Jump to content
SAU Community

Recommended Posts

120psi is fine. That is a rough guide of what it will be. But as said that can change depending on main, rod and rod side clearances used in conjunction with what viscosity oil is run. You might find hot you will only achieve 100psi. Stop worrying about the oil pressure and have the oil squirters put back in.

Your engine builder should know that system pressure is controlled via bypass and by grub screwing the oil squirters he is only reducing a fraction of the pumps potential supply volume, not pressure. Your bypass may open sooner without the squirters now, assuming everything else being the same.

Forget the head oil problem by running high pressure, if you have small 1.0mm-1.2mm restrictors and head drains opened up and adequate crankcase ventilation to a breather can you will be fine in that regard.

  • Replies 58
  • Created
  • Last Reply

Top Posters In This Topic

So the guys using non A8 blocks for there rb30/25 would be running no oil squirters? What's the difference between non in a rb30 and none in a rb25???

Assuming some use the non A8 block not to sure what block they use for the 30/25 build

The vl turbo block doesn't have squirters either

Really? I was always under the impression they did.

Running oil squirters is a big advantage to not using them.

They help to cool the pistons and lubricate the bores. Pulling them out is a step back wards.

Yes correct, people who turbo RB30E's do not have oil squirters but if they did the user or engine builder wouldnt go removing them.

Being a parrallel thread I'd like to see how he securely grub screwed the gallery without just banging a grub in there and blocking off the gallery internally. It can be done obviously but wonder if he went to the effort. I think the thread goes well into the gallery from memory.

I vaguely remember those squirters coming off the main internal gallery that feeds the crank??

Be interesting if his put grub screws in the squirter holes and restricted the main artery with them.....

You'll have great oil pressure then... Not much to the bearings though.

Being a parrallel thread I'd like to see how he securely grub screwed the gallery without just banging a grub in there and blocking off the gallery internally. It can be done obviously but wonder if he went to the effort. I think the thread goes well into the gallery from memory.

I vaguely remember those squirters coming off the main internal gallery that feeds the crank??

Be interesting if his put grub screws in the squirter holes and restricted the main artery with them.....

You'll have great oil pressure then... Not much to the bearings though.

I can't comment on how he went about the grub screw but when I showed up with my nitto pump and it been 120psi he did mention about putting the squirters back in, but then he ended up playing with the springs to set the psi

So if rb30 blocks don't have oil squirters what is the diffence between a rb30 without squirters to a rb25 with squirters, yes I know rb25 came out with the squirters so lodgic says it should stay there but in this case it's not, just trying to see the points on why the rb25 has the squirters to cool pistons down and to lube the bore, but a rb30 doesn't, so wouldn't a rb30 have problems?

Rb30 is an older tech motor. So the newer version ie: rb25, nissan engineers decided to use oil squirters to keep piston temps in check.

People want the extra torque from rb30's which is fine but they must be built accordingly. So larger tolerances to allow for extra alloy piston expansion etc. or coating the piston tops

*sigh*

Pressure is restrciction to flow.

Think about a garden hose with no end on it, water runs out. Put your finger over the end (i.e make a restriction) and the water shoots out at a higher pressure

More pressure often equals less flow, but its not that simple as in they are not directly proportional (from memory). But at no flow you would hit the pumps relief setting so you would get maximum pressure at minimum/no flow

And the flow is determine by how much pressure? More pressure more flow?

yes and no. Different pump designs, oil viscosity, temp etc will dictate the flow rate at a given pressure...essentially it's the same principle as aftermarket turbo's, the airflow @6psi on a stock turbo can be totally different to the airflow @6psi on an aftermarket turbo

And just to add to the rest of the conversation, does an n1/oem oil pump operate at ~120psi (8bar) at redline?

Edited by wedge_r34gtr

Different pump designs - positive diplacement and centrifugal need to be thought of differently.

Unlike a centrifugal pump a positive displacement pump's speed is the sole arbiter of its output. It will pump a certain amount of fluid (oil in our case) per revolution almost irrespective of the pressure it is pumping against. However, different pumps give you different amounts of oil because their gear designs are different. Obviously a smaller pump will move less oil per revolution by design.

What happens to the pumps output is dictated by the pressure relief arrangement and the engine design (bearings clearances, oil galleries etc). The oil can only go in one of two directions - out the relief or through the engine. The lower the relief spring constant and seat force (which are added, obviously) the more oil goes through the relief side of the pump and the less goes through the motor. By increasing the pressure relief on the pump you force more oil through the motor.

It is difficult to compare to turbos because the waste gate functions in an analagous manner to the pressure relief device on an oil pump save for the fact it is on the turbine not the compressor

yes and no. Different pump designs, oil viscosity, temp etc will dictate the flow rate at a given pressure...essentially it's the same principle as aftermarket turbo's, the airflow @6psi on a stock turbo can be totally different to the airflow @6psi on an aftermarket turbo

And just to add to the rest of the conversation, does an n1/oem oil pump operate at ~120psi (8bar) at redline?

not completely true. Its different to air.

Pressure IS pressure, it dont matter if your pump flows 8KL at redline if you have a certain size restriction, with same oil, and same pressure, the flow will be identical. The only time flow of pump counts is at idle when relief valve is shut. If both are set to certain pressure both will move the exact same at full revs.

Having one at 75 and one at 70 psi the higher pressure does mean more oil flow, through pressure, not pump capacity. If this makes sense

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×
×
  • Create New...