Rb26 Oil Pressure

[hkssam]

guys,

internals replaced with forgies. running N1 pump oil pump. almost done 1000kms. idle set to 1000rev.car running with mechanical oil pressure meter since factory one not accurate.

Cold start it stays around 5bar. then at

• idle (1k) it stays at 1bar.
  
• 2k ==> 2bar
  
• 3k ==> 3bar
  
• 4k ==> 4 bar
  

Ive checked few past SAU topics one said 1bar @ 1k is alrite.

couple of mates said 1bar not enough.

please advise whether it is ok or not. looking for immediate help.

[GTRNUR]

It all depends on many factors which you have left out.

Oil temp

Oil viscosity

Crank and rod clearences

Head type and restrictor

Remote filter.

But to cut a long story short, minimum you want 10psi/1000 rpm. 1kg/cm = 14.5psi, which is fine for idle when your oil temps are at ~90+ degrees

I believe you will see it immediatly jump up to at least 3kg/cm or more at 2000 rpm. This is where it matters, when the engine is actually carrying some load on its bearings.

[hkssam]

It all depends on many factors which you have left out.

Oil temp

Oil viscosity

Crank and rod clearences

Head type and restrictor

Remote filter.

But to cut a long story short, minimum you want 10psi/1000 rpm. 1kg/cm = 14.5psi, which is fine for idle when your oil temps are at ~90+ degrees

I believe you will see it immediatly jump up to at least 3kg/cm or more at 2000 rpm. This is where it matters, when the engine is actually carrying some load on its bearings.

thanks for your input. haven't notice immediate jump. pressure rises gradually as i mention earlier. need to put oil temp gauge

[N1GTR]

You're using the stock oil pressure gauge aren't you?

Try a QUALITY aftermarket one and leave the stock temp gauge for now if you're on a budget. A great option is the defi tri gauge

[GTRNUR]

I believe he meant he was already using an after market gauge, not the factory one.

Bad choice of words on my part using the word 'jump' too.. I meant increase, and gradually like you have seen is normal.

[N1GTR]

Fair enough, my mistake!

[The Dan]

Fairly sure there is some sort of problem there. Oil temp and viscosity won't effect it that much at idle. The only time you ever see them below 20psi is if there is a problem. Even the standard oil pressure warning light comes on before 1bar.

Get an oil test and stop driving it until you get the results back. If it's shagged, you will reduce the costs emmensely if you don't drive it around

[mico]

+1 seems a tad low.

[260tech]

Dumb question perhaps but I haven't found the answer in posts so far, (no doubt it's there somewhere but read my sig., )............

With reference to the well chewed over Nissan RB indicated oil pressure dodgy numbers/incorrect reading issue, is the problem with the sender (transducer on or adjacent engine block) or the receiver, (final indicator/display in cabin) or both? The reason I ask is that I like my cabin array & am not keen on hanging other aftermarket (DEFI) displays in place which may or may not fit in the same slot as originals if I can simply upgrade my primary element. (Transducer in engine bay), out of sight.

Cheers, GW

[The Dan]

Dumb question perhaps but I haven't found the answer in posts so far, (no doubt it's there somewhere but read my sig., )............

With reference to the well chewed over Nissan RB indicated oil pressure dodgy numbers/incorrect reading issue, is the problem with the sender (transducer on or adjacent engine block) or the receiver, (final indicator/display in cabin) or both? The reason I ask is that I like my cabin array & am not keen on hanging other aftermarket (DEFI) displays in place which may or may not fit in the same slot as originals if I can simply upgrade my primary element. (Transducer in engine bay), out of sight.

Cheers, GW

9 times out of 10 it's the sender unit

[rob82]

Fairly sure there is some sort of problem there. Oil temp and viscosity won't effect it that much at idle. The only time you ever see them below 20psi is if there is a problem. Even the standard oil pressure warning light comes on before 1bar.

Get an oil test and stop driving it until you get the results back. If it's shagged, you will reduce the costs emmensely if you don't drive it around

Hmm pretty sure oil temp will have a huge effect on oil pressure. If your talking hot oil then it sounds a tad low at idle but i wouldn't be overly concerned with those readings. Depends a lot on your bearing clearances - maybe a little on the loose side.

You sometimes notice lower oil pressure at idle with aftermarket/higher flow pumps due to gear mesh tolerances being slightly larger making them less efficient at lower speeds.

[GTRNUR]

+1 to what Rob has said.

Granted there are a lot of faulty senders in R32's out there, but he did say "mechanical gauge" so thats not a factor.

At idle with most engines, the oil pressure relief valve isn't even opening. Pressure in the system is entirely determined by flow at the pump, the clearences with the bearings and cams, (ie, the restrictions between the oil galleries and where it returns to the sump), AND the viscosity of the oil.

Because oil viscosity varries with the weight of the oil and the oil temperature, then temperature is also a critical factor.

Really, so long as there is some pressure at idle the bearings are safe, AT IDLE. A low idle will directly influence pressure too, so a 900-950 rpm idle is what to aim for.

What matters is maintaining a pressure rise that is consistent with the RPM increase in order to maintain a lubricating oil film on the bearing and crank surfaces, so there is no abrasive contact. And as I said, 10psi / 1000 rpm is considered a minimum. If you have more than this at 2K,4K,6K and 7500K then you have nothing to worry about.

Just don't go banging the rev limitor with the N1 pump, or expect a failure like Piggaz had...

[The Dan]

Hmm pretty sure oil temp will have a huge effect on oil pressure. If your talking hot oil then it sounds a tad low at idle but i wouldn't be overly concerned with those readings. Depends a lot on your bearing clearances - maybe a little on the loose side.

You sometimes notice lower oil pressure at idle with aftermarket/higher flow pumps due to gear mesh tolerances being slightly larger making them less efficient at lower speeds.

I am fully aware that temperature effects viscosity and therefore pressure but what I am saying is that with the pressure as low as he is reporting, there is something wrong. Hot oil and even sloppy tolerances usually see at least 20psi at idle.

A car that normally runs 25-30psi hot idle (normal) will still only see a drop of about 4-5psi even if the temps go up by 40 degrees. He's looking at a 10-15psi drop from a normal reading

[Hadouken]

What oil are you using? This would affect oil pressure

[KiwiRS4T]

My RB30 with an N1 pump cruises at 100 psi and idles at 43 psi

[mico]

Dumb question perhaps but I haven't found the answer in posts so far, (no doubt it's there somewhere but read my sig., )............

With reference to the well chewed over Nissan RB indicated oil pressure dodgy numbers/incorrect reading issue, is the problem with the sender (transducer on or adjacent engine block) or the receiver, (final indicator/display in cabin) or both? The reason I ask is that I like my cabin array & am not keen on hanging other aftermarket (DEFI) displays in place which may or may not fit in the same slot as originals if I can simply upgrade my primary element. (Transducer in engine bay), out of sight.

Cheers, GW

nah mate u cant mod the standard gear to read more accurately, its a failure. i drilled a bigger hole in the sender and although it did make the dash gauge go up higer, its doughy and slow to react.

[NoFigJamHere]

I am fully aware that temperature effects viscosity and therefore pressure but what I am saying is that with the pressure as low as he is reporting, there is something wrong. Hot oil and even sloppy tolerances usually see at least 20psi at idle. A car that normally runs 25-30psi hot idle (normal) will still only see a drop of about 4-5psi even if the temps go up by 40 degrees. He's looking at a 10-15psi drop from a normal reading

+1 for sure... 1 bar at idle with a mechanical gauge = there is an issue. The oil your using will have an effect on oil pressure both hot and cold. And remember guys he's just had the engine rebuilt! That and the fact he has gone to the trouble to put in a mechanical gauge says to me that he's getting a very different oil pressure reading from before and after rebuild...

[260tech]

9 times out of 10 it's the sender unit

Cheers Daniel. Time to track down a reliable compatible substitute. Any suggestions?

Thanks

GW

[The Dan]

Cheers Daniel. Time to track down a reliable compatible substitute. Any suggestions?

Thanks

GW

If it's not a track car then I would just recommend replacing the standard sender unit. Available from nissan at about $200. You can buy cheaper gauges to do the job but it's certainly not going to last 15-20 years like the standard ones do

[EAT26]

If it's not a track car then I would just recommend replacing the standard sender unit. Available from nissan at about $200. You can buy cheaper gauges to do the job but it's certainly not going to last 15-20 years like the standard ones do

+1

My GTR had a issue where it would on occasion drop oil pressure 10-15psi and it was the sender, got the sender myself through nissan got Dan ^^^ to fit it and haven't had any more issues until my engine ate a piston.