Good Oil Pressure?

Lowtechprime

Lowtechprime

Retro Grouch
What is a good oil pressure for a 1500? The search tool omits 3 letter words like 'oil' so I apologize if this has been covered somewhere.
 
Any pressure is good pressure.
The factory spec is a very large range, I don't have it handy right now.
And the stock gauge is not to be trusted, usually reads low.
 
I use mechanical gauges and see 40-50 psi at running speeds, about 20 at idle. Obviously the hotter the oil gets the lower the pressure. I like Ulix's response, any pressure is good pressure!
 
As a footnote here: It is general principle that you typically want 10 lbs per 1000 rpm of oil pressure for performance applications and for the average street engine you want a minimum of about 25 to 30 psi at idle. These would be hot pressures (195 F).

Every X1/9 oil pump I ever instrumented, on a healthy, stock, engine had about 20~25 at idle and 55~60 at redline. For my fully blueprinted DSP engine (OE Crank, Rods, etc...) it idled at about 15 psi at (1200~1300 rpm idle speed) and maxed at 75 psi at about 5500 rpm. It used an OE relief spring with a small shim to up the pressure slightly. Important to note this was using 5w30 synthetic. I am sure that 20/50 would yield a higher idle pressure.
 
Hmmm... Mine seems high then? As you can see, I've got about 53 psi at 190°, at around 1,000 RPM's.... Amsoil Z-Rod 20w50....
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Low oil pressure has worried me for a long time. I had no oil pressure sender on my 1500 (probably a Ritmo/Strada engine) so I have nothing to refer to, but my UT engine has 1-5 bar over the rpm range with 15W50 fully synthetic oil. I think this is a little bit low, but other UT owners tell me it is normal. Some people have a shim on the relief spring. How thick is that? Can they be bought?
 
I think the general feeling about the Fiat electrical oil pressure gauge is that they are whimsical at best and I went by the theory that if the needle twitched at all then I had pressure! It's why I always use a mechanical gauge.
 
Yes, the gauge and sender should not be considered the benchmark. Consider the electrical system issues with headlights, wipers, blowers, etc... and apply that knowledge to the oil pressure gauge.

The sender is just a simple potentiometer moved by a rubber diaphragm and designed to be inexpensive first and provide moderate accuracy second. The same applies to the gauge.

If you are curious about what your actual oil pressure is, buy a mechanical test gauge, remove the sender and temporarily install the gauge. Start the car and let it warm up. Then note the pressure at idle and as rpm rises until the pressure stabilizes. Its pretty easy to plot the pressure at 1000 rpm increments and see what your pressure profile looks like.

Incidentally, you can have too much pressure. Excessive pressure can cause loss of engine performance (although not likely noticeable to the driver). It can also cause the pump to cavitate and damage itself. There is really no reason for having pressures significantly above the 10 lbs/1000 rpm baseline.

My DP MR2 (Toyota 4AGE) is regularly run to its 9200 rpm shift point with a max oil pressure of 90ish PSI.
 
Steve Hoelscher said:
Yes, the gauge and sender should not be considered the benchmark. Consider the electrical system issues with headlights, wipers, blowers, etc... and apply that knowledge to the oil pressure gauge.

The sender is just a simple potentiometer moved by a rubber diaphragm and designed to be inexpensive first and provide moderate accuracy second. The same applies to the gauge.

If you are curious about what your actual oil pressure is, buy a mechanical test gauge, remove the sender and temporarily install the gauge. Start the car and let it warm up. Then note the pressure at idle and as rpm rises until the pressure stabilizes. Its pretty easy to plot the pressure at 1000 rpm increments and see what your pressure profile looks like.

Incidentally, you can have too much pressure. Excessive pressure can cause loss of engine performance (although not likely noticeable to the driver). It can also cause the pump to cavitate and damage itself. There is really no reason for having pressures significantly above the 10 lbs/1000 rpm baseline.

My DP MR2 (Toyota 4AGE) is regularly run to its 9200 rpm shift point with a max oil pressure of 90ish PSI.
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I definitely agree you can have too high oil pressure. I was just being facetious earlier with my comment otherwise. However I do not feel the pressures noted by @Lowtechprime are anywhere near too high. And that was my point. ;)
 
Lowtechprime said:
Normally, all my cars have all mechanical gauges. But for this one, I wanted the Factory Rally look so.......🧐
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I trust electric gauges/senders made by another company, in another country. In my personal experience they are very accurate. It seems to be the ones Fiat used that are not. However we need to consider the type of gauge as well - often the smaller sweep of a factory gauge mounted as part of a instrument cluster is not as effective as a full sweep/full size round gauge, like aftermarket items or part of a "performance" package with extra gauges.
 
Found a Bosch Motorsport pressure/temperature combo sensor that can replace my oil temp sensor. That way I can have all accurate information in the ECU and Android Pad with virtual gauges. This means I can also create a rule to automatically shut down the engine if oil pressure falls under a critical level. I really like Bosch Motorsport products, they are a little bit pricy but high quality products. I will leave the stock sensor/gauge as is for comparison. However, I need to add two more cables (5V sensor supply and oil pressure signal) to the wire harness tube which will be a PITA to get in. -I regret I didn't do it this way when I built it.
At the same time I will add a bigger wire for the new intercooler water pump that draws much more power than my current pump.
 
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