Oil pressure sensor question

[Scuderia]

Okay so I’m installing an aftermarket oil pressure sensor/gauge. The pressure sensor reads absolute pressure, from 0 psi to 145 psi. With the gauge it’s possible to calibrate it so it reads 0 psi at sea level, as opposed to 14.7 psi.

My question is when I’m at altitude say 7000 feet, will the oil pressure read a little less? At sea level my pressure at idle is 23 psi In other words does atmospheric pressure affect the pressure created by the oil pump inside the oiling channels?

This is the gauge I’m installing btw. Both pressure and temperature.

 

[brianl703]

The sensor should read oil pressure accurately regardless of barometric pressure. It's designed that way.

 

[JohnnyG]

That one appears to be more elaborate. IF in fact it reads 14.7 psi @ sea level as the OP says.
I'd say it's a bit of overkill, but if you have it, RTFM.

 

[atikovi]

Okay so I’m installing an aftermarket oil pressure sensor/gauge. The pressure sensor reads absolute pressure, from 0 psi to 145 psi. With the gauge it’s possible to calibrate it so it reads 0 psi at sea level, as opposed to 14.7 psi.

This makes no sense. Why would it read 14.7 psi at sea level. With the engine off it should read 0 psi at sea level or on Mt. Everest.

 

[brianl703]

This makes no sense. Why would it read 14.7 psi at sea level. With the engine off it should read 0 psi at sea level or on Mt. Everest.

Maybe it's a barometric air pressure sensor that identifies as an oil pressure sensor.

 

[atikovi]

Maybe it's a barometric air pressure sensor that identifies as an oil pressure sensor.

Oh great. Now we got trans gauges?

 

[Scuderia]

This makes no sense. Why would it read 14.7 psi at sea level. With the engine off it should read 0 psi at sea level or on Mt. Everest.

It reads absolute pressure, or at least it’s capable of. Out of the box it will read 14.7 psi of oil pressure with the engine off. You have to calibrate the gauge so it reads 0 PSI at your current altitude/pressure.

What I’m trying to figure out is if this sensor will read oil pressure accurately at altitude. But my bigger question really is how does altitude affect oil pressure? Does it stay the same regardless of the pressure? Or does it gradually down as you climb?

 

[atikovi]

It reads absolute pressure, or at least it’s capable of. Out of the box it will read 14.7 psi of oil pressure with the engine off. You have to calibrate the gauge so it reads 0 PSI at your current altitude/pressure.

What I’m trying to figure out is if this sensor will read oil pressure accurately at altitude. But my bigger question really is how does altitude affect oil pressure? Does it stay the same regardless of the pressure? Or does it gradually down as you climb?

No idea, but then you have to ask, does oil boil at a lower temperature at altitude like water does? The cooling system is sealed so that raises the boiling point. Isn't the oiling system sealed as well? No I don't think it is.

 

[Scuderia]

No idea, but then you have to ask, does oil boil at a lower temperature at altitude like water does? The cooling system is sealed so that raises the boiling point. Isn't the oiling system sealed as well? No I don't think it is.

Yeah I never gave it thought until I bought this setup. Well the oil system is partially sealed from the oil pump compressor to the exits holes on the bearings and cam shafts. In that area it’s pressurized varying amounts.

But I did figure out I bought the wrong sensor type. I need a “gauge” sensor and not an absolute sensor. Luckily I have a spare 5 volt gauge sensor.

 

[Oro_O]

Apples-to-apples (weather independent), you lose ~2 psi every 5k feet at most altitudes you will encounter WRT atmospheric pressure.

0 ft. - 14.7psi
5k’. - 12.2psi
10k’ - 10.1psi
15k’ - 8.3psi

This won’t matter for your application. Calibrate it to zero where you live and then don’t worry about it.

Here is a comprehensive chart:

https://www.mide.com/air-pressure-at-altitude-calculator