# whats the minimum oil pressure needed?



## mattysupra (Oct 31, 2008)

what is the minimum oil pressure you can have before issues? 

for instance the thinner the oil you use the lower the pressure you have? 

Or 

you have a accusump and this may be refilling stealing some of your oil supply? 

Or

You have increased the size of the oil ways Etc Etc!! 

Would you need maybe 1 bar + of oil pressure to keep the engine safe at maybe 5000rpm or would you need alot more pressure than this?


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## freakazoid3 (Jan 19, 2008)

The thinner the oil and the bigger the clearance the lower the oilpressure.

I do see when starting up my GTR that when the accusump is used before the actual startup (to prime the system) it takes longer to get the full pressure after starting and when at idle as the accusump is filling up again and stealing maybe 2 bars or the max idle pressure when cold until she's all full again.

Don't know if that's what your wanting to know though 

And the needed oilpressure depends on engineload big time 
@5000 rpm I'dd like to see at least 4bars on a hot engine


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## mattysupra (Oct 31, 2008)

why do you need more oil pressure when the engine is running high rpm? 



Also your accusump, what PSI do you have it set at on the gauge? For instance if you emptied the accusump with engine off then what does the PSI on the gauge say? 

Im not sure if mine is dumping the oil to soon!


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## R.I.P.S NZ (May 7, 2004)

mattysupra said:


> why do you need more oil pressure when the engine is running high rpm?


More load trying to squeeze the oil out away from the bearings. 



mattysupra said:


> Also your accusump, what PSI do you have it set at on the gauge? For instance if you emptied the accusump with engine off then what does the PSI on the gauge say?


I preload them 15psi when empty, then when primed I open them and start cranking (starting the motor) within 2-3 seconds at most so when the motor fires not alot of oil is needed to top it back up.

If you empty the accusump with the motor off, your best to start the motor with the accusump closed then once running, with the rpm up around 3000-4000, slowly open the accusump while keeping an eye on the oil pressure guage, if you do it right you'll only see around a 10psi drop in oil pressure for a few seconds.

Rob


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## freakazoid3 (Jan 19, 2008)

As Rob says I have mine pre-loaded to 1bar too


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## mattysupra (Oct 31, 2008)

Is 1 bar enough tho? 

Would that not mean that your oil pressure would have to drop below 1 bar for it activate. As it is only likley to activate at high rpm? do you not run the risk of say having 1 bar oil pressure at maybe 6000 or so rpm? 

If you set the pressure higher i guess it will always be emptying itself at low revs tho? 

What is the minimum oil pressure you should have with hot oil at tick over? Guess it needs to be set just above this. Or is that 15 psi?


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## mifn21 (Mar 19, 2007)

Healthy engine should be at least 1.8 bar at idle with a stock pump


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## mattysupra (Oct 31, 2008)

mifn21 said:


> Healthy engine should be at least 1.8 bar at idle with a stock pump


with hot oil? 

any idea what the minimum oil pressure on a N1 pump is?


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## R.I.P.S NZ (May 7, 2004)

mattysupra said:


> Is 1 bar enough tho?
> 
> Would that not mean that your oil pressure would have to drop below 1 bar for it activate. As it is only likley to activate at high rpm? do you not run the risk of say having 1 bar oil pressure at maybe 6000 or so rpm?
> 
> ...


Your mistaken on how the unit works, the 1 bar pre-load has nothing to do with oil pressure, thats the AIR pressure you put on the opersite side of the piston in the accusump, its so when you have 0 oil pressure, the 1 bar of air pressure will empty the accusump.

Have a read up on how they work, they are great bits of kit if they are setup and used right, I regularly exceed 3g with a normal wet sump and tomei oil pump and have no oil pressure/bearing issues.

Rob


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## Staffie (Mar 16, 2006)

mattysupra said:


> with hot oil?
> 
> Yes, that's what he means.
> 
> ...


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## _dan_ (Jan 24, 2010)

Mine has N1 pump (apparently) and hits 7.5 when started cold, drops to 2.5 when idle and hot.


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## Undutched (Sep 29, 2006)

I didint want to start a whole new thread.

Im running a 5w50 (Mobil 1)

Cruising ,start up, etc. its fine. 

But when I park it after a little city driving the oil pressure is 1 bar or less ( the light does not turn on though)

What could cause this?


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## scoooby slayer (Jun 13, 2009)

Undutched said:


> I didint want to start a whole new thread.
> 
> Im running a 5w50 (Mobil 1)
> 
> ...


a 15w will help pressure.


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## Undutched (Sep 29, 2006)

I have a 15w50 (Motul 300V) here, but just filled in the 5w50 oil maybe 600-700 miles ago.

Should I switch right away or is it okay?


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## Marky_GTSt (Dec 31, 2005)

Undutched said:


> I didint want to start a whole new thread.
> 
> Im running a 5w50 (Mobil 1)
> 
> ...


Pressure is cause by a restriction to flow, the items that restrict flow are your internal engine bearings, So if the pressure is low either the oil is too thin the bearings are worn or the pump is worn and not generating enough flow. My Main bearings where quite badly worn but I was still getting 2 bar+ when warm.

Its also possible that the gauge is giving you a false reading.


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## Multics (Apr 27, 2008)

So what's better, flow or pressure? 
Pressure will vary depending on oil weight, temp and restriction (clearances).

I guess there's a fine balance between flow and pressure.

All the numbers quoted by Nissan in their engine repair and owners manual are based on the assumption that you use their recommended oil grade which I think is 7.5w30 for the RB engines.


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## Nigel-Power (Dec 16, 2009)

Undutched said:


> I didint want to start a whole new thread.
> 
> Im running a 5w50 (Mobil 1)
> 
> ...


Mobil one is too thin, I wouldnt recommend using it in a moded GTR


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## dan-hipgrave (Nov 22, 2008)

Nigel-Power said:


> Mobil one is too thin, I wouldnt recommend using it in a moded GTR


I agree - used it once and changed it very quickly afterward. Fuchs Titan all the way.


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## freakazoid3 (Jan 19, 2008)

If your reading it off the OEM gauge then don't trust it and get a real gauge on there before doing anything else


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## MS33 (Jun 27, 2007)

Nigel-Power said:


> Mobil one is too thin, I wouldnt recommend using it in a moded GTR



When you say to thin, are you referring to the 5W/50 Mobil 1?

I've used 15W/50 Mobil 1 for the past 2 yrs and haven't had any problems at all.


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## Nigel-Power (Dec 16, 2009)

MS33 said:


> When you say to thin, are you referring to the 5W/50 Mobil 1?
> 
> I've used 15W/50 Mobil 1 for the past 2 yrs and haven't had any problems at all.


Wouldnt recommend any grade of mobil 1, motul or silkolene


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## MS33 (Jun 27, 2007)

Nigel-Power said:


> Wouldnt recommend any grade of mobil 1, motul or silkolene


Why not? What are your reasons for not using Mobil 1?


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## Undutched (Sep 29, 2006)

I have Motul 300V 15w50. Ill throw that in then, but can I keep the oil filter, or should I change it as well. I mean 600 miles ?!?!


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## Jags (May 20, 2007)

Motul and silkolene oils are fine, they're fully synthetic ester based and are spot on for high performance cars like GTR's- just make sure you use a suitable grade.


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## nozza1 (Jan 13, 2007)

Nigel-Power said:


> Wouldnt recommend any grade of mobil 1, motul or silkolene


Agree on the mobil 1, but why the other two.

Rb motorsport recommend Silkolene and MGT Racing recommend Motul.

Whats your reasons?


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## Nigel-Power (Dec 16, 2009)

MS33 said:


> Why not? What are your reasons for not using Mobil 1?


Horror stories mate, two 300ZX 500+ horses, blown engines, due to oil not circulating properly (ie oil starvation) although the right grades of mobil 1 were chosen by a Z32 tunning garage, with plenty of Z32 expertise "supposedly". In fact one of their own engines had a similar faith due to mobil 1 seeping out from rocker cover gasket and even the drain and round the oil filter. Mate's 600hp Supra died too due to oil pump failure. fixed it all up and used the same oil, within weeks blew it again. rebuilt it again and he was advised not to use mobil 1 ever again. since then, now 4 years running his Supra hasn't had no single problem. 
I'm not sure what exactly it is, maybe the viscosity of the mobil oil which tends to give up under high heat or pressure. But I have been advised many times by reputable garages not to use it. Though technically or chemically I wouldn't be able to explain what the cause could be. Some expert may add to this or correct me if I'm wrong. but personally I will stay away. 
btw, what sort of power are you running in your 33? how tuned is it internally?


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## Nigel-Power (Dec 16, 2009)

nozza1 said:


> Agree on the mobil 1, but why the other two.
> 
> Rb motorsport recommend Silkolene and MGT Racing recommend Motul.
> 
> Whats your reasons?


Abbey use Motul, TR use Silkolene, these two brands of oil are specifically for high performance engines, and race bred. In many race championships such as the touring car championships, they use Motul or Silkolene, Some Castrol GTX magnatec, don't know how good the later is though, never used it.


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## scoooby slayer (Jun 13, 2009)

valvoline vr1 fully synthetic is used in nascar.


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## Nigel-Power (Dec 16, 2009)

scoooby slayer said:


> valvoline vr1 fully synthetic is used in nascar.


That's correct slayer. Aren't the nascars tuned excessively though? thought they were 1000+ horses, not sure.. but yeah I have heard of a lot of race usage of valvoline too. 
What do you use in your SPL powered beast?


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## scoooby slayer (Jun 13, 2009)

Nigel-Power said:


> That's correct slayer. Aren't the nascars tuned excessively though? thought they were 1000+ horses, not sure.. but yeah I have heard of a lot of race usage of valvoline too.
> What do you use in your SPL powered beast?


its on mineral 10w-40 at the minute as its fresh built but its done almost 1000 miles so ive just ordered 10 litres of 5w-50 vr1 race oil fully synthetic for £75 i want a 5w as its a street car so need good cold start properties but also need good hot weight hence the 50 for nearly 900 horses at full chat 
silkolene pro-r is rated at 18.2 cst at 100c, vr1 is rated at 18 cst at 100c so very close and has better cold start properties, thats my reasoning behind choosing that oil. silkolene pro r is the best but to thick for cold weather start ups


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## Nigel-Power (Dec 16, 2009)

scoooby slayer said:


> its on mineral 10w-40 at the minute as its fresh built but its done almost 1000 miles so ive just ordered 10 litres of 5w-50 vr1 race oil fully synthetic for £75 i want a 5w as its a street car so need good cold start properties but also need good hot weight for nearly 900 horses at full chat


10 litres? presumably it doesnt take that much oil does it? even with an extended oil sump. or is it because you can only buy the oil in 5 litre containers and you need a liter or 2 more than 5.


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## scoooby slayer (Jun 13, 2009)

Nigel-Power said:


> 10 litres? presumably it doesnt take that much oil does it? even with an extended oil sump. or is it because you can only buy the oil in 5 litre containers and you need a liter or 2 more than 5.



holds about 6.5 i think, just toping up oil


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