Observed Oil Pressure with a gauge

Rusty

As the title says. There has been a lot of talk on oil pressure lately. So the more info we can get. The better informed we will be. So post up. The more info, the better.

Gauge - SpeedHut 0 to 150 psi.
Sensor location - Tee'd with the factory sensor. Different location will give different reading.
Oil - Mobil 1 0w40. Different weight oil may give a different reading.
Oil Cooler - Z1 34 row.
Oil Temp when warm - 180F.
Engine temp when warm - 185F.

These are are the oil pressures at different rpms that I observed. Using 3rd gear. Giving the throttle just enough to get to the rpm and hold it there for about one minute.

Cold Start - 65F outside temp. 104 psi dropping to 48 psi after about 3 minutes
Cold Start - 82F outside temp. 93psi dropping to 48 psi after about 3 minutes.
Warm Idle - 38 psi
2,000 rpm - 75 psi
3,000 rpm - 87 psi
4,000 rpm - 93 psi
5,000 rpm - Goes to 102 psi then drops to 93 psi
6,000 rpm - Goes to 104 psi then drops to 93 psi
7,000 rpm - Goes to 105 psi then drops to 93 psi
7,500 rpm - Goes to 105 psi then drops to 92 psi

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Here's my input:

Gauge: Defi Red Racer 0 - 1,000 kPa (0 - 140 psi)
Sensor Location: On oil filter sandwich adapter plate (non-thermostatic)
Oil Cooler: None
Oil: Nissan Genuine Ester Oil 5W-30

Cold start - ambient temp. 27C (80F)
Initial reading: 760 kPa (108 psi)
After 1 minute: 500 kPa (71 psi)
After 2 minutes: 390 kPa (56 psi)
After 3 minutes: 340 kPa (49 psi)

Oil temp. 80C (180F)
Idle (no load): 190 kPa (27 psi)
1000 rpm (no load): 270 kPa (39 psi)
2000 rpm (no load): 440 kPa (63 psi)
3000 rpm (no load): 700 kPa (100 psi)

Oil temp. 92C (198F)
Idle (no load): 140 kPa (20 psi)
2000 rpm (3rd gear): 380 kPa (54 psi)
3000 rpm (3rd gear): 600 kPa (86 psi)

FYI: FSM lists oil pressure specs as follows:
Oil temp. 80C (180F)
Idle (no load): more than 98 kPa (14 psi)
2000 rpm (no load): more than 294 kPa (42 psi)

MotorvateDIY

This is a great idea! I will add my results in a few days.

If your pressure sensor mounts in a sandwich plate, you are measuring the oil pressure going INTO the oil filter. This reading will be higher than the actual engine oil pressure, since it takes some pressure to push the oil through the filter.

If your pressure sensor is mounted in the factory location, you are measuring the oil pressure AFTER the oil filter.

On a future episode MotorvateDIY Garage, we will show how much pressure it takes to push oil through the oil filter.

dts3

Sub'd.

I should have something to add once my adapter fittings for my pressure sensor arrive.

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Interesting. I can only share my experience. Initially, I installed an AEM oil pressure gauge (0-150 psi) based on a DIY posted by Spearfish some time ago. I removed the factory sensor and replaced it with the AEM sensor (I didn't bother installing a tee fitting to accommodate both sensors). With that set-up, I would see a reading of about 90-100 psi on a cold start, which dropped rapidly as indicated above by Rusty. At operating temperature (200F), I would see a reading of 18-20 psi at idle (no load). I can't recall exactly what the readings were under load at operating temperature, but they varied from about 70-85 psi at 2,500 to 3,000 rpm in 6th gear. I was running Motul 8100 X-Clean 5W-30 at the time. The next year, I switched to the Defi Red Racer Gauge (see above) since I preferred its appearance and it seemed to be more reliable. I re-installed the factory sensor in its original location and installed the Defi sensor on the oil filter sandwich plate (see above). I continued to run with the Motul oil (... only switched to the Nissan Ester oil at my last oil change when I took the readings shown in my earlier post). Anyway, I didn't notice any remarkable difference in readings after switching the sensor location. In fact, the readings remained virtually unchanged. I still continued to see a reading of 20 psi at idle under no load at operating temperature (200F).

mults

I see a red light with the engine off and no light at everything else .

Seriously, I have a 150# gauge that I need to install on the A Pillar, so at least now I know what I should expect to see.

This is a great thread..

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dts3

Did you get any DTC / dummy light when you were running without the OEM pressure switch?

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No.

dts3

This is interesting. I've been putting some effort into trying to maintain the stock pressure switch (waiting on the T-fittings is why it's not done yet). If I can just delete the OEM switch and put the defi sender into the hole (with a BSP->NPT adapter), it will save me some headache. I'll also sleep a little better at night without worrying about two sensors hanging off of a tee, bouncing around on the highway. Thanks for sharing that.

dts3

What was the reason for moving from the factory location to the sandwich plate?

Rusty

There is no issues with installing a tee. The only thing you have to worry about is how you clock it to position the sensor.

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"The Difficult Anytime, The Impossible By Appointment Only"
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dts3

I understand many people have used tees with no problem, but I tend to worry unnecessarily about things. It's one of my personality flaws that I've learned to live with

MotorvateDIY

I don't like the "Tee" fittings either. I worry if the belt breaks, it could snap the oil off pressure sensor.

Here is a preview of a future episode "Making an Inexpensive OLED Oil Pressure Gauge"
It uses an Arduino Uno clone, 128x32 OLED display and a 150 PSI digital pressure sensor.

Attached Images

two.jpg (141.3 KB, 675 views)

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Two reasons:
First, I was looking for some redundancy. By re-installing the factory sensor, I had some back-up in the event that the Defi sensor/gauge ever malfunctioned. It was for ease of mind.
Second, the Defi sensor is configured such that it can't be installed using a socket (standard and/or deep). It becomes obvious why once you have it in your hand. And, I found that there wasn't enough room to tighten it into the factory port using a standard open-ended wrench. You might be able to install it using a crow-foot wrench ... but I opted instead to simply purchase an oil filter sandwich plate and install the sensor in one of the ports in the plate. I had to purchase an adapter since the female port thread was 1/8 NPT and the male sensor thread was 1/8 BSP (i.e., the Defi sensor thread is metric).

dts3

That's cool; I like the redundancy. Ideally I'd like to run a separate sandwich plate for the sensors, but with the combination of the Z1 cooler sandwich plate and the oem oil/water "cooler", I don't think I'll have enough room left for the filter (and I don't want to relocate at this point)

It's interesting that your Defi gauge is 1/8 BSP; which do you have? I have the Defi BF Advance, and the manual is saying it's 1/8 NPT.