Jump to content
SAU Community

Recommended Posts

heres a interesting catch setup. The car belongs to a tuner here in Tas.

I wont go into all the specs, but its a 25, 8500rpm, nitto pump, 11L sump .85 restrictor in the rear and I think 1.5 in the front enlarged oil returns etc, he does run the rear -12 drain on the rear of the head and said he found it did... not very much. hydraulic lifter still.

anyways just thought I'd put up a pic as I found it pretty interesting (sorry if no one else does!)

post-47373-1269327402_thumb.jpg

heres a interesting catch setup. The car belongs to a tuner here in Tas.

I wont go into all the specs, but its a 25, 8500rpm, nitto pump, 11L sump .85 restrictor in the rear and I think 1.5 in the front enlarged oil returns etc, he does run the rear -12 drain on the rear of the head and said he found it did... not very much. hydraulic lifter still.

anyways just thought I'd put up a pic as I found it pretty interesting (sorry if no one else does!)

Ha! I like his 'recirc' idea by putting the little K&N in with the main Airfilter.. haven't seen that before

heres a interesting catch setup. The car belongs to a tuner here in Tas.

I wont go into all the specs, but its a 25, 8500rpm, nitto pump, 11L sump .85 restrictor in the rear and I think 1.5 in the front enlarged oil returns etc, he does run the rear -12 drain on the rear of the head and said he found it did... not very much. hydraulic lifter still.

anyways just thought I'd put up a pic as I found it pretty interesting (sorry if no one else does!)

Ha! I like his 'recirc' idea by putting the little K&N in with the main Airfilter.. haven't seen that before

heres a interesting catch setup. The car belongs to a tuner here in Tas.

I wont go into all the specs, but its a 25, 8500rpm, nitto pump, 11L sump .85 restrictor in the rear and I think 1.5 in the front enlarged oil returns etc, he does run the rear -12 drain on the rear of the head and said he found it did... not very much. hydraulic lifter still.

anyways just thought I'd put up a pic as I found it pretty interesting (sorry if no one else does!)

the drain back to the passenger side rocker cover needs to be lower...otherwise a good set-up.

bingo on the rear head fitting...it does fu(k all except vent air under boost.

  • 4 weeks later...
On the circuit race cars we take a 5 step approach in controlling the amount of oil that is trapped in the cylinder head and/or blown into the catch can; :)

1.Block off one oil feed in the block (RB26’s have this standard)

2.Fit an appropriately sized restrictor to the other feed. The size of the oil pump is one of the determinates for the size of the restrictor, ie; a high flow, high pressure pump needs a smaller restrictor. Constant higher RPM needs a smaller restrictor etc.

3. Fit an external oil return from the rear of the cylinder head to the sump

4. Drill out the oil return galleries in the head and block

5. Machine around the oil return galleries to facilitate access for the oil

i know ppl will say call workshop..

but before i can, just wondering what to budget to do all the above modifications to my rb25det??

if anyone has paid to get it done let me know how much it set u back..

as i had oil coming out of my breather after a grip day..

and i mean 600ml worth of oil...

cheers

First attempt at a table;

Drag ----------------------------------- 1 mm, Block off, ------------------------------ 1.25 mm, Block off, ------------------------------ Leave, Block off, 1.25 mm,

Circuit/Drift ------------------------------ 1 mm, Block off, ------------------------------ 1 mm, Block off, ------------------------------ Leave, Block off, 1 mm,

Is that information for dedicated track / drag cars? Or is it fine for a street car making over 350kw that sees a track / strip every once a while and sometimes a bit of high rpm in other places :happy:

  • 2 months later...

Wow interesting read for sure.

I think something that will clear it up is to remember its not about vacuum its about high and low pressure. Air will always try to go from a high pressure to a lower pressure. Remember this is how the piston is pushed down the cylinder. So at any given moment if the air pressure is higher in the crankcase than in the exhaust then it will flow towards the exhaust. Upside of lowering the crankcase pressure is the pressure differential between the crankcase and the piston just got larger. free power not much but still free

I also read about dipsticks flying out etc mmm sorry the area being worked on in a dipstick tube is tiny and so its hard for it to make the load required to actually blow it out, if you have x amount of psi in the crank cases and then the dipstick equals 1/10th of a square inch then the pressure on the dipstick is x amount of pounds divided by 10.

Here is what I will be trying in my setup. 30/26

A catch can, breather bottle taken from the top of the rocker covers. One from the sump taken from well above the oil level.

I then plan on using a one way vacuum fitting into the exhaust to help pull a low pressure into the breather bottle.

The rocker covers will get an uprated baffling as well as a 1.5 mm restrictor in the front of the block and a total block on the back. normal cleaning up of oil galleries etc

Im always interested on feedback in case I have over looked something

Edited by waxracing
  • 2 weeks later...

Hi Guy's,

Let me start by saying I have read this thread right through and it's been full of great idea's, a lot of which I have already implemented but I'm still having major issues and I think I'm at the stage where I am looking at reverting to a standard oil pump unless I can think of a solution. I will outline my setup and what I've already done in the hope that someone may think of something that I have not tried.

My setup- R33 Gtst, engine is about 4000Klm's old (half that on the bloody dyno it seems) 25/30 VVT 340RWKW @ 15 PSI with GT35Riw, hydraulic lifters, rebuilt with the standard Nissan bearing clearances, dash 10 rear head mod going to sump on inlet side, VVT oil feed untouched, front oil feed blocked, rear oil feed fitted with 1.5mm restrictor. It also runs Castrol edge 10/60W and has a high volume gated sump. The oil return galleries are untouched (unfortunately) and worst of all its seems, an N1 oil pump is installed.

On the street cruising around is fine, the thing runs great and pulls like a steam train but every time I go near a race track it tries to push all of the oil out of it, in a real hurry too! In my last diagnostic testing I removed the catch can setup and have the three breathers from the rocker covers running into a huge open bottle to try and take any breathing restrictions out of the equation. It STILL wants to push oil out after a bit of sustained high rpm high gear runs. Two laps of Sandown saw about 2 litres come out...don't ask where :bunny:

Lets talk oil pressure. From memory the factory manual for an RB30 tells me it should have about 65psi @ 4000 rpm. I always thought about 10 PSI for every 1000rpm plus base pressure of 20ish PSI was about right. This should mean I should have about 30psi @ idle and roughly 85psi @ 6500rpm. What I see is about 85psi @ idle and then it quickly gets to 110psi @ around 3000rpm and then slowly creeps to over 120psi @ 6500rpm........seems way too high!

What else can I do taking in account the above mods already completed? Am I right in thinking a pump change is next? Maybe I have a dud oil pump and the pressure relief valve is not working correctly? Is my next move to change the pump back to standard? Should I take the N1 pump out and mod it for better pressure relief? It looks like I need to take the engine out to do a oil pump swap, is this correct or can it be done with the engine still in?

AHHHHHHHHHHH!!!! ............to say this is frustrating is an understatement. I hope someone can help.

Cheers

Hi Guy's,

Let me start by saying I have read this thread right through and it's been full of great idea's, a lot of which I have already implemented but I'm still having major issues and I think I'm at the stage where I am looking at reverting to a standard oil pump unless I can think of a solution. I will outline my setup and what I've already done in the hope that someone may think of something that I have not tried.

My setup- R33 Gtst, engine is about 4000Klm's old (half that on the bloody dyno it seems) 25/30 VVT 340RWKW @ 15 PSI with GT35Riw, hydraulic lifters, rebuilt with the standard Nissan bearing clearances, dash 10 rear head mod going to sump on inlet side, VVT oil feed untouched, front oil feed blocked, rear oil feed fitted with 1.5mm restrictor. It also runs Castrol edge 10/60W and has a high volume gated sump. The oil return galleries are untouched (unfortunately) and worst of all its seems, an N1 oil pump is installed.

On the street cruising around is fine, the thing runs great and pulls like a steam train but every time I go near a race track it tries to push all of the oil out of it, in a real hurry too! In my last diagnostic testing I removed the catch can setup and have the three breathers from the rocker covers running into a huge open bottle to try and take any breathing restrictions out of the equation. It STILL wants to push oil out after a bit of sustained high rpm high gear runs. Two laps of Sandown saw about 2 litres come out...don't ask where :laugh:

Lets talk oil pressure. From memory the factory manual for an RB30 tells me it should have about 65psi @ 4000 rpm. I always thought about 10 PSI for every 1000rpm plus base pressure of 20ish PSI was about right. This should mean I should have about 30psi @ idle and roughly 85psi @ 6500rpm. What I see is about 85psi @ idle and then it quickly gets to 110psi @ around 3000rpm and then slowly creeps to over 120psi @ 6500rpm........seems way too high!

What else can I do taking in account the above mods already completed? Am I right in thinking a pump change is next? Maybe I have a dud oil pump and the pressure relief valve is not working correctly? Is my next move to change the pump back to standard? Should I take the N1 pump out and mod it for better pressure relief? It looks like I need to take the engine out to do a oil pump swap, is this correct or can it be done with the engine still in?

AHHHHHHHHHHH!!!! ............to say this is frustrating is an understatement. I hope someone can help.

Cheers

Why did you block the front oil feed?

With my N1 pump I saw 100psi by 5000rpm but that's as high as my gauge went.

I would be wondering what restriction is causing the high pressures.. someone knowledgable engine builder needs to come in here and have a read but could blocking the front oil feed increase the pressure abnormally?

my 25/30 is running 2x 1.5mm oil feeds + the vct feed, standard drains with an N1 pump.

oil pressure once warm is using 10w-40 (also does the same with a peak of 6.5kg using 10w-60)

2kg @ idle

4kg @ 2000

6kg @ 3000+ and holds 6kg to 7500

that works out to be ~90psi from 3000-7500. i know when cold my engine does breathe a fair bit (just air no real oil to it) but it gets much better once its all warmed up and with the catch can on for ~3 months of driving (inc some decent thrashing) i got about 200-300ml of oil in there.

heres a interesting catch setup. The car belongs to a tuner here in Tas.

I wont go into all the specs, but its a 25, 8500rpm, nitto pump, 11L sump .85 restrictor in the rear and I think 1.5 in the front enlarged oil returns etc, he does run the rear -12 drain on the rear of the head and said he found it did... not very much. hydraulic lifter still.

anyways just thought I'd put up a pic as I found it pretty interesting (sorry if no one else does!)

Any more info on that R32. Seems well sorted with a pokey engine, MCA suspension etc. Interested to read more

Any more info on that R32. Seems well sorted with a pokey engine, MCA suspension etc. Interested to read more

A well set up car, lots of goodies. Hollinger box etc.

Spends most of its time racing at symmons plains, has done a low 57 so far and expected to go quicker soon.

heres a interesting catch setup. The car belongs to a tuner here in Tas.

I wont go into all the specs, but its a 25, 8500rpm, nitto pump, 11L sump .85 restrictor in the rear and I think 1.5 in the front enlarged oil returns etc, he does run the rear -12 drain on the rear of the head and said he found it did... not very much. hydraulic lifter still.

anyways just thought I'd put up a pic as I found it pretty interesting (sorry if no one else does!)

Is that a drain from the first (horizontal) can, through a filter and back to the sump?? I say drain as opposed to breather as it's on the bottom of the can..

my 25/30 is running 2x 1.5mm oil feeds + the vct feed, standard drains with an N1 pump.

oil pressure once warm is using 10w-40 (also does the same with a peak of 6.5kg using 10w-60)

2kg @ idle

4kg @ 2000

6kg @ 3000+ and holds 6kg to 7500

that works out to be ~90psi from 3000-7500. i know when cold my engine does breathe a fair bit (just air no real oil to it) but it gets much better once its all warmed up and with the catch can on for ~3 months of driving (inc some decent thrashing) i got about 200-300ml of oil in there.

Thanks for the feedback Titan. Looks like your setup with an N1 works great. You would think that with more restriction in my engine (front feed blocked as per SK's matrix) that it would be better at beating the problem........So far the cause is a mystery...a real shit one :P

Thanks for the feedback Titan. Looks like your setup with an N1 works great. You would think that with more restriction in my engine (front feed blocked as per SK's matrix) that it would be better at beating the problem........So far the cause is a mystery...a real shit one :(

ive got a N1 in my 25 and had the same high oil pressure (peak pressure 116psi at 7000 and above 90-105psi 4500-7000) that was with std restrictors pulled the head off and installed 1x1.5mm restictor rear and blocked the middle, vct feed left untouched found no difference in oil pressure hope that helps answer that question

to fix my high oil pressure i bought a peterson external inline oil pressure relief valve and plumb it inline with my remote oil filter and oil cooler lines now i can adjust my pressure as i see fit

004.jpg

005.jpg

  • 2 weeks later...
ive got a N1 in my 25 and had the same high oil pressure (peak pressure 116psi at 7000 and above 90-105psi 4500-7000) that was with std restrictors pulled the head off and installed 1x1.5mm restictor rear and blocked the middle, vct feed left untouched found no difference in oil pressure hope that helps answer that question

to fix my high oil pressure i bought a peterson external inline oil pressure relief valve and plumb it inline with my remote oil filter and oil cooler lines now i can adjust my pressure as i see fit

004.jpg

005.jpg

Hi Kyle, thanks for the feedback. This thing is doing my head in. Awesome fix! Did you have to mod your internal oil pump as well as fitting the external pressure relief valve?

i didnt need to mod the oil pump at all becuase im running a lower relief pressure via the external one, main reason i went this way was becuase it was easyer for me to do the external relief valve set up then to pull the sump off to get the oil pumps relief valve to alter the spring tension and that would of been a trial and error till i got the right pressure

Yeah, after thinking about it, it makes sense that if you want to lower the pressure you don't need to mod the oil pump as you are just adding to the negative if you know what I mean. How does the relief valve "bypass" the pressure? Does it need a return fitting on the sump?

i didnt need to mod the oil pump at all becuase im running a lower relief pressure via the external one, main reason i went this way was becuase it was easyer for me to do the external relief valve set up then to pull the sump off to get the oil pumps relief valve to alter the spring tension and that would of been a trial and error till i got the right pressure

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



  • Similar Content

  • Latest Posts

    • Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...