[Tigers] Tigers Digest, Vol 4, Issue 11

[Jerry & Maureen (Mo)]

Dave,List

The normal pickup point for the oil gauge is after the filter (the point
just above the filter). So what you are reading on the gauge is actual
pressure going to the engine, but what is unknown is the volume of oil going
to the engine.  Now if one has good bearings and the engine is tight one can
assume that there is enough volume of oil going to all of the parts because
the pressure is high. However if you have loose (racing) tolerances the pump
might not be able to supply enough volume of oil to get the pressure you
want.  The same thing might happen with a "restriction" in the oil lines
prior to, or after, in the case of a remote filter.

All oil pumps that I know of have a bypass relief valve.  Nothing more than
a ball held in place by a spring of enough pressure to relieve pressure at a
predetermined pressure.  I know of no way of determining just what that
pressure is, however when you first start a cold engine it's a safe bet that
the highest pressure you are seeing is the pop off pressure. These are
positive displacement pumps so the oil has to go someplace.

When I buy a new oil pump I'm more interested in a higher volume pump than a
higher pressure pump.  If I had a "racing" engine the higher pressure would
be a better bet.

To get a higher pressure you need to change the relief spring, to get higher
volume you need a "taller" pump, one where the Gerotor is thicker (that also
gives higher pressure).

Jerry Christopherson
9473187

     

-----Original Message-----
From: tigers-bounces at autox.team.net [mailto:tigers-bounces at autox.team.net]
On Behalf Of Dave Munroe
Sent: Monday, January 11, 2010 9:58 AM
To: Smit, Theo; tigers at autox.team.net
Subject: Re: [Tigers] Tigers Digest, Vol 4, Issue 11

Theo;

This is a concept I have not considered: are you saying that smaller 
internal diameter oil filter lines will cause a drop in oil pressure to the 
filter? or to the engine oiling system which could be seen on the oil 
pressure gauge?

I have a set of "industrial" oil line hoses on my filter set-up, and am not 
happy with my oil pressure as seen on my dash mounted gauge. I haven't 
checked the internal dia. of the hoses so I don't know if they are indeed 
smaller than they need to be, but it would be interesting if they are a 
factor in my overall oil pressure.

Thanks for this bit of info.

Dave




  If you do get oil lines made at a hydraulic shop, make sure they
 understand that this is for a continuous-flow oiling system, not for a
 hydraulic application. Hydraulic hose and fittings have smaller IDs than
 oil hose, for the same hose OD and fitting thread sizes, and you'll get
 much greater pressure loss in the lines.

  Cheers,
 Theo
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