Bill, 

13-15# is about "normal" for my engine, although occasionally I've seen 20 psi.  As the engine and coolant heat they expand which causes the pressure to rise.  If you get localized boiling around the plugs, you're liable to see higher pressure.  The cap should release at 21#, so that is the max your engine will be subjected to.

Someone asked (I think it was Kelley) about how my Renesis water pump was working out.  Well, I'm happy to report that it seems to be working great.  This is the trick Mazda Trix custom cartridge ($275/ea).  It seems to work as well as the stock 20B cartridge did, but it weighs about 8 lbs. less.  Works out to $100 per 3# of weigh loss.  I hear that is a good cost ratio.  

Mark  

On Sun, Mar 6, 2011 at 10:29 PM, Bill Bradburry <bbradburry@bellsouth.net> wrote:

What is an acceptable water pressure?  As the temp increases my pressure rises to 14 and more PSI.  this seems excessive to me.  What pressures are you folks running.  I have a 21 PSI cap.

 

Bill B