truth.b

Currently, I log Engine Oil temp during my HPDE sessions using the Torque Pro App via Bluetooth OBDii adapter. I log Oil Temp PID: 221154, equation: A-40.. Last event I noticed there was about a 30* delta in what the DIC said oil temp was and what I was logging. At one point the app registered 235*F for engine oil but the DIC stated 266*F. At the time of these measurements my records state an Ambient of 98*F and an Intake temp of 107*F.

Questions:

• Does anyone know exactly how oil flows through a Dry-Sump LS3 engine and where along in that path oil temperature is measured?
• Is engine oil temp measured in two places?
• Are the two oil temp readings I saw trustworthy values?
• Is the oil entering the engine the lower value and that the dry sump the higher?

My assumptions are that the oil measured at the engine is the 230*F and the oil measured in the dry-sump tank is 260*F. This is because since the event I've watched the OBDii temp reading come up to temp normally in street driving while the DIC reading take several additional miles to come up to match operating temp.

So far I know #18 in the bottom picture is a temperature sensor but I'm not sure to which number it reports to.

Oil Cooler:
Link: Engine Oil Cooler & Lines


Dry Sump & Lines:
Link: Dry Sump Lines & Mounting



Dry Sump Tank:
Link: Engine Oil Tank ASM

wstaab

Oil temp sensor is located in the bottom of the oil tank (part 18 in diagram). That is what is displayed on the DIC. Not sure what PID 221154 is. Does not look like a GM PID value. There is a PID for calculated oil temp that is generated by the ECU but it is not as accurate as the actual oil temp sensor in the tank. The oil temp measured by the sensor is oil going to the oil pump from the oil tank. That is the only oil temp sensor in the system.

truth.b

Thanks for the response. Do you know at what point the oil passes through the oil cooler?

wstaab

truth.b

Thank you for the diagram. This makes me feel that the oil temp reported by the ECU via OBDii PID is representative of what's entering the engine. My assumption is a 30* temp drop across the oil cooler seems reasonable when reaching +135MPH twice per lap.


For the record my understanding of flow is:
DrySump Tank >> Oil Pump >> Oil Filter >> Bypass Valve (closed @ track temps) >> Oil Cooler >> Engine / Sump Pan >> Oil Pump >> DrySump Tank

bjmsam

That is consistent with what I posted here.

Then why do the DIC and PID values differ, and why is that difference non-linear? The chart shows how the DIC reflected the effect of my dry sump tank preheater while the PID did not; how can this be?

Immediately following a recent drive (to log the data for this chart), the OBD PID reported ~155°F, the DIC displayed ~185°F and my IR thermometer aimed into the dry sump dip stick hole read ~195°F. My oil cooler thermostat opens at 180°F.

Here is what I observed yesterday with the car cold in the garage:
41.0°F (IR thermometer at top of dry sump tank)
39°F (oil temperature displayed by DIC)
39.2°F (oil temperature reported by OBD with PID formula A-40)
37°F (coolant temperature displayed by DIC)
37.4°F (coolant temperature reported by OBD)

blkbrd69

There are 2 different OBD2 readouts. One is calculated, the other is actual value off the tank assuming your sensor is good.

My DIC reads the same as my datalogs.

Verified mine with a multimeter pyrometer dipped deep in the tank hot.

Chevy is notoriously bad about calculated readings. I would be happy with 260 and ecstatic about 230. The problem is its easy to fly over 300 in the summer on track in warm climates.

If you want warm oil in a freezing climate the ZR1 oil warmer is the only real option, unless you plumb in a water/oil heat exchanger like the Cadillac Pirelli World challenge car uses. See my post on track coolers. Post #110

https://www.corvetteforum.com/forums...cussion-8.html

However even it is marginal for a track car. Its a no win, the stock systems are not near enough cooling for a track car, and too much for the street.

bjmsam

How are you reading the actual value of the oil temperature sensor via OBD other than PID 221154?

blkbrd69

Autocal EFI Live w wideband for my data logging. Shows as EOIL *F

Chets LS3

Not the same, but maybe some help. Mine is on an IR oil cooler adapter. I have oem on the "cooled" oil coming in and the aftermarket gauge on the hot oil going out. I usually see 15*-20* variance.

Erik L

I think the difference between the Sensor reading at the bottom of the tank, the calculated reading that you see on the dash and the reading on your Infrared temp checker is the Infrared temp checker. I bet the margin of error is enough on the tool to give those readings. At my work we use the tools to verify temp around 500 deg F. Its a constant discussion about calibrating the tool at the 500 deg point. If we use 5 different tools we get 5 different readings. IIRC 40 - 50 degree range is routine. It really needs to be calibrated around the temp you are using it. i.e. you can't calibrate on a piece of ice and expect the calibration to hold at 300 degrees. The tools are great to give you an idea of temp or show you a change in temp say across a tire width. Not ideal to hang your hat on the exact temp.