since pump manufacturers needs to cover bases for all setups in one hit they make the pump capable of the worst case scenario. I can only assume thats why Nitto have two springs, one for 70psi and the other for 120psi. Now if you are building a wild high reving engine, then you would need the higher spring pressure to make sure you have more oil pressure then centrifugal force acting against it so your big ends dont suffer oil starvation. The unfortunate part of a cross drilled crank is that the only way to overcome that force is by increased oil pressure. The ideal crank oil system is a straight shoot gallery. You can find this on pretty well any v8 crankshaft. Its just one hole that goes from your main journal to the big end journal and with this style you dont need big oil pressure as it doesnt have anywhere near as much centrifugal force acting against it.

But everything plays a part in oiling system setup, main and big end clearances, conrod side clearance, oil viscosity choice and oil hole sizes in your block and crankshaft. There are probably more variables that make an impact on this setup too that I havent listed. Now the obvious drawbacks are what I spelled out last time in that post ages ago. However, in the perfect setup, everything would be worked out so you would only run just the right amount of oil pressure for your setup(revs, clearances blah blah) and nothing would be in excess so you have minimal negatives/losses.

Hopefully that makes enough sense and anyone with a better understanding please feel free to clarify any of my errors

[BoostdR]

120 psi at 3000rpm thats way to much the pump should have two springs in the bottom where the nut is. remove the smaller one and it will drop to about 70 psi at full nosie but you do have to remove the sump

Totally agree. Have to do the same thing. Have a Reinmax pump running 8bar above 3000rpm. Will aim for 80-85psi max

Stock is 4bar

N1 is 5bar

Matt

Edited January 16, 2011 by BoostdR

[BoostdR]

sorry to bring up an old thread, but im trying to get my head around the whole oil pressure deal with rbs. i get that the aftermarket pumps may have better quality components, but as r33_racer states theres no need for extra pressure. so why is every1 so keen on really high oil pressure?? i understand for track cars u want all the pressure u can, but im talking street driven and occassional track work. my understanding of the topic is not great but ive ot this far.

the rb twin cams have a big problem with oil return from the head so oil restrictors are used. but how do you know what the restrictor size should be with such various oil pressures?? my understanding is the components of the head require a certain amount of litres/min of oil to prevent wear. does anyone know how much this is?? cos this would be the key factor in working out what size restrictor to use. different pressures will give different amounts of oil through the same restrictors, so can somebody expalin how they came up with the restrictor sizes and at what oil pressure they were used??

so then we look at the requirements of the bottom end. the rb30 bottom end is propably the most used and abused 6cyl engine in this country. there are literally 100s of single cam 30s built over the last decade punching out 8s, 9s, 10s, 11s as well as ridiculus burnouts all running stock rb30 oil pumps. but you dont hear about many if any failures.

so this being the case why such high oil pressure?? wouldnt all this extra pressure thats going to waste just wear out the pump faster???

Yes! a good point here regarding restrictors, they will flow varied amounts proportional to oil pressure. So they -all- need to be changed to reflect your pump pressure.

Not sure why CRD made this comment because it doesn't hold true for a higher pressure pump. I can understand it is rarely an issue however---the head is much more sensitive

"Hey Waza_GTR

Turbos normally have a 0.8 - 1.0mm oil restrictor in them restricting oil flow / pressure through them so this should not have been a drama.

What turbos were they?"

I had a long chat with Keir at Willall regarding this exact issue. To run a higher pressure higher flow pump 7bar or above the head restrictor needs to be 1.2mm in an RB26. Granted the turbo's are less sensitive to this issue but some can have induced turbine ring leakage with increased oil pressure and no other change. Some cases require a regulator or a modified turbo oil line restrictor. The turbo oil feed banjo bolt from the block has one...also the turbo inlet on the ball bearing cartridge turbo's should have a .85mm restrictor fitted.

So high pressure is fine. Just get your restrictors right

or

Reduce the pressure and use the std turbo restrictors and tomei 1.5mm block restrictor( for over 4bar and track use)

*of note the MInes triple flow cam baffles don't do a great job of returning oil to the head after it gets in the baffles. If you have to much oil in the head from the wrong restrictor and pressure these will make the problem worse. The std items have drain back provisioned.

Matt

[Raysboostin]

Thanks for clearing that up guys! very helpful! i still have a few questions though. if the high oil pressure is required due to poor crank oiling, is it the same story for aftermarket cranks?? or have these issues been addressed??

is there a rough way to work out what grade of oil you should be using at a given pressure to ensure ur not making the foaming of the oil worse??