Hi everybody
First excuse me if my English is not perfect, I'm French and do my best to be understand
Question about an oil pressure. I have a swap ls1 in a Nissan 240sx.
The ls1 is 383 stroked with trick flow genx220 heads, camshaft, fast intake, 102mm throttle, melling high volume oil pump...

At the first starts , the oil pressure was at 4 bars at idle (sorry In France we don't talk in PSI) and the pressure goes up to 5 or 6bar throttle open.

But in race track, the oil pressure was suddenly down under 1.5bar. So i shut down the engine cause I though something going wrong.

So I've check the engine to see if there is anoil leek or something else. No leeks, no blue smoke at exhaust and the 8cylinders are running perfectly.
But Now, after that, I've just 2 or 2,5bar at idle.

Question :
what can be the reason of an oil fail ?
These pressure are good for an LS engine ?
What type of oil do you use for race utilization ?

Thank you in advance

 

Possibly bearings? How many miles on melling pump?
What oil are you using?

 

Have you changed the oil to see what it looked like and cut the filter open? When you installed the oil pump maybe you possibly had a small kink in the o ring? I would think that it would have been that way from the start if that were the case, but you never know. I'd start with seeing how the oil looks and go from there.

 

I've make a rebuild so the pump is brand new.
In case of a dead bearing, it seems to make noise, no ?
The oil is 10w40. The engine is in honing.
I've only open the front cover to check the oil pump and the retaining plate. All seems to be okay.
I have to take the engine out of the car to check the bearing and the pickup tube ...

 

Drain the oil and look for shiny metal. Remove the oil filter and cut it apart to look inside. If there is metal in there you have a bearing issue. A bearing issue can cause a loss of pressure at idle.

 

I think I've found the issu.
After drain oil, I've found some shinny metal.
So I've drop out the engine, open the oil pan and found that all bearings were dead...
But why ?
The barbell was not in his place so it makes a oil leeks inside the engine that's why I lost the pressure I think.
Now the crankshaft is in repair and need new set of bearing. I've bought a new barbell to replace the defect one.
Hope it's gonna be better now.
Thank you y'all for your answer.