Ok, so I realise i can't do a 3 year engineering degree in 30 minutes
I looked at this
https://engineerexcel.com/venturi-meter-and-orifice-meter-difference/ and considering your note above it seems I should look at putting some sort of taper on the underside of the aluminium component to reduce turbulence & effect on flow
With walls of 1.5mm I was also thinking of thinning those out, but then decided I didn't really have the right equipment
On other engines, I am used to there being an excess of capacity, such that the relief valve operates when the engine is cold and revs are moderate. As the oil heats up and becomes less viscous, the relief valve drops out of the equation and low pressure on hot idle is your early warning sign
Indeed, I did an engine once after a long drive at high engine speeds. Somebody pulled out which resulted in a need to drop speed, as soon as the revs came off one of the big ends started to knock & run the bearing. I had to pull over, let it cool down and then drove very modestly to get home
I too hope that the original design does have a bit of a safety factor. Todays engineers are often focussed on value engineering though. Interesting comment on the pickup though
I think I'll go for it, and see how it goes. After all, removing the sump isn't such a difficult or expensive job