Gages used in automotive applications are wildly inaccurate. They err on
the high side for the most part. They are all pretty much based on amperage
flow through a coil wrapped around a moving magnetic armature. The higher
the current flow, the further the armature moves and the higher the needle
registers. Sending units are a variable resistor. Usually 0 ohms to 80 or
90 ohms. As the resistor varies, so does the current flow. That flow goes
through the gage, and moves the needle. Simple, cheap, and accurate enough
for most uses.
My personal opinion on gages is that your eyes should be on them as
little time as possible. Same goes for navigation devices. You should be
looking down the road, not worrying about what the gages are saying.
That is why the indicator or warning type of instruments make sense.
They flash a warning or an audible alarm when something's so far out of
range that action is required. Digipanel is one type.
Some coach owners use both types. Spend your money the way you see fit.
Jim Hupy ( extra gages include vacuum, tachometer, transmission pan
temperature, and final drive lube temperature. )
Salem, Or.
On Wed, Nov 21, 2018, 7:03 AM Charles Boyd
wrote:
> Hi Ken.. I personally have had issues with engines with low oil pressure
> and I freak out if I see less than 1/2 . I currently have a OEM gauge and a
> Bosch manual gauge. 35 on the manual gauge is one needle width past 1/2
> on the OEM gauge and I love it.. cold it is 55 and 3/4. Hot ( towing in
> hills 205* or so). It is 30 and 1/2 on OEM gauge.
>
>
>
>
> > I would go with the 80. Here is my logic. On a cold engine the PSI
> will reach 60 and the oil pump bypass will kick in that means the the gauge
> > will read 3/4 scale. On a hot engine the pressure will read 40 PSI at a
> couple of thousand RPM cruising down the road or about 1/2 scale. At an
> > idle the PSI will drop to something 1/4 scale or better. Going to 60
> will change those readings to even higher on the gauge.
>
>
> --
> C. Boyd
> 76 Crestmont
> East Tennessee
>
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