Engine oil temp on race track

StuM5 · Apr 29, 2015

I've had the SLC on the track on 2 occasions now.
First time the LS3 engine oil temp reached 140 degrees C (284F). I Then installed an external oil cooler in the side body ducts with shroud and proper ducting to slow the air speed to allow effective cooling.
I'm running Penrite HPR 5 5w-40 oil.
On the first session on the track yesterday after 15 minutes oil temp reached 123 degrees C (253F). We had to leave track due to a CV boot coming loose and spraying grease everywhere. I couldn't repair and thus no more track time. Water temp was perfectly fine.
What engine oil temps are others seeing on the race track with LS3 or LS7 engines?
Fran what does the green race cars oil temp sit at?
What is the recommended oil to use, on track, to keep oil temp under control?

Cheers
Stu

Jim C · Apr 30, 2015

Stu

The heavier the grade the hotter it will run.
Lots of people thing if I am thrashing it I should go heavier.

Not the case on modern engines the oil is selected by the manufacturer on bearing tolerance.
If the oil is heavier than speced it is forced into the bearing and the oil runs hotter.
I would run around the man spec but full synthetic

One of the guys in my club with one of these engines was telling me his oil temps get up around the temps you are stating in his roady if he tracks it.
I reacon its to high.

I see about 90-100c in my modular eng.
I did see 120c plus before running the cooler.

Jim

gt40fran · Apr 30, 2015

Stu, with a 500 plus hp LS engine ,we see 250f regularly using Mobil 1 with no ill effect (we have run up to 275-280 with no issue yet) . I will check on the oil weight as I don't recall from memory.
15/50 oil

I have checked with some of our engine builders and they say the temps we see are fairly common on track.

edit: that's with dry sumped engines and 3 gallon oil tank.
Edit 2 Temp change per keith

Keith1 · Apr 30, 2015

You do mean 250 degrees F don't you Fran? :worried:

gt40fran · Apr 30, 2015

Lol yes I do keith

Keith1 · Apr 30, 2015

Thank God! For a moment there I thought you had invented an engine lubricated by Pyroclastic Flow... :stunned:

gt40fran · Apr 30, 2015

Just having a dyslexic Limey moment

jac mac · Apr 30, 2015

Where in the oiling system do you have the temp sender unit mounted?
Have you tried using a lower rev limit for a period of time to see if temps are rising exponentially with rpm, a possibility here could be crank /flywheel balance as you SLC guys seem to like bolting non-factory flywheel/clutch assy's on without strip down. If your engine has piston squirters in the block this can give a high oil pan temp reading due to the heat picked up in the process, and relocating the temp gauge pickup to a point after cooler will give a lower & more useful reading, two temp gauges during initial sorting would confirm this.

gt40fran · Apr 30, 2015

Personally I use the stock oil pressure and temp sensors and locations for the very reason jac mentions

StuM5 · May 1, 2015

Thanks for the responses.
Jac the oil temp sender unit is mounted in the factory position for the LS3 in the sump/oil pan.

I’m going to install a temp sensor just after the external oil cooler. The Digidash can only read one oil temp and I’m not going to the hassle of running another gauge. I will create a connection in the existing wires coming from the sump sensor which will allow me to easily unplug the oil pan sensor and plug that connection into the new sensor installed after the cooler.
This will then tell me the temperature of the oil when it’s first returned to the block and thus clarify whether the returning oil is cool enough too safely run the engine.

A few people I’ve spoken to are running this water to oil cooler and achieving excellent results: Inline Engine Oil Coolers | PWR Performance Products

Fran are you saying Mobile 1 15/50 is the answer to the track oil question?

cheers
Stu

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jac mac · May 1, 2015

I would prefer the inline water/oil cooler over the air/oil system, as long as you have sufficient normal radiator capacity, had far too many unnecessary 'failures' in cores of the old air/oil units.

blueovalz · May 1, 2015

jac mac said:
I would prefer the inline water/oil cooler over the air/oil system, as long as you have sufficient normal radiator capacity, had far too many unnecessary 'failures' in cores of the old air/oil units.

Is FOD the reason, or was it other issues that you've seen?

turbodon · May 1, 2015

At QRP we are in our 3rd season ( 2 x 25 hr events + many more 3 & 4 hr runs) on the GM LS3 376 crate motor. We run dry sump with external fan on oil cooler. We run the GM recommended 5-30 Mobile 1. We have no oil issues.

Why would you run a higher viscosity oil? On a GM crate motor you do not.
1) Larger bearing clearances (custom race motor).
2) Increase oil pressure when oil is hot (point 1 above).
3) Alcohol motor (oil contamination) Sprint car racing 20-50 or greater.

If you have sufficient oil pressure at 280F, then your oil is thick enough.

Increasing oil viscosity greater than that just adds heat.

gt40fran · May 1, 2015

I run the oil recommended by our engine builders
Katech and Thomson automotive
If it's a crate engine run what's recommended

jac mac · May 1, 2015

blueovalz said:
Is FOD the reason, or was it other issues that you've seen?

No foreign object or inflicted damage Terry, just leaks developing between tubes and end tanks etc and not really in one area, with no definite explanation other than poor quality . By contrast the water/oil unit was/is bulletproof and has the advantage of being completely dismantled for cleaning for the outlay of a few O-rings. I have never felt comfortable about any of the touted methods of flushing crap out of the air/oil versions especially if they are high $$$ versions with turbulators built in!

StuM5 · May 4, 2015

Ok thanks again all who chimed it.
I have a GM crate engine L3/376 480hp engine.
I’m running a wet sump, external oil cooler and Morso 3quart accumulator.

So, after a little more homework I will hold off going to the trouble of adding an engine oil temp sensor mounted after the oil cooler. As there is an easier test...

This is what I understand I should do:
1. After returning from a track session check the oil colour. If the oil is NOT black then the oil, and therefore the engine, are not being harmed at the oil temps I’m seeing. Is that correct?

Further queries:
2. Don, are you directing your oil viscosity comment at Fran or me? I’m confused. I think
what you are saying is that I should run 5W-30 Mobile 1 because it will run cooler than my
current 5w-40 oil?
3. Don, what engine oil temp does the race car normally run at?
4. What is a ‘safe’ oil pressure at this temp?
5. Don, Is there much difference in oil temp if you don’t have the fan on the
external cooler running?
6. Don, you mention an oil is thick enough to run at 280F if oil pressure is
sufficient. If I see oil temp between 250F and 260F using 5w-40 oil at
what point would oil pressure be considered to be unsafe?
Digidash currently has the oil pressure warning alarm set to go off if it
drops below 30psi.
Next time at the track when I get the oil up to 250F-260F I want to be
able to set the oil pressure warning to go off if oil pressure falls below the
‘unsafe value’ for that temp range. Just need to know what that value is?
I think this is an easier way of
checking this issue with the tools I have rather then other means.

Cheers
Stu

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turbodon · May 5, 2015

Stu

(2) Oil comment is directed to all. Yes 5W-30W.

(3) Laguna Seca in afternoon (80 F day time temp). 245 to 247 F oil.
Thunderhill afternoon (100 F day time temp). 270 F oil.
Infineon Raceway ( 90 F day time temp). 265 F oil.

(4) Above 30 at idle when oil is hot.

(5) Yes

(6) # 4 above. 30 psi is a good warning. You could creep it up by 2 psi until it becomes an annoyance by setting off warning every time idle dips a bit. then set it 2 psi lower.

Stu

You can run 5w-40. It won't hurt a thing. The only reason I posted on this subject is because people hear "Oh blah blah is running 20W-50 in his race car" So they go buy 20W-50 and put it in their Crate motor because they are running at the track.

As Fran stated run the manufacture (engine builder) of engine recommended oil weight.

Example:
I have a Ford 351W stroked to 410. It has a high volume oil pump.
With 10W-30 the Hot oil pressure at idle is 45 psi at cruze (2100 rpm) is 65 psi.

I dropped the oil to 5W-30. Hot idle is 35 psi cruze (2100 rpm) is 55 psi.

Howard Jones · May 5, 2015

Question for all. I have a engine coolant to engine oil intercooler like Jac recommends. (SBC @500HPish with a wet sump Cannon 8Qt RR pan). I was thinking that the oil will run closer to the water temp using one of these type oil coolers. What does the group know/think?

Don, what water temps did you see in the three examples you cite. Yours are the first real data points I've seen. Thank you so much for them!

turbodon · May 5, 2015

Howard

We run an electric water pump and no thermostat.

The Engine water temps.

GM's ideal temp for LS is 220 F with EFI.

212 - 225 F Thunderhill (during 25 hr have to block of radiator to get operating temp)

195 - 200 F Laguna

196 - 200 F Infinion

Yes the heat exchanger will run closer to the water temp on exit of heat exchanger. It better or something is wrong.

You still have the same heat entering.

It all depends on where it is measured.

Example:

Oil temp off of bearing will be around 300 F (maybe more). By the time it gets off block and to a Pan temp sender maybe 290. By the time it gets to a dry sump tank maybe 280 - 285. After heat exchanger (water) water temp of engine. After external radiator type cooler ? never measured.

With high HP engine and heat exchanger must make sure coolant system will handle extra heat. Radiator surface area.

Hope this all makes sense.

Howard Jones · May 5, 2015

Since the oil being "applied" to the bearings and elsewhere is the "cooled" oil coming from the cooler wouldn't be what I want to know the temp of? Cooler exit point.

Right now the sender is in a bung in the pan. Maybe once I have some data I'll move it to the cold side of the cooler. But what you are saying is oil temps in the 280-290F range is OK however temp are higher or lower depending on how close to the heat source (bearings etc.) it is, Then it is cooled and returned to the heat source again.

I've had good luck running old school V8s at 200F maybe a bit more on track without problems so I was going for that. Is returning 200F oil to the engine OK. what do we/you think?

We'll see what the OEM radiator can handle and go from there. I'm only running 25 min sessions so I hope I'll be OK

Makes sense, Thanks again.

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