Scary oil pressure drop in VTEC

[goldNSX]

https://www.youtube.com/watch?v=OS9IAs8Cxek

NOT my car Have a look at the oil pressure gauge when the engine is in VTEC. There is something completely wrong I guess.

 

[stuntman]

Stock gauge is useless. But yes, there is a drop in oil pressure that feeds the bearings when VTEC is engaged, since it needs oil pressure to engage the higher profile cam.

...which is why a baffled oil pan is VERY important for a track car.

 

[goldNSX]

I agree the oil pressure is not acurate but a drop from 4 to 0 is abnormal. I know of a car where the LMA where installed wrong. A pin was lost during installation. That's my guess.

 

[ftuhy]

1. Is the oil fill proper? (What's it read on the dip stick?)
2. Its probably not stock, because it went above 8,000 rpm. On mine, the cutout comes in just a hair above 8,000. So, if my WAG is correct, what is not stock on this engine?
3. On mine, the pressure drops from 4 to 3 when V-TEC cuts in and stays there. I suppose the oil pressure sensor could be bad.

 

[goldNSX]

Related to how fast is goes to 8000 rpm in 1st and the whine I guess it's supercharged.
I also have a drop of 0.5-1 going in VTEC but my gauge is reading generally higher at 6 or 7.

 

[OLDMNSX]

Take a look at this YouTube at the 2:26 point and you will see the same thing.
Brad
https://www.youtube.com/watch?v=Y7Ob7EkPJEQ

 

[ftuhy]

Brad (aka "Eagle Eye"),

Good observation! So, why does oil pressure drop to virtually zero with these particular SC engines, but not with at least most stock engines? I remember, but can't find, a thread from a while back discussing the pressure drop by about 1 mark on the gauge when VTEC cuts in, but never a drop to zero. I'll have to ask some owners with SCs if they see the drop to zero.

A possibility is these are engines with stock bearing clearances and they are using 1xW50 or xW60 oil. That's a no-no for the NSX engine with stock innards. See http://www.nsxprime.com/forum/showthread.php/180489-VTEC-problem?highlight=oil+pressure+V-TEC for an explanation.

That's my WAG on this for today.

Frank

 

[OLDMNSX]

Look at the diagram of the oil system in the NSX engine. The location of the Oil Pressure GUAGE sending unit is located at the END of the oil distribution flow. When the engine is in VTEC mode there isn't much pressure remaining in the system. NOW, if the engineers would have taken the oil pressure GUAGE reading where the Oil Pressure Switch for the Oil Presure LIGHT is taken, located at the oil filter housing, we probably wouldn't even know that this phenomena occurs.
Brad