All production car has a filter element by-pass feature in the oiling
system. In some engines this feature is built into the oil filter itself
(many spin on filters have a filter by-pass valve built in), in other
engines, thios feature is designed into the engine's oiling system. The TR-4
has the filter by-pass built into the aluminum block that bolts onto the
side of the engine, Datsun (NIssan) "L series" engines have a filter by-pass
valve on the side of the block, the Jaguar XK series engine has separate
oil filter and oil pressure valves both mounted in the alloy "filter
adaptor" on the right side of the engine.
Is is my understanding that the filter by-pass valves are usually set to
open and "by-pass" oil around the filter element at somewhere between 4 & 9
psi depending on the designer specifications.
I have never seen any test results of how much pressure differential could
cause filter collapse or leakage of unfiltered oil or of what the
differential pressure might be based on oil temperature, rate of flow, oil
viscosity, filter area, and the fineness of filtration. These would be the
variables.
The heavier the oil, the greater the flow, the smaller the filter area and
the finer the filtration, the greater the pressure differential. More square
inches of filter paper in the filter, all other things being equal, is
always a good thing.
It would be interesting to set up two pressure gauges on and engine with
the oil filter bypass blocked and actually read the difference in oil
pressure on each side of the filter with say, 50 sae, 20w-50 sae, 10w-30
sae, 15w-40 sae motor oils and chart the pressure differential vs. oil
temperature. This would give some figures so that the filter bypass valve
could be set to by-pass when the oil is cooler than 120 degrees F and always
filter 100% at temperatures above 140 degrees F. I would say that this
would be the ideal situation.
Greg
----- Original Message -----
From: "William G Rosenbach" <wgrosenbach@juno.com>
To: <RKramer@rdoequipment.com>
Cc: <WEmery7451@aol.com>; <vinttr4@geneseo.net>; <fot@autox.team.net>
Sent: Friday, December 01, 2006 6:52 AM
Subject: Re: [FOT] blow-ups
> What system does Ford or other manufacturers use that allows them to fit
> non-bypassing oil filters to their engines. The two styles of filters are
> clearly not meant to interchange as they have different threads. I bought
> a non-bypassing remote filter mount years back, but could not bring
> myself to fit it to anything designed to use a bypassing filter, and
> never sorted down what allowed for a non-bypass filter.
> Bill
> 70 GT-6+
>
>
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