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Re: [Tigers] Oil Pressure

To: <tigers@autox.team.net>
Subject: Re: [Tigers] Oil Pressure
From: "Dave Munroe" <dave@munroe.ca>
Date: Mon, 2 Aug 2010 15:21:39 -0300
Dr. Mayf:

You make a lot of good points.

First, I will test my gauge as the next step.

The remote filter does have lots of places where the various fittings and 
twists and turns can reduce flow and as you have explained, reduce pressure. 
But I wonder if other Tigers that have either the original or aftermarket 
remote filters fitted suffer the same pressure loss?

We have asked owners to report in the past on their oil pressure, but it 
seems only those with 60 to 70 psi come forward with the info. perhaps there 
are lots of others like me who have Tigers with this level of oil pressure, 
but don't want to talk about it! It just seems unlikely that a stock gauge 
would be fitted with a gauge that reads all the way to 80 psi, with 50 in 
the center, if "normal" was 30 to 45 psi. As humans, we naturally like to 
see gauges with the needles "in the middle" of their range, or higher, but 
lower kind of gets the anxiety juices flowing, at least with me!

I only have a little over 300 miles on the engine since re-installation, so 
the oil that was in the engine on the dyno is still in there. I plan to 
change it at 500 miles. It is 10-30 Castrol. In the engine before the 
re-build I tried oil viscosities up to GTX 20-50 with no change in the 
readings on the gauge.

The dyno O.P. line was taken off at the same place as the stock line is 
attached. It was connected to their mechanical gauge by a flex hose, much 
larger in dia. than the stock line.
The shop didn't use the remote line because it was easier to just screw a 
large filter onto the block.

On the dyno in stripped configuration, the engine made 450 ft lb torque at 
5,100 rpm and 317 hp at 5,500 rpm.
Its a nice street engine.


Thanks for your thoughtful reply Dr. MayF.

Dave



> 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
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