I have researched this topic in the World, Club, Rennlist, Pelican and Google.

Is there any justification for this - in writing from a trusted authority?

Thanks,

What motor we talking about ? t4 won't make 10psi/1000rpm but a "6" will make that easy.

It is a type 4. About 10psi/thousand is the only number I have ever seen - rarely - but still the only number. I'm running about 8 and wondered have how much "about" means.

If 10 is on the high side, good for me. But is there anything to support any number?

Thanks to all.

A fresh or good mechanical condition T4 will make 10psi/1000 rpm hot easy.
Thing is there's many factors at play so the 10psi/1000 rpm isn't a hard rule, just a good ballpark. Plus the figure may drop slightly as you get over 4K rpm. Also many aftermarket gauges like VDO aren't totally accurate.

As they get older it may flicker the idiot light at slow idle. I've seen old engines, with obviously a fair bit of wear, only making say 7-8psi/1000rpm (hot) and ticking along just fine.
Any less than that and you know that it's almost rebuild time or it has an oil control issue.

Bruce Anderson and Alan Caldwell have both cited the 10 PSI/1000 RPM figure in Panorama over the years. It is always mentioned as a rule of thumb, not a spec.

--DD

The type 4 2270 that I used to own, and was built by McMark, made about 15psi/1000rpm.
But 10psi/1000rpm is the general number I've always seen for stock VW air-cooled engines, both type 1 and type 4 when they're in good shape.
It's an approx number, not a spec. As they get on with higher mileage the number goes down.