Sylvain2000

For those who were following this ,

Finally put my oil pressure sensor back to the sandwich plate and my pressure reading is back to "normal".

So ... From my experience !!

Oil pressure at the oem oil pressure sensor location with oil around 200 degres is 75 ish psi at wot no vtec and drops to 65 ish psi in vtec

Same oil temperature at the oil filter (sandwich plate) as a steady 90psi with a lite dip at vtec engagement.

ckowalc

Here are my readings from a basically stock OEM 2005 S2000:

Car: F22C
Mods: OEM (stock oil pan, stock radiator, etc)
Oil: 10w30 Pennzoil Platinum Synthetic
Water: 50/50 Honda Coolant and Distilled Water

Oil Pressure:
@Idle; Start up (67 F): 85-90 psi
@Idle; At Temp (176 F): 18 psi
@3000RPM, Stable Throttle (176 F): 82 psi
@WOT (176 F): 82 psi, and 10 psi drop when in VTEC

Oil Temp:
Interstate: 170 F (65 F ambient)
Track (VIR): 263 F Max (53 F ambient)
Track (AMP): 273 F Max (91 F ambient)

Water Temp (70 F ambient):
Track: 195-200 F
After coming to a stop: 225 F Peak

My sensor locations:
Oil pressure – OEM Oil Pressure Switch port
Oil temp – Oil Drain Bolt (Oil Pan)
Water temp – OEM sensor (using OBD II data)

Here is how oil pressure varies with oil temperture throughout a session:


And here's one of my laps at VIR logging coolant temp, oil temp and oil pressure. You can clearly see the 10 psi drop when going into VTEC.

Here is the service manual's recommended minimum oil pressures as noted earlier in this thread. I was initially concerned with my idle oil pressure reading until I found this thread. I wonder if this is a typo in the manual?

ckowalc

Also, for those interested, here is my setup:

Oil Tempertaure:

• Oil Drain Plug Adapter ($10): Universal Oil Temp Adapter - Drain Plug - 42 Draft Designs
• 1/8 NPT Thermocouple Probe ($7): K Type Thermocouple Temperature Probe Sensors for Measureing Motor Water and Oil | eBay

Oil Pressure:

• 1/8 BSPT to 1/8 NPT adapter ($10): https://www.mcmaster.com/#4092k11
• 100 PSI 5V Pressure Transducer ($16): Pressure transducer or sender, 100 psi (5V), for oil, fuel, air, water | eBay
• 12V to 5V Step-down Voltage Transformer ($6):
  Amazon
  Amazon

I left my OEM pressure switch disconnected (no, this does not cause the oil pressure light to come on). I didn't want to tap into any 5V sources so I ran power from the battery. I noticed after the fact that they sell a 12V 100 PSI pressure transducer which would have made things easier: Pressure transducer sender, 100 psi 12V (10-25V wide), for oil,fuel,air,water | eBay

I used a data logger from work to record tempertures and pressures on track. The coolant/water temp data I collected using Harry's LapTimer using a bluetooth OBD II dongle.

One thing I will mention is the pressure readings are a bit noisy (about +/- 5 psi at 80 psi). I'm not sure if that's because of the cheap eBay sensor, my wiring, or oil pressure is supposed to look like that. For the video, I smoothed the data by running it through a filter. Looking at other data in this thread, it does seems like other people's pressure data is a little noisy as well.

spdracerut

Your values are a bit on the low-end. Your idle pressure especially low. But your values at 3krpm and WOT/VTEC are representative of what people see. I measured my oil pressure at a sandwich plate before the oil filter, so before the pressure drop of the oil filter and the flow path up to the OEM port. With oil temp around 90C measured at the sandwich plate, I'd see about 1.8 bar/26psi oil pressure at idle. 3k rpm, 6+ bar/87psi+. Coming off track with an oil temp of 240F, I'd still see an oil pressure of 1.6-1.7 bar using Motul 5W-30. Mobil 1 is garbage and would thin out significantly, down to like 1.2 bar. I'd also see the oil pressure fluctuate quite a bit very rapidly, roughly +/- 3psi.

Part of your results is your oil temperature location. The aluminum finned oil pan does a good job of cooling the oil. Where you're seeing 170F on your interstate drive with 65F ambient, I'd see 194F measured at the oil filter sandwich plate. The oil pressure at idle is a bit concerning... maybe try a different oil?

I have a theory as to why many people see lower than service manual spec oil pressure; I think the pressure relief spring gets a little softer over time. I'm thinking of replacing the spring in my oil pump or possibly shimming it. Shimming will only help with the oil pressure at higher engine speeds though. At low engine speeds, it seems to be driven mostly by bearing clearances. Worn out/loose clearances = lower oil pressure.

SlowTeg

I don't recall my idle oil pressure, but I'll have to measure it and make note. I don't think high teens is low though at ~170F..? Mine might be very low 20's, but not more than that I believe. Perhaps I should keep an eye on oil pressure over time, it'd certainly be interesting to see if it has a strong correlation with bearing clearances like you said Khiem. Shimming the oil pump is something I've definitely thought of as well, but it's a real pita to pull the pump. Having a little higher oil pressure for track cars sounds like a good idea.

Here are my pressures on 10w30 Castrol gold bottle:
Pre-oil cooler:
220-230F oil temp: 75psi in vtec
~260F oil temp: mid to upper 60's psi in vtec

Mishimoto oil cooler:
220-230F oil temp: 68psi in vtec

Oh ya, I also meant to comment, I wonder what the pressure difference is at the oem pressure location vs the oil filter. My measurements are at the oem sending unit location vs oil filter. It'd be interesting to try a back to back comparison of the different locations on the same car..

ckowalc

Based on peoples replies in this thread it seems high teens or low 20's is normal. There are a few people with pressures in single digit or low teens range and then robrob with 33 psi idle. I don't think a single person has said they had idle oil pressure (at 176 F) of 36+ psi. I'm unsure of what the pressure differential would be at the OEM oil pressure switch location vs. at the oil filter but the test method in the service manual is using the pressure switch location.

SlowTeg

FWIW, I took a look at my oil pressure the other day and at 176F am seeing 23psi. This is with an idle of ~900rpm. I just wanted to post this for reference for anyone else any myself down the road. My engine has ~49k miles on it currently. I'm running a 200F Mishimoto thermostat. I could see a 185F thermostat probably being open more and lowering oil pressure at idle..? Just an idea..

johnckeen

Just fitted new relocation kit to my car 2003 133k miles on clock with HKS charger.
Idle (80c) - 42-45psi
4krpm at 60mph - ~90psi
around 105psi just before vtec, then drops 3 or so psi but recovers straight after back to ~105psi.

Really hard to watch the gauge when doing this ha.

Jabneel Perez Colon

I have a aem gauge and when I put it on it was winter! “I’m from Florida” and these past week it’s been over 95 degrees out and my pressure dropped from 31-33 at idle fully warm to 25-27 is this normal because of the temperature out ?

ryanmdel

Probably just the temp change but I'd also check your oil level, my pressure goes down a few psi if I'm a 1/4qt low from full. I think most people including myself idle in the 20s when warm, so it's nothing to worry about.