I'm posting this for a friend of mine. He has an S13 Det swap...

well the fsm says 11psi at idle... and 46-57 @ 3200 rpm...

at idle it does sit at about 11psi.. and "gettin on it" it creeps to 75 and cruising it vary's between the 20-50psi...

so i'm sittin thinkin... ok my oil pressure is fine... and i'm an idiot for thinkin my car needed an oil pump because it had pressure...

here is the problem...

absolutely no oil pressure when i start it up... and takes a second to build pressure... there is obviously no oil in the head.. because it makes a nasty sound.... now if i turn the motor over for a second before start it (starter hooked directly to button and then battery) it will build enough oil pressure where the motor doesn't make a noise when its started...

anyone know what it might be? in most motors there is a one way valve that does not alow all the oil to drain out of the head when its not running.. i looked at the engine lubrication diagram and don't see a similar type valve in the motor... *oil pressure releif valve thats in the oil filter is not what i'm talkin about*

since i've been having this problem i tried changing the oil/filter

Redtop S13 motor...

I don't think there's a problem. that's why like 95% of engine wear is during startup; no oil pressure.