I was on the track last saturday and I was paying attention to my oil pressure as some have seen drop in pressure on their car.

I saw the oil pressure in average in the 3 to 4 range, but on some turns I could see it drops in the low 2.

All this at relatively hight RPM, always above 4k RPM

Is that normal pressure ?

when at 2, the pressure would usually come back after 4 or 5 seconds.

I never looked at the pressure gage before...keeping my eyes on the road

Any confirmation on this topic would help.

My car is 2003 MkII 3.6 engine, base Carrera

see the video on youtube, oil pressure is not easy to see but you can tell when it drops


Phil

 

IIRC the factory manual calls out oil pressure at 5000 rpms to be (approx) 6 bar with the oil at 90C.

Two problems with the above. One you do not know the oil temp and two you do not know the oil pressure. The dash oil pressure gage is probably not very accurate. It is as is the coolant temp gage more an idiot light than a genuine trustworthy oil pressure reporting instrument.

The oil pressure at other lower rpms at 90C can be lower/will be lower but as long as the oil pressure warning light doesn't come on things should be ok. Should be. Generally if they are not the oil pressure light is a lagging indicator...

There are several variables... what oil were you running? How fresh was the oil? What was the oil temp? At the track the oil temp may have been (probably was) way hotter than 90C (194F).

Under hard driving on curvy mountain roads in 80F heat I've seen coolant temps of 226F ( but never hotter) in my Boxster and the oil temp has to be that hot or hotter.

So the chances are very good the oil temp was at least that high maybe higher in the case of your car.

As a point of reference in talking oil pressure over with Porsche techs they have told me that in the new DFI engines with variable oil pressure it is a bit unnerving at first to rev the hot engine and hold the revs steady and see the oil pressure go up as usual but then drop to around 3 bar.

But of course the DFI engines do just fine at this pressure.

The earlier generations of Porsche engines were fed oil at too high a pressure which wastes gasoline and heats the oil and this is one reason why variable engine oil pumps have started to come into vogue.

 

I am really looking for a good way to get precise oil pressure and temperature.

i saw some post on boxster forums but I'd love to hear feedback from 996 people as to where I can put sensors for those values.

http://986forum.com/forums/boxster-r...mp-sensor.html

With all the blown engine fear, I am surprised there are not DIY to install at least an oil temp gauge.. :S

 

BTW.

I am running less than 1000 miles 0W40 Mobil1 oil (oem recommended)
The water temp stayed right on the 180F mark, sometime the needle would go in the middle of the '0' digit, which I assume is 200F.
The track temp was in the 80F all day.

when oil pressure was low, I tried to see if releasing or pressing the gas hard would change anything, or even putting to neutral (clutch) and the pressure would not change much. I tried those exercise for only 1 or 2 seconds as I was on hot track

 

Install good gages. I installed an oil pressure gage in my 1st car, and 510 Datsun. Used a T-fitting to connect the oil pressure gage line to the same place the oil pressure switch for the low oil pressure warning light got its oil pressure from -- the main engine oil galley.

I installed a coolant temp gage but I do not recall now where I connected its sensor but probably at the same place -- with a T fitting -- the engine coolant temp sensor connected.

In the case of the 996 engine the oil pressure sensor is located at the top of one of the camshaft covers. This is where it is located on my Boxster engine, too. My Turbo's engine has a similar distant oil pressure sensor location.)

The techs point out this location is about as far away from the oil pump as it can be. It is this distance that has some nervous Nellies seeing a slight delay in oil pressure at engine start that has them in a panic the engine is operating sans any oil pressure. Sorry I digress.

Anyhow, you'd probably rig something up to take oil pressure from the same location or you could possibly pick up oil pressure -- maybe even oil temperature -- from some location (already tapped!) on the block that has you getting oil pressure/temp from a main oil galley.

 

Some coolant temp sensors/gages are pretty responsive -- relatively speaking -- and some aren't. You really can't know how hot the coolant temp is/was from the needle's position until you "calibrate" it by noting where it is and the how hot the coolant is using (as I have) an OBD2 code reader to view the real time coolant temp.

If you tell me the radiator fans were on the coolant was at least 212F and if the fans were on high the coolant was at 216F. My WAG is based on what I've observed with my Boxster and given you were on a track running the engine hard is the coolant temp was much hotter probably close to if not at 226F.

Oil temperature was at least as hot as the coolant and probably hotter yet.

Another consideration is the oil pressure sensor may just not be working very good. They've been know to fail, supply false readings. But before you replace this you probably want to verify the sensor's accuracy by comparing its reading to that provided by a known good gage. Or if the sensor isn't that much and that much trouble to change out just replace the old sensor with a new one.

 

using the OBD reader to check the value shown on the dashboard is a very good idea.

I'll see if my durametric can show me some good data.

what obdII reader to you suggest ?

 

If you have a Durametric it should be able to do what you want, at least regarding coolant temp.

Not sure if it can read oil pressure/temp from the engine controller. (My 02 Boxster doesn't provide an analog oil pressure reading. All the engine has is an oil pressure sensor that signals either no/or not enough oil pressure or some/enough (?) oil pressure.

I have a less sophisticated generic OBD2 code reader/data viewer from Actron that I use.

I use another device once in a while. It is one my employer produces/sells and one for which I'm the primary firmware engineer. I do not wish to name this product as it might seem like I'm touting it here.

There are other devices on the market, too, besides the ones I mentioned above.

Shop around. Ask around. Find out what others use on the track to gather engine telemetry of the type you wish to gather.

 

Phil, if you have an Android phone or tablet, you can get a mini Bluetooth obd ii adapter for $15 and get the Torque app for $5. Just search in Amazon and eBay. Torque has tons of features for diagnostic or entertaining purposes and it's so convenient to use.

No generic obd ii scanners can read the transmission temp though afaik.

 

I actually have the bluetooth for iphone thingy, calle bt1.

what is the full name of your app ? I looked for torque app and could not find anything obd related.

 

ohh I see this is android stuff
I am on the apple team lol

I'll look into it,

 

Consistent with what I saw the one time I tracked my 3.4.

 

Improve the weakest link 1st, your oil. Search for recommendations & change right before the track day.

 

Since there are a million discussions that all quickly deteriorate in quality, can you just tell us what you've found to work well at the track to minimize these fluctuations?

Thanks, S.

 

Phil do you have a X51 oil pan and were the 2 bar readings on both left and right hand turns?....

As for oils (God help me), I race on 15-50. I know cups were recommended to run 0-40, but most racers I know go thicker.....