Oil pressure switch (warning light)

[(2much)]

Hey guys,

Just been wondering if the oil pressure switch in the block does anything except run the light on the dash.

I want to replace the stock oil pressure switch with a low pressure switch so the light can come on as a warning. Rather then a cooked engine indicator.

Perhaps I'm over thinking things.. Or like George had setup in his e2, a second hobbs sensor.

What is a low oil pressure? In hot engine idle conditions, can you buy a 5 psi switch? What is the stock switch rated at?

Thanks guys

 

[4piknup]

Loaded question, low oil pressure.
Depends, if there is no load and very low engine rpm then there doesn't need to be any oil pressure at all (that's why those engines with nulon type additives can idle for ages) but as rpm and power go up, you need more oil and more pressure...
So if a standard oil light flashes at idle when hot, it doesn't mean that it is getting damaged (though it indicates that the bottom end has pretty major issues already), but if it is on during acceleration, you have big problems.
Scientifically, you need enough oil to stop the bearing surfaces touching, this would be done by oil analysis, I guess you start high and keep reducing oil pressure or volume or viscosity until you start to see a increase in bearing particles in the oil samples...
That's as good as I can get without actually answering any of your questions.
Yep oil sender only runs the oil light, but on nissans it also is needed as a failsafe for the fuel pump, so if no oil pressure then no fuel pressure either (unless cranking).

 

[bazeng]

It would have to be a variable config...

ie.

1000rpm = 10psi
2000rpm = 20psi
3000rpm = 30psi
4000rpm = 40psi
5000rpm = 50psi
6000rpm = 60psi
7000rpm = 70psi
8000rpm = 80psi
9000rpm = 90psi

Now if you had a 5psi warning sensor and the engine is revving at 9000rpm, your engine is cooked!

You would need to configure an analog sensor that outputs 0-5v's pending pressure. With this you can then (depending on rpm) determine what pressure is safe based on your engine speed.

So if the engine is spinning at 9000rpm and your pressure is 80psi, it will warn you...
If spinning at 5000rpm and your pressure is 40psi, it will warn you..

So it becomes quite complex.

You can do this easily with a good datalogger (MOTEC SDL / ADL etc).
You can also do this with a good ECU (AUTRONIC / MOTEC etc).

I run this type of warning setup on my MOTEC SDL.

If you want to keep it mechanical (no logger).... I can only think of still using an analog sensor, map out the pressures or obtain the calibration details somwhere and display the voltage with some form of voltage gauge (0-5v).
From this, you can either learn what is a good voltage / bad voltage.

Or a crappy but basic method.

Use 2 pressure switches. One that activates at 10psi and the other at 50 psi.
Use an RPM trigger to activate a relay that switches between the 2 pressure switches.
So under 5000rpm it uses the 10 psi switch, once it goes above 5000rpm, the relay switches to the high pressure switch and it then uses the 50psi pressure switch.

My thoughts anyway.

 

[4piknup]

I'm going to go off on a tangent seeing as we are talking about early warning systems, idiot lights and sharing thoughts.
I was thinking of a water pressure light. As if you losing water fast you will drop water pressure before you cook your engine. Radiators run at 1bar ish, so a 5psi pressure switch that becomes live once engine becomes warm.
Simple and effective.

Also it a pity that my stereo DVD/gps won't talk to the ecu or you could set up all sorts of condition monitoring and screens

 

[(2much)]

I like your thoughts baz, I am not running such a high state of tune, I don't want to run a gauge, but I wouldn't mind the safety of an early warning system Albert simple