Howdy,

I've done one track day in my base (2013) C6 and even though this was the first HPDE event I have ever done, I could do at most 1 lap before my oil temperature was going north of 280F and I had to back off and let it cool (This also begs the question as to what my transmission temperature was, but one step at a time.). Admittedly it was a rather warm day for my area (ca. 85F). Now that I have tasted HPDE, all I can think about is when I can get my next fix, but I am not comfortable taking the car back to any track until I sort out something for in the way of oil cooling (and a few other safety related modifications). I've read many threads on the topic of oil coolers but feel like I'm getting more lost. From what I can tell the stock Z06 set up can be bolted directly on to the base C6 (with a few holes drilled for the mounts of course) but provides too much cooling for street use and not enough cooling on the track. This can be resolved (partially) with a thermostat, but this comes with multiple reports of a reduction in oil pressure (seems to my untrained mind that this is more likely due the oil cooler itself and not the thermostat). Same for aftermarket systems but with the added questions of how to select the appropriate size cooler for my local temperature range without negatively impacting coolant temperatures (which was nice and steady at 195-210F during my HPDE day) and what will and will not fit on my car. And last but not least are a few reports of racers (admittedly only from C5 drivers thus far) not adding oils coolers at all but running heavier oil which at 280-300F has the viscosity as 5W-30 at 220F (and of course not ever driving their car on the street).

Any help sorting fact from fiction would be greatly appreciated.

 

So you did not get an Engine Coolant Overtemp warning before you saw such high Oil Temp?

When I tracked my '07 Base at High Plains, I got smoking brakes, overpressured tires and coolant warnings. I was not watching Oil temp, but the DIC did not show a warning for it. And I ... well, I tried rather hard to wreck the thing. Each session out on the track was three or four laps, 2.55 miles each lap with lots of hills, over 1 g in turns and 120 mph on the longest straight. Totally stock 3LT Base A6 Coupe using Paddles in S mode, Mobil 1 5W-30 and plus 1 quart. (Well, a previous owner did install Z51 Rotors all around.)

 

If you're going to go through the trouble of installing an oil cooler, i recommend the Improved Racing kit. It's twice as thick as the z06 unit and has a thermostat. If you're serious about tracking your car, you'll soon out grow the z06 cooler.

 

I would go DeWitts radiator with the internal oil cooler. You can then purchase a set of oil lines that install in the same place as the lines for the Z06 oil cooler but connect to the DeWitts radiator IOC. It won't over cool the oil and you will have twice the cooling capacity as the stock radiator. Add a set of ProSpeed fans with shroud and you will have tons of airflow.

 

Sounds like you really are going to take the tracking thing to the next level. In that case I would say get the dewitts and also get a very large bar/ plate cooler and mount in good air flow. In your case probably in front of rad. In addition Keeping under hood temps down will benefit the cars longevity. Plenty of threads to search.

 

I went with DeWitts with the built-in EOC/TOC and it isn't enough for a 20 minute session. The transmission warms up a lot too, especially with the A-6. Since the transmission is a direct bolt on to the differential, a Differential cooler will help keep the transmission cooler, but really an external transmission cooler is what is needed. The A-6's are fun at the track, the rev matching works great, if the transmission hasn't been tuned, You'll have trouble upshifting if you wait too long unless you have a 2012 or later which is when GM made a change to the transmission control module. You could probably do the same with a good tune. In an ideal world, you would want EOC/TOC's to not hinder the warm up process but have lots of capacity for the track and I don't know if you can keep a differential too cool. The only ideas I can offer are external EOC/TOC's plumbed through the radiator which would help take heat off the radiator and yet help keep the engine oil and transmission oil cooler. The Diff is a challenge because there is very little room and there is no temp sensor to monitor. Some people have used kits that fit inside a fender using the rear brake ducts (which you really don't need anyway) to help direct air flow through a very small radiator to help cool the oil and that also means adding a pump to the differential. Some used electric, some mechanical like on the Z-06.

 

After adding and having a VERY hot first time on track, I installed the ZR1 oil/water intercooler system. Multiple benefits. The water always heats up faster than the oil, the intercooler forces the oil to heat up faster, to get you up to operating temp. And then the water temp leashes the oil temps, keeping them within about 20 degrees all the time. I've tracked this a few times this way, in Texas, and the temps don't get out of control.

On my base 2009 vert, I had LG do the work, adding a boss to the oil pan to bolt it to, swap in the ZR1 headers and cats to clear the intercooler, and add a fitting to the left side of the radiator. Oh, and its a C&R radiator, serious race piece. And plug the spaces around the radiator to force as much air as possible through the radiator. The car simply doesn't care where I am or what I am doing or what the outside temps are, the oil and water temps stay under control. The ZR1 system is a neat concept. The parts can be found as take-offs on occasion, and LG has done these before. They did great work on mine.

Oh, and some kind of louvered hood to dump heat would be good. The more louvers the better. I use the ACP Race Hood, has about 2.5X the flow area of the C7 ZO6 hood. Been thinking about adding that C7 ZO6 vent to a base hood I have in the closet. Really.

 

Are you talking about the ZR1 oil cooler/heat exchanger or the supercharger intercooler or both, and the ZR1 exhaust system? Would long tube headers have worked with the heat exchanger? What transmission do you have? I have an A-6 in mine and coming up with spaces to mount coolers without carving up body and grill work is a challenge. By using the ZR1 cooler(s), there may be enough room in front of the radiator to install a second transmission oil cooler. The A-6 equipped cars don't have mounts on the oil pans to install the ZR-1 heat exchanger.

Generally speaking, these are superb cars but severely lack cooling capacity for any sort of track events outside of autocross. What is disappointing is it would have been relatively inexpensive to have mounting points available for easy add on coolers and it sounds like the C-7's are no different.

 

I went with a Z07 radiator and a NCC 2007 Z06 oil cooler with a factory 2006 Z06 lines. My car is a 2006 Z51, but when I built the diff, I installed the European Z51 side cover that let me use the Z06 diff pump and cooler.

 

My car is the base with manual transmission - should have clarified that in my original post.

Will the DeWitts radiator/EOC offer enough cooling for the engine oil if it isn't also trying to cool transmission fluid? A similar designed LG unit advertises 20 degree cooler oil temperatures which doesn't seem like enough based on the oil temperatures I was seeing (~280F). Is this why (if I am understanding what is being said here) to go with the DeWitts radiator/EOC AND and additional stand-alone oil cooler? (Any help on the appropriate part # for the DeWitts unit with the EOC but no TOC would be greatly appreciated.)

Will definitely continue to look into ways to extract heat out of the engine bay and increase air flow. I must admit, I do have some fears that changes that appear to be beneficial for cooling may actually be reducing cooling efficiency by changing the air flow in a way contrary to how the cooling systems were originally engineered. Perhaps I am just trying to justify not cutting up the hood :-).

Thanks for all the help!

 

https://www.dewitts.com/collections/...ts/c6-corvette

 

I retired, the second time, from an oil company and if you run to high a viscosity oil, it will drive your temps up. Are you using 5W30 per the owners manual? Knew a fellow with a Z06 that starting use 10W50 and drove his temps way up, went back to 5W30 and it solved 50% of his oil temp issues.Just something else to look at.

 

Nothing but 5W30 in my car since I took possession of it.

 

Has anyone tried 0-40 from M-1? I started running it when my car moved to Arizona (I'm still in Washington trying to retire). Street seems fine but haven't had a chance for a track day. The Oip pressure dropped a bit when I changed radiators to a DeWitts running 5w-30 and increased a bit with 0w-40.

 

Sorry I didn't respond sooner. I'm using the ZR1 oil/water heat exchanger, not the one for the supercharger. You need the ZR1 exhaust manifolds, or headers meant for a ZR1, to clear the unit, as it sits near the oil pan on the left side. I run an A6

 

Did you replace the oil pan? Mine does not have the mount points for the heat exchanger mount, I also have the A-6 but need something more than the EOC on my DeWitts. For that matter, the TOC isn't enough either. I think cooling help is available by cooling the differential oil, there are lots from Chevy for the C5R T-1, and DRM has a kit. I also like LG which uses a mechanical pump.

 

Nobody else is questioning why his oil gets THAT hot in just 1 lap? I've never done a track day but that seems like something is fundamentally wrong.
I get that a base car may not be sufficient for repeated 20 minute sessions, but getting that hot in 1 lap seems like there is something wrong.

Is oil pressure at reasonable levels?
do you have too much blow by? i think there's a way to do a leak down test?
compression tests are easy enough to do, might be worth doing one?
what oil temp were you at if when you begin the lap, if you get to 280F before you finish 1 lap?
why did nobody else question this, do all base C6's overheat in less than 1 lap? doesn't seem like it. something is different here.

 

The installers, LG, welded the bosses onto the pan, no worries. You DO have to add an extra inlet (outlet?) to the radiator, more welding. Neither of these is especially tricky. I've been running this system for maybe seven years, nary an issue.

The C&R radiator I have has a section for the trans, though if I was going to track it a lot I might think about getting a separate cooler somewhere under the car. Ditto for the diff.