my wild guess is up to 1,000 psi........and that's a very wild guess.
why do you ask ?
On page 47.9 of the Bentley manual, for checking the brake pressure
regulator.......( which I'd call more of a pressure limiting valve for the
rear brakes )
they say  ( after attaching pressure gauges front and rear ) .........
'increase front brake pressure to 1,450 lbs.  The pressure gauge on the rear
brake should read 793 to 943 psi."

I was in the ball park more or less.
why, hoses bursting ?
fwiw, in working to get an SVX Syncro  Vanagon with SA front brakes and rear
discs, to work really well in the brake department, I worked with a racing
brake company on it  for a while. They told me 'really high pressures are
not a good thing, hydraulically speaking."   Perhaps 2,000 psi would be  a
practical limit is what I kind of gathered.
Scott
www.turbovans.com

----- Original Message -----
From: "Mike Collum" <collum@VERIZON.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, October 10, 2008 6:27 PM
Subject: Brake hydraulic pressure

> Does anyone have a feel for how much hydraulic pressure is in a
> Vanagon's brake lines during hard braking?
>
> Mike