billy mild

I did my first ever track night in my 2003 Z06. The car is obviously way above my driver level, but gives me plenty of room to grow. I have heard the LSx engines run hot and don't use oil coolers from the factory. After my first run the car was running around the 240F water temp and 300F oil temp. My last Corvette was a C4ZR-1. It never ran above 220F Water and 240F oil temp. That car had a huge oil cooler from the factory along with a tune to turn the fans on at a lower temp. What can I do to make my car run a little cooler.

I have two theories on how to keep the C5Z06 cool:

1. Run an oil cooler with a thermostat(for the street driving I do once in a while) that will lower the oil temps significantly which will also in turn make the engine overall run cooler
2. Run a upgraded radiator. Coolant temp will be lower therefore oil temps will be lower as well.
3. Run an oil cooler and change the tune to turn on the fans sooner.

Thoughts?

fuggles

I was in a similar position. I would regularly see 290+ oil temps [although I never saw 240 coolant temps. maybe you have a coolant issue] on the tracks I run. It was getting annoying having to short shift and run cool down laps. So I was mulling getting a standalone oil cooler with tstat. Then I spoke to Randy at DRM about his kit. He is not a fan of putting a tstat in the oil cooler line. Concerns about restricting the flow etc. After a lengthy conversation I ended up with a new radiator with integrated oil cooler. Best of all worlds. Improved engine cooling, improved oil cooling, doesn't restrict oil flow and no worries about low oil temp on the street. Of course I spent a lot more than I had planned. I haven't tested on the track yet, so we'll see if I got all I wanted.

billy mild

What temps were you seeing for coolant? I spoke with a few other C5 guys and they were seeing the same. I did not short shift or run cooldown laps. Maybe I should have.

My coolant is fresh. It has been completely drained and refilled and bled.

Bill Dearborn

Run an engine oil cooler, transmission cooler and a diff cooler. You need all 3 to be reliable. Don't bother changing the fans or the thermostat. The fans don't run above 35 mph and the temps you are seeing are already way above the 186 deg stock thermostat.

I ran the DRM Ron Davis Racing Radiator with a built in engine oil cooler and an external oil filter on my two C5s. Coolant temps ran around 200 and oil temps around 230. Of course with the extra quart of oil GM recommends for tracking the cars that brought the total oil capacity up to 9 quarts. I also ran the GMPP T1 trans cooler which also cooled the diff. You can do just as well by running separate trans and diff coolers (they are needed)

Another thing that can help the car in another area is to run a much larger PS cooler than comes stock on the Z51 and Z06 models. I knew a racer that ran a cooler that was the size of one of those aftermarket hang on automatic transmission coolers. That kept the PS Fluid much cooler and preserved his PS pump and rack.

Bill

REVHARD

The C5 is a great car but most need to remember it's 20 years old. I would pull the radiator shroud and clean out all the grass, leaves and gunk from the radiator. Use an air chuck to blow out the dust and dirt from the fins too. People would be shocked how much gets stuck in there after a year, let alone 20.

But as Bill stated, the C5 is a reliable track car when equipped with the bigger radiator, oil cooler, trans and diff coolers.

billy mild

I already cleaned out my radiator a few weeks ago to prep for this track event.

fuggles

I never saw above 230F coolant temps.

I am paranoid about 290F oil temps. In my previous track car I used 20w-50 oil so I felt better about high temps. In the corvette I read much about oil and LSx motors so I use 10w-40. Makes me more concerned about high temps. Oil cooler should take care of it. Back to WOT til the red line.

Fulton 1

I’m just an HPDE guy without aero and on 200TW street tires and not a racer, but it sounds like your needs are similar to mine so I thought I’d put in my two cents.

First thing I did after purchasing my C5Z back in 2013 before tracking it was to install a DRM trans/diff cooler kit and a DRM Ron Davis radiator with the integral EOC. Note that I decided NOT to do the shroud cutouts and trimming that DRM recommended in the instructions for radiator install.

I mainly visit a couple of local tracks to me and we drive to and from (up to a 260 mile round trip) so a balanced (i.e. street friendly) car was important to me. I’m in the Seattle area where stop and go traffic is inevitable and ambient temps rarely climb much above 90F, but you can get lots of humidity on those partly cloudy, summer days, which does seem to impact my temps.

During the five years that I’ve been running this setup I’ve been on track on pretty hot and humid days by our standards and after pushing pretty hard for a 20-minute session I might see oil temps climb to 270-271F range. On cooler summer days (say, low 80s) I’m in the 260F range usually after a hard 20-minute session.

FWIW, I’m running stock fans and the stock 186F thermostat, but have adjusted my fan temps in the tune as follows:
Fan1 ON: 201F
Fan1 OFF: 191F
Fan2 ON: 211F
Fan2 OFF: 202F

I’ve found this to be a very happy and reliable setup both on track and on the street and annual oil analysis results seem to back that up.

Hopefully this is a useful data point.

billy mild

If I went with just an upgraded radiator like a ECP aluminun dual core one will that make an impact to oil temps at all? They don't run a integrated oil cooler.

carcrazysammy

A few weeks ago I tracked my C5 Zo6 in 105F weather. The car is stock except for a DRM track oil cooler. Even with the oil cooler I got the oil to 285f. The water hovered near the red (not sure what the exact temp was) but never went over. The oil cooler makes a huge difference. The only down side is in temps at 60F on the freeway the oil won't get above 155F.

The transmission overheated and puked fluid when cooling off in the pits after a hard run. I short shifted the rest of the day and never got an over temp alert after.

Next modifications are to get a transmission and rear diff cooler.

bj1888

Where do you live? I'm in Florida, and needed both an EOC and bigger radiator to keep temps down, but it's pretty damn hot here. If you regularly drive in cold weather, get a thermostat for the EOC.

For 30 minute HPDE sessions, trans and diff coolers aren't absolutely necessary. It took me about 45-50 minutes of continuous lapping to trigger a trans temp warning.

Mrsideways

So as a Reference. I just took mine to the 1st track night in america event (my first time tracking it since owning it, I tracked it some as the instructor for the previous owner). I would do 1 or 2 hot laps then a cool down to look for open traffic to go for another hot lap. I saw 220f Coolant and 270f Oil temps. thats with an aluminum rad and the oil cooler in the end tank of the rad. Now before the previous owner put those in I ran it on sebring and on my 1st hot lap I saw 230f water and 303 oil temp. So they make a difference. HOWEVER sebring was run in June during the day and TNIA was at dusk and it had rained shortly before so it wasn't blisteringly hot out.

Video link to show how I was driving.

Bill Dearborn

The RD unit is a very good unit with the following features for the C5: 2 rows of 1" wide tubes and the Engine Oil Cooler which is built into the passenger side tank which runs pretty cool on most days. My RD radiator cooled the car down considerably. I don't know about the ECP products but the RD is the real deal.

Bill

kmagvette

Mr. Mild, assuming that all your fluids are moving around like they should, you just got the car, and you hit 300* (at night) during your first event, then you need more than an Oil Integrated Radiator. I started out with one of those myself, it worked for a while, then I got better and the Oil Integrated (Dewits) could not keep things cool enough.

I called Randy at DRM and he hooked me up with the Ron Davis, water only, radiator and the Setrab 625 (I think) dedicated oil cooler...no thermostats or anything else to get in the way. When installing the radiator, I cut out all the extra material in the fan shroud per the installation instructions. Since then, on Pirelli Slicks, the highest oil temp seen was 245 deg. Water temp (160 stat) is high 190's. The LS6 was putting out 450 HP to the rear wheels. If I drive on the street, I just put Cling Wrap (Press-n-seal) on the oil cooler. I rarely drive on the street other than to be sure things are solid for the next track event.

You are probably going to end up putting coolers on the diff (first) and tranny. A larger power steering cooler is also a good idea. Mount it next to the Setrab. You almost double the volume of the power steering system and your fluid will only get warm.

Hope that helps. The C5Z is an awesome track car. Welcome to the club.

Spaggs

Randy at DRM set me up with a Setrab 925 stand alone oil cooler. It brought my oil temps from the 300s to 260 at Road Atlanta during a very hot day. Randy is great guy to work with. The 925 is not part of their catalog, so you have to ask Randy to help you out.

Good luck to you.

Spaggs

kmagvette

Spaggs, thanks for the 925 info. I am doing an LS3 build right now (582 crank HP during dyno break-in) and want some additional cooling. Randy stuff always bolts up easily, will give him yet another call.

YEGC5Z06

Did you have to do any modification to the oil lines? I have a DRM oil cooler kit with Setrab 619 hooked up to my LS3 418, and my oil temp can still reach 300F on the track. A 925 would likely cool things down a little bit more.

J.R.

Never had an overheating problem following the above recommendations by Bill. This is at 100 degrees and 4300 ft. elevation. A Turn One PS pump helps solve those PS issues.

Ludicrous_Speed

*Edit* wrong thread

Bill Dearborn

You are talking about a C7 Z06 not the C5 referenced here. The C7 Z06 over heating comes from the lack of cooling capacity in the cooling system for the power level being generated. GM resolved this on the M7 cars by adding a secondary radiator in the 2017 and newer models. That radiator dropped engine coolant and engine oil temps just about 14 degrees. The radiator can be added to 2015/2016 M7 cars.

They also changed the intercooler in 2017 by tilting the bricks inside the supercharger. The LT engines have higher combustion chamber temperatures in cylinders 7 and 8. The tilted bricks reduced the charge air intake temps for those two cylinders which reduced the chance of high rpm wide open throttle misfires in those two cylinders. If you look at the bottom of the supercharger you can see that tilting the bricks improved the air flow into those two intake ports. The Intake port for cylinder 8 didn't have any portion of the intercooler brick above it so air had to flow through the intercooler make a sharp turn to travel through the log manifold a few inches and then make another sharp turn into the port. With the tilted bricks the air coming out of the bricks was aimed toward the port which I suspect cut down on turbulence.

View into cylinder 8 manifold port.

Number 7 wasn't as bad as the brick ended right at the edge of the port but the air still had to turn to some degree after exiting the brick.

View into cylinder 7 manifold port. You can just see the end of the intercooler brick on the left side of the port.

For comparison this is what it looks like looking into cylinder 1 port or any of the other 5 remaining ports.


Reducing the combustion chamber temps for two cylinders probably lowered engine coolant/oil temps as well but I doubt it was nowhere near as much as adding the radiator.

Bill