Several years ago, I learned quickly how hot a car can get running WOT on an oval track / infield course. My 04 C5 A4 transmission temp crossed 300 F before it went into “crawl home mode”. So I added a 14K BTU B&M transmission cooler and I never saw another overheat, even on a 98 degree day.

I bought my 09 C6 A6 with the Z51 package thinking GM had recognized and fixed all my overheat problems with the added coolers. I was totally surprised when I couldn’t find the coolers and the LS3 in fact ran slightly hotter than the LS1 on the street.

I run track days at TMS in Fort Worth and the Big Bend Open Road Race. Both of these events are sustained runs at greater than 130 mph for greater than 30 minutes. Typically outside air is 80 F to 95 F. The car gets hot!

After a lot of help from forum posts and my C5 experience, I added a B&M 14 K BTU tranny cooler and a C6 Z06 engine oil cooler. 1.2 lateral G turns at 70+ mph are part of track days, so I spent a lot of time securing the tranny cooler.

I added a bottom screen and a front input screen made from Home Depot open mesh. The C5 twice sucked a plastic bag and was always vacuuming up leaves. The screen on the C5 stopped that. The mesh I used on the C6 is open enough to not limit air flow. I did not want track projectiles taking out the coolers.

It’s pretty tight with the tranny cooler and the oil cooler in front of the AC condenser. I kept about a 1 inch gap between them. I did not want to create a cavity for small trash to accumulate or reduce the cooling air to the radiator.

How well does it work? I haven’t had a track opportunity yet. It’s about 103 F in Dallas now. I have taken it out for several 15 to 30 mile highway drives at 65 to 75 mph. I tried it with the tranny cooler only installed, the tranny cooler and the oil cooler and both coolers with the screens installed.

I logged the data from similar runs before the mods and compared the results and the results from my C5.

If I enter the highway from a cold start, with external air at 102 F and the AC at max, the coolant temperature varies from 199 to 203 F, the transmission sits at 182 F and the oil temperature is 203 F. If I then slow down and add some start stop city driving, the coolant reaches 208 F, the transmission 194 F and the oil 205 F. The screens did not change the temperature readings.

WOT on a track or in a race is more stressful than this test. But at least I always have an air flow. The highway tests show the cooler additions cause a 0-3 degree rise in engine coolant temperature, and about a 23 degree drop in oil and transmission temperature. The C5 transmission temp never crossed 205 after I added the cooler.
Most of the Did Not Finishes I see at the track and in the road races come from overheats. I am betting these coolers will get me to the finish line and keep me from sitting beside the road.

 

GM did look at the problem, but since thats want happens with a big hyd. pump, they did the best they could for the money! they figured if a person was going to buy the car and track it alot or race it then they would buy a manual, see any race cars with an auto?

 

Yeah, most of the quickest C6's on the drag racing list are automatic.

 

How about a photo of the install.

Also any others that have alternate trans cooler installs, photos and comments please.

 

Are you also running a cooler thermostat?

 

Let me know how it works on the track - I have an LS3 M6 , and I did get the factory oil cooler , and the car still goes over 260 oil temp after 25-30 minutes on the road course .....

 

Thermostat and tune are stock.
I did a lot of tuning on my C5.
I had to undo it every time I had a warranty issue.
So I am leaving that alone.

I have a roval date Sept 11 at Texas Motor Speedway.

1.5 mile oval plus 1 mile infield course.
Top is about 140 crossing the finish line.

There are three SPCA groups running plus a street car group.
So we will run for thirty minutes every two hours.
It was 98 F when I finished last year.

I cycle through the DIC on the cool down lap and talk to my camcorder to catch the readings.

The transmission cooler made a 30 deg difference on my C5. Oil wasn't that much of a problem. The LS3 runs hotter on all the comparison runs I have made up til now, so I am counting on the cooler to keep the oil temp below 250 F.

BTW the mpg is about 7.6 for this roval.

 

Try pulling the thermostat out for one of your track sessions. With the stock thermo, your starting coolant temp is going to be 190+, and it will go up from there. The hotter the radiator is, the less cooling you will see for the oil cooler.

Every little bit helps.

 

You have the Z51 "waffle" sized cooler. You can upgrade to the full length Z06 Engine Oil Cooler that works much better. The your existing oil lines will plug right into the Z06 cooler.

 

Hi,

A week ago I ran my 08 Z51 6spd manual in an HPDE in 100f+ weather all day long.

I cant tell for the trans speed since I got a manual, but concerning engine oil I've been hovering between 280f at which point I started turning the AC off and stabilized around 290.

Modern synthetic engine oils like the oem Mobil 1 can take quite a beating , in fact I'm pretty much sure there is a video from Mobil on youtube called "journey through an engine", or something like that, that speaks about corvettes and states that the oil can keep it's stuff together up to 400f. There is a good chance you will reach the temperature limit of other parts of the car before you reach your oil's limit.

In addition, as a last firewall, Engine over temp / or engine protection message and chimes will ring before your oil gets hot, but not before it reaches 320f, and wont turn off until the issue is resolved.

so provided your oil is young and "fresh" enough, 260+ is still ok