Jump to content
SAU Community

Oil Pressure Drop On Boost.

EAT26

By EAT26,
in Engines & Forced Induction

 Share

Recommended Posts

EAT26 Community Regular

EAT26

Posted
Posted

Hey everyone,

Got an issue with the GTR, curious if anyone else has had the same...

On low boost I was loosing oil pressure..... it would drop from 5-4 bar when giving it hard on gate pressure.... now I took to a shop and I got a Mechanical gauge on it..... we topped up the oil as it was low.. and now it only looses pressure on high boost where it drops about 20 psi... I am hoping this is not a engine out job, but assuming pump, or engine damage the engine runs fine as it is... So I dunno seeing as its only on boost I am hoping its just a turbo issue....

It is fine Free revving, No engine noise, oil pressure is fine, no smoke... the night before I had 2 intercooler pipe blow offs when I was on the 2 step at willowbank.... assuming this caused it.

There was a fair bit of oil in the cooler pipe not sure if turbo is ok, checking it tomorrow.

Has anyone had it where the oil pressure has dropped on boost?

Link to comment
https://www.sau.com.au/forums/topic/378802-oil-pressure-drop-on-boost/
Share on other sites
  • Replies 69
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

GTRsean Grand Master

GTRsean

Posted
Posted

You got an aftermarket sump baffle, not the stocker...

My old car would drop off when accelerating in the first 3 gears. Only had a stock sump baffle.

My aftermarket oil pressure gauge showed the drop, and that was with 5l of oil in the sump.

After that I always put 6litres in every oil change in GTR's and that seems to stop the problem, before it's too late.

GTRsean Grand Master

GTRsean

Posted
Posted

When I had the 26 apart, I measured how much oil you could put in the sump without it getting whipped up by the crank.

6litres fills the sump to the brim. When the engine is running a certain amount is in circulation (in the oil galleries, oil pickup, head, turbo's etc) and it ran with no dramas. I had done that for years, and also do it to my 34. Never killed an engine, just gearboxes!

The oil I use comes in a 6 litre container so no problems for me :)

Another point, the stock oil pressure gauge is not quick enough to tell you that you are losing oil pressure for those few brief seconds, when it does it's definately too late! spin a bearing anyone??

GTR_JOEY Grand Master

GTR_JOEY

Posted
Posted (edited)

Cool stuff.... cheers for the info

Just found a massive thread on the forum where the general concensous is to over fill by a litre which would take it to just under 6L...

what oil do u buy that comes in 6L btw?

How much power do ur 26 have and how often did u give it some stick?

Edited by GTR_JOEY
GTRsean Grand Master

GTRsean

Posted
Posted

No worries!!. I just run nulon 10W40 and change it every 5000km or less. Also run a relocation kit and oil cooler.

See my sig for the 32.

34 is currently on 294 all wheel kw, with more soon...

It's mostly cruising, with the odd twisties thrown in with 7000RPM plus sometimes.

Big thing is servicing and keeping the little things in check with these cars.

linkems Collaborator

linkems

Posted
Posted

No worries!!. I just run nulon 10W40 and change it every 5000km or less. Also run a relocation kit and oil cooler.

See my sig for the 32.

34 is currently on 294 all wheel kw, with more soon...

It's mostly cruising, with the odd twisties thrown in with 7000RPM plus sometimes.

Big thing is servicing and keeping the little things in check with these cars.

Do you drop the oil in the oil cooler as well, when you do your oil changes?

EAT26 Community Regular

EAT26

Posted
  • Author
Posted

Yes I have....although I think it was load, not boost. I spun a big end bearing shortly after. seriously.

I dont like that idea :( lol.

You got an aftermarket sump baffle, not the stocker...

My old car would drop off when accelerating in the first 3 gears. Only had a stock sump baffle.

My aftermarket oil pressure gauge showed the drop, and that was with 5l of oil in the sump.

After that I always put 6litres in every oil change in GTR's and that seems to stop the problem, before it's too late.

Stock baffle. I am going to try the overfill idea, hopefully that solves the problem but yeah... do you know what causes it?

Don Dada Mentor

Don Dada

Posted
Posted

You got an aftermarket sump baffle, not the stocker...

My old car would drop off when accelerating in the first 3 gears. Only had a stock sump baffle.

My aftermarket oil pressure gauge showed the drop, and that was with 5l of oil in the sump.

After that I always put 6litres in every oil change in GTR's and that seems to stop the problem, before it's too late.

My Rb26 is rwd and it surges like a bitch if you fill it to the normal H mark on the dip stick, so I for you guys with a little more grip of the awd, it would obviously be worse.

When I fill it with 5.5L it sits just above the H itself on the stick, but it still surges a bit, but I think it should be ok for normal street duties....Track will definately use 6L.

EAT26...Does it drop only on hard accel.? Or does it do it too when already in motion and bringing up the revs?

EAT26 Community Regular

EAT26

Posted
  • Author
Posted

Ccome sunday we will sort it out my mang

:thanks::3some::wub:

My Rb26 is rwd and it surges like a bitch if you fill it to the normal H mark on the dip stick, so I for you guys with a little more grip of the awd, it would obviously be worse.

When I fill it with 5.5L it sits just above the H itself on the stick, but it still surges a bit, but I think it should be ok for normal street duties....Track will definately use 6L.

EAT26...Does it drop only on hard accel.? Or does it do it too when already in motion and bringing up the revs?

Its dropped only when Highboost at 21psi is introduced and drops 1 bar on the internal gauge.

Your not flooding the head are you? This would lower the sump level and could cause issues with surge? More oil may not help if its all being pumped up.

Just a thought?

Honestly do not know lol.

GTRsean Grand Master

GTRsean

Posted
Posted

You seem to be pulling lots of G's!!! in acceleration.

About the only way to fix would be:

In order of cost:

Turn the boost down :no:

Trapdoor sump baffle, eg tomei,(stops some of the oil from going to the back of the sump, away from the oil pickup), stock baffle is not that effective, except for stock vehicle...

sump extension with sump baffle (deeper sump to keep oil pickup sucking oil, not air and also holds more oil)

dry sump set up, now we are talking $$$$ (race car stuff, running semi's, slicks, high HP, G's).

Feel free to add any other ideas.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Erelyes
      Ceramic turbine damage to engine - what did yours do?

      By Erelyes · Posted

      Ha, well, it's been.... a bit of a journey. Things have taken much longer than I'd hoped. I'll probably put up a thread at some stage. Hopefully soon. The car's not done any kms since my update in June though, put it that way.
    • Dose Pipe Sutututu
      M35 Aftermarket Fuel Pump

      By Dose Pipe Sutututu · Posted

      Here's the chart for fuel pressure vs. current draw, assuming your base fuel pressure is 3 bar and you run like 0.5bar boost on WOT, you should only momentarily hit 9amps here and there. (Ignore my prev post, I cannot read a chart these days it seems)
    • GTSBoy
      RB25 Drama's

      By GTSBoy · Posted

      Those comp test results are not hideous. Whether they are accurate or not (ie, when that comp tester says 140 psi, is the real pressure120, 140 or 160?) is unknown to us. The state of the battery used to crank it over is unknown, etc etc. Many people around here would say that the absolute values and the spread are perfectly fine to just add boost and keep going. I personally would be happier with a narrower spread than that, but even the diff between 125 and 145 is not terrible. That one cylinder at 125 though, has probably copped some damage relative to the others. You should inspect the valves seeing as you've got it open. Do you know how to measure installed ring gaps? That, and an inspection of the rings themselves, is how you will determine whether they need to be replaced. If you're not good to do these things, take the block and the pistons and rings to a shop that is, and ask them for the go/no-go on them. Do the bores need a hone at all? If so, you might well be justified in getting some different pistons in order to get away from the ring supply problem. Whether you're happy to spend a lot more money right now, on more gear, rather than less money, but an amount that looks stupid given that you will only get a handful of rings in exchange for that money, is for you to decide.
    • iain_ST44GA
      M35 Aftermarket Fuel Pump

      By iain_ST44GA · Posted

      also possibly backed up to my filler and shat down it! 🤣
    • Julsmadrid
      RB25 Drama's

      By Julsmadrid · Posted

      Ok so i would love some advice here please, i purchased an R33 a few months back and its had a few mods done to the engine, its an RB25det running a Master ECU, 1200cc injectors, bigger turbo, oil cooler, oil filter relocation kit, Spool H-beam rods, acl/ross pistons. When i removed the motor from the vehicle (as its getting a respray) i thought i would compression test it and these are the following results. Cylinder 1-145psi, Cylinder 2-143psi, Cylinder 3-125psi, Cylinder 4-145psi, Cylinder 5-140psi, Cylinder 6-135psi this test was done with the motor on the ground and powering up the starter motor. I dropped the sump and found broken oil squirters on cylinder 3,5 and 6. I was told my rings are probably worn so i stripped the motor completely to get a new set of rings for it. The trouble is no one has these rings anywhere and they have to be custom made by Ross over in the states and will cost about $600+$200 delivery. My question is how can i tell if my rings are at fault and if they are still ok and is this price ok for a set of rings?
×
×
  • Create New...