oil pressure in rebuilt 78 930 turbo

[fredmeister]

I have a question on what oil pressure should be expected to see on a rebuilt 78 930 turbo engine.
I drove a 78 turbo that I was considering buying with a freshly rebuilt 3.3 liter engine. The oil pressure on the gage read about 1 bar at idle but only peaked at barely 3.0 bar even under boost and 4500-5000rpm. This bothered me as I expected to see roughly 1 bar for every 1000rpm.
The seller says that he thinks the gage is off calibration because the oil temperature reads high and the pressure low when I pointed out my concern. He said that his experience was that all cars read differently, some high some low......my 911SC reads 3.5-4.0 bar at anything above 4500rpm.
The engine was freshly rebuilt less than 800 miles ago with new bearings and pistons/cylinders, cams, the works.
Is this possible or anyone have an opinion to give before I pursue buying this car?

[magic930]

When cold I get 4.5 bar at 4000 rpm
When warm I get 3.5 bar at 4000rpm
At idle cold its 2.0 bar
At idle warm its 1 bar
this is with 15w-50 synthetic Mobil 1

It could be he is running a lighter weight oil?... also a new pressure sender is about $80 so you could ask him to put a new one in and see if its any different.

[johnsjmc]

I have similar press in a 3.6 conversion.It peaks at about 3 hot but maintains 1+ at hot idle. Low idle press usually indicates worn main brgs. I am at a loss to explain low peak press except bad guage/sender or a weak pressure relief spring.I use 1/3 15/40 syn and 2/3 20w50 dino and have 2 carrera coolers.

[Eagledriver]

These guages are often not accurate. You might try a replacement sensor to see if you get a different reading.

-Andy

[78P930]

My readings on my 78 are the same as David's(magic930).

[cstreit]

I'd check it with a mechanical gauge.

What oil are you using?