Dave, several things come to mind. One is, of course, the in dash
pressure gauge. See if you can rig up a second gauge for a direct
comparison. But, there are other issues as well. If you have the stock
remote oil filter setup, then the adapter at the block receives the oil
and makes a hard right turn headed to the filter. It must pass the hose
to adapter fitting, the solid part of the hose to "rubber" hose
connecion twice and then flow though another hose fiting at the filter
adaper and then make another hard turn going into the filter proper.
Ther filter to engine comes straight out of the filter through a
fitting, then through the similar hose, with its losses, then into the
block adapter. So, there are a number of places where the flow can be
reduced. reducing the flow on the down stream side reduces the
pressure. Also, did the dyno shop drain the oil and you put in a
different viscosity? If so, that will change the flow and pressure
also. Did you use the same oil brand and weight? When they had the
engine on the dyno, how big was the mechanical gauge pressure line or
was it screwed directly into the engine? The dinky oil pressure line
that runs to the dash gauge can cause some pressure losses. It would
have been interesting if the shop had used your remote filter set up on
the dyno. Why didn't they?
just some things to think about...
mayf
Dave Munroe wrote:
> Ok guys, the mystery continues.
>
> I have sought advice here about oil pressure and we have discussed
> this before. But now more intelligence has been gathered.
>
> My engine was built by a well meaning but as it turns out,
> inexperienced Brit mechanic in 2005. Amongst more serious problems,
> my engine's oil pressure also was below what I have come to believe is
> "normal" pressure for a fresh, quality re-build.(50 to 55 psi cold, 40
> to 50 psi hot with 10-30W oil). I was tired of, and concerned with,
> the O.P. gauge showing the needle far to far to the left of center.
>
> I had my engine removed and "blue-printed" by a knowledgeable and
> highly regarded local shop. They found and corrected the other, more
> serious problems, and when reassembled, put it on their shop dyno.
> During the rebuild they installed a new, standard oil pump on the
> recommendation of many on this list who responded to my earlier
> inquiries, to replace the high volume pump that I had installed in the
> first re-build.They also installed a large filter directly on the
> block for the several pulls the engine went through on the dyno. They
> had hooked-up a mechanical oil pressure guage and a transducer that
> fed into their diagnostic computer. My engine was showing 70 psi at
> 1500 rpm, and it rose to 75 at 5500 rpm (redline).
>
> Back in the car with the remote oil filter set-up, with new, large
> diameter hoses fitted, it shows 45 psi cold, and 25-30 hot at 3,000 to
> 4,000 rpm. I am at a loss to understand how the remote filter set-up
> could possibly cause this drop in indicated pressure. The only other
> variable is my pressure gauge, which is nothing if not consistent.
>
> I will appreciate any wisdom or suggestions as to what is going on and
> how to correct this low pressure problem.
>
> Thanks for your help,
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