oil presure

[hoopfol]

on cold stard my oil presure is hi +- 7 bar and as the engin is geting hot it drops to 2 bar is it normal ?

[carsonmx114]

I think you're fine. Colder oil is thicker so the pressure is higher. Hot oil is thinner so the pressure is lower.

[Lawrence Coppari]

Mine pegs at 5 bars at idle when cold. It stays at 3.5 bars at idle when hot. Oil is Mobil 1, 15-W50. Engine has 180K miles on it.

[HondaDustR]

Yeah, that's about right. I'm running 0W-30 for the cold weather and it pegs at startup, but gets there ALOT quicker on sartup in cold temps that the Brad Penn 20W-50 that was in there. It holds a solid 2 bar at idle once warmed. I like the 30 weight for the winter, but may keep it for the summer depending on how it does. Hydrodynamic bearings don't need pressure to work, they need flow to stay cool. As long as there's enough pressure to ensure good supply to all the bearings (~10 psi per 1000 rpm), thinner is better since it will flow more and cool the bearings better at higher rpm. Formula 1 motors run 10 and 20 weights and they'd have to to make the bearings last at 18K rpm. 25 year old production motors don't have the bearing clearances needed to be able to hold enough pressure for oil that thin, but the principle is the same. That 50 weight opens the OPRV at 2500rpm and after that, that's all the flow the bearings get. The rest goes out the OPRV into the sump, since 50 weight can only flow so fast through very small bearing clearances at 4.5 bar. The more easily the oil flows, the better, as long as it doesn't go too thin and drop pressure.

[wild man]

Seven bar seems kinda high. Isn't the OPR valve supposed to open at somewhere around 5bar? If I crank my 951 in cold weather (using heaving oil) with the coil disconnected, it first spikes up to 5bar. Then it settles back to just over 4 and remains there. After being started, it stays between 4 and 5 bar, no matter what the rpm.

[ernie9944]

My 968 oil pressure on initial start up with 20w50 & after a hard run idling at 1100 rpm if idle come down to 950 after a hard run oil pressure will settle at 2- 3/4 bar agree with__wild man__ 7 bar will be a little higth.

[ernie9944]

Originally Posted by hoopfol

on cold stard my oil presure is hi +- 7 bar and as the engin is geting hot it drops to 2 bar is it normal ?

Correct me if I'm wrong but I don't think any 944-951-968 has pressure gages witch are grade to 7 bar. Usually there are from 0 to 5 bars.

[HondaDustR]

Originally Posted by ernie9944

Correct me if I'm wrong but I don't think any 944-951-968 has pressure gages witch are grade to 7 bar. Usually there are from 0 to 5 bars.

I thought so, too, but came across this in a 83 944 manual pdf that shows the old 924 10 bar gage. Personally, I'd rather have the 10 bar gage.



Given how the 5 bar gage pegs on cold startup, it has to be at least more than 5 bar on startup. The OPRV opens at 4 bar, but when the oil is cold it still can't flow enough wide open to regulate the pressure with thick oil. 7 bar sounds about right for winter starting, and is definitely too high for operating temp.

[hoopfol]

yes it is a 1982 924 . same as pick . i did chance the motor 2.2 5 cylinder but it hafe all the origenal presur sender units . i'm from south africa and porcsh parts are pricy hear . the conversion same cost than 2 neu pistins for the old motor.
and it is runing mutch beter with the 5 cyl motor

[carsonmx114]

I'd like to see pics of your car... and your engine swap.

[hoopfol]

hi hear is some pics . it stil need som tidy up work .

[Rasta Monsta]

Originally Posted by HondaDustR

Personally, I'd rather have the 10 bar gauge.

Yeah, that is JUST what you need, man. . .one more thing to fret about.