mlongo99

For those of you that have done track events in your C6, what kind of oil temps did you see? I took the C6 on my favorite twisty mountain road on friday for the first time and I was pushing it pretty hard. The car said outside temp was 92. After a while the oil temp got up to 260. I backed off and after staying at 260 for a while it started dropping. It went down to 230 and I got on it again and temp started rising again. After 30 miles and over 4000ft elevation climb, I turned around and headed down the mountain. Oil started at 220, but again hit 260 so I backed off for a while. I think coolant stayed 220-230 the whole time, and I've got Z51. Is this too hot? Should I be concerned?

I'm planning on going to Willow Springs in November, and possibly September. If it's a warm day will I have to worry about this? What can I do to help?

Also, my tires were 30psi cold and once hot went to 37-38. Any recomendations on hot tire pressures for the track?

For those of you that are wondering, I had a great time and got a good feel for the car. I'm very impressed at how well it handles, the brakes are great and were completely fade free.

LS WON

neko_cat

I've had my z51 out to willow springs streets but I didn't pay close attention to oil temps. I was watching oil pressure for any drop. I had oil pressure set in the hud and tire pressure on the DIC when I wasn't watching fuel usage.

The car was fantastic, very balanced and nice power. I had a blast.

Unfortunately I don't have any information on oil temps or pressures. The pressure will rise LOTS and you will need to keep bleeding down till your happy as you go. You can chalk the side of the tire to see if the tire is rolling over.

I can't remember what I started the tires at sorry.

I have video that I still haven't looked at.

Let me know when your going and who with. Maybe I'll join you guys. I'm itching for track time. Might need new tires.

-mikey

TRR

At Motorsport Ranch last month, mine got up to 245, but it had been raining and was not very hot. I don't think you have anything to worry about till it gets aroung 280 or so.


TRR

MitchAlsup

260 is a tollerable temperature at high loads, 265 becomes iffy, 280 is trouble territory (for more than a minute or so). I guess I an surprised that the Z51 oil cooler did nto keep the temps lower (like 250) since it was only 92 outside and we race down here in Texas with ambients of 103+.

Another variable is the oil itself: how many miles on it? what brand? weight? I try never to go to the track with more than 1000 miles on my oil and change it after a weekend of lapping. You might want to look for an oil that has an HTHS number above 3.2 and you can find oils with HTHS numbers of 3.6 and still remain in the 5W-30 weight classification. An oil that is too thick can also increase on-track temperatures (any xW-50s and several thick xW-40s). As long as you are researching oil, you might want to look for an oil with a normal operating viscocity of 12; whereas M1 has a normal operating viscocity of (old formulation 10.3; new formulation 11.2).

You should be adjusting tire pressure after a hot lapping session to about 40 PSI as a general rule. Your driving style and that track my want a little less or a tad more, and you can and should use tire pressure to balance the oversteer/underteer relationship that you want on the track.

Once you start driving on the track, you will make more progress, faster, by using a probe tipped pyrometer to measure tire tread temperatures and adjusting the alignments of the suspension to fit that track and your driving style. A fabulously useful device that can pay for itself in longer tire wear in agressive conditions.

ein Tier

I've been to the track, but I wasn't really watching the oil temperatures other than to make sure they weren't overly high. I don't remember what the max was, but I don't remember it moving appreciably from normal driving. This was a hot day at TWS as well.

I am going back in mid-September. I'll be sure to watch then. And about the tire pressures, they do go sky high once you really start driving hard. I saw a good 15 psi jump, and it could have been more, as I was constantly bleeding off excess.

drrichie

The Hottest oil temps I have seen is 245 on my own and two other Z51's in competion. As for air pressure I carry a very small compressor and a good gage. If I am out and about for hours at a time on manouvers - hot sunny day on hot blacktop it's easy to see expansion 7 to 9 pounds - even more. I let the pressure down to where it should be and adjust it when things cool down. 30 lbs is 30 lbs, doesn't matter if its in the winter or summer, racing around or not.

Rich

mlongo99

Thanks for the replies guys. Great info!

AU N EGL

I agree with Mitch. 250-255 is normal, 260 is OK but the "I need to watch " if OVER 260 then time to short shift and cool down. Yes the Mobil 1 or other synthic oil can take higher temps but the internal engine compants can not take those temps. Hense the oil cooler.

Is the C6 Z51 oil cooler sufficent?? it depends on your driving style. For most ppl yes it is. For hard core ppl running R compounds, then an additonal oil cooler may be needed.

Tire pressuer ON or just after you come off a hot lap should be about 38-40 psi HOT. the air in the tire heats up about 6psi. So starting 30-32 cold means 36-38 HOT. adjusted per driving style and the number of hard corners.

On some tracks I put 1/2 psi more in the front right OR left tire depenind on the number of HARD turns in the oppoist direction. If there are 2 or more very hard turns to the right on the track I will put 1/2 psi more in the front left tire. Yes after a while you do notice 1/2 pis or 1 psi difference in your tires.

Good luck

MitchAlsup

I see 6 PSI is with nitrogen filled tires, and see 8 with regular air filled tires due to the water vapor inside.

If you have a tire temperature guage (probe tipped pyrometer) you are shooting at 190dF to 210dF for the inside edge of all 4 tires. Anything hotter and the rear end gets that greasy feeling.

TooManyIDs

From what I've seen, the Z51 oil cooler could do a bit more. My temps run around 280+ @ MSR.

That's better than the 305 I saw in the Z06, before adding an oil cooler. Even with a DRM cooler & Mocal engine oil thermostat, oil temps still ran around 270 in the Z06.

So much for the "engine limit" of 260. Where did that number come from? What temps are you running with your coolers?

connor

I have hit 260 with spirtied driving down country roads for long periods, it was during a ZO6 fest WART drive (Wild *** Road Tour) through Kentucky back roads. I had no problems with brake fade either even after shaving of 60-80 or so on the many bends. During my normal driving I range around 230 to 240. I get similar temps with my ZO6 but it does not have an oil cooler so I am not shure how effective this oil cooler is. OH and mine is a Z51 also and yes it will keep up with stock ZO6's.

yellow01

260?! Pshaw! That's nothin'!!!

I was hitting 290++ and it was only 90* out. Promptly went and purchased an oil cooler and am awaiting the next track day for performance assessment.

clem zahrobsky

mobil 1 says the oil is good till 400 degrees because even dino oil is good to 270 degrees without break down

AU N EGL

Yes the oil can take those temps but the internal engine componants can not or not for very long.

Oil temps above 260* is the magic number to slow down and cool off.

Highest I ever saw was 360* then I learned about oil coolers and promptly put one on along with an accu- sump and transmission cooler.

MitchAlsup

Just because the oil is not self destructing, does not mean that the operating viscocity is sufficient to keep metal to metal contact from happening inside the engine. The viscocity of oil is temperature dependent, the higher the temperature the thinner the oil. Yet the oil viscocity must stay above a certain point to perform as a lubricant.

The most representative number in the oil MSDS sheets is the HTHS number. This number is measured at 150dC (285dF). For track purposes, I would be looking for an HTHS nuber above 3.6. I might note that M1 does not meet this number, while there are 5W-30 and 10W-30 oils that do. Because of the HTHS numbers, we recommend keeping the LSx engines below 260dF, with thicker oils (HTHS > 3.6 :: a little thicker not a lot) you can go to 285dF witout taking serious risks with your engine. Anything hotter than this is asking for trouble.

And before you start trying out 20W-50 oils for the track, oil this hot points to needing a oil cooler (or a bigger on or in a better duct) than thicker oils.

clem zahrobsky

i bet GM has a temp sensor in the corvette that shuts down or kills engine power when the oil temp get to high just like the "limp home" feature if you loose the water. we have run race cars with oil temp over 300 degrees with no failures using mobil 1. mobil 1 used to run a TV ad with jeremy mayfield talking how they ran their NASCAR engine at 340 degrees for the race with no problem.

jmess

Test results from an oil mfg on the NOACK test for oil evaporation due to heat. As oil evaporates it becomes thicker and harder to pump (oil pressure drops).




Wondering what temp they test at? Here is the test device they use. 250C = 482F.

http://www.petrolab.com/pages/petrol...e=details#view

AU N EGL

You are absoulty right. But the average person does not rebuild their engine after each or after two races, nor do they drive at WOT for several hundred miles each weekend.

If I had a big $$ sponsor I would run the heck out of my car all the time on the track. Well I do have one sponsor. "OUT-A-MY-POCKET" which paid for my oil cooler, accusump and transmission cooler.

jster171

I just completed a track day at Road Atlanta, which is a very fast track. My Z51 MN6 had 1100 miles on it at the time. After 2-3 FAST laps, pushing the car past 6000RPM at every shift, I saw oil temps as high as 305 and water temps as high as 225. I did notice that the oil cool down VERY fast, I could take ONE lap fairly conservative, shifting at around 5200RPM and get the oil temp back down to 260. So, it seemed like RPM was the biggest heat generator, which makes sense to me.