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Oil Pressure Drop On Boost.

EAT26

By EAT26,
in Engines & Forced Induction

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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?

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https://www.sau.com.au/forums/topic/378802-oil-pressure-drop-on-boost/
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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.

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