I installed an APR wing and balanced the front downforce with a duraflex lip splitter (the one with the center vent in the right place) and canards. For the first time I'm seeing water temps in the 250 range and oil up to 297. The Glen is hard on engines with a lot of climb and constant redlines, but I've never seen close to those numbers elsewhere so I have to assume it's the splitter breaking the normal airflow.

Is there a trackside fix that I can apply that doesn't include removing the splitter and unbalancing the car? Willing to cut the bumper cover, I have another. Trying to break into the teens on street tires and having to short shift to keep the temps down. Help save my track event!

 

arnt those cars ''bottom breathers''?
if so are you cutting off air intakes for the rad/oil coolers?

 

They are, but the splitter does not extend very far back, so doesn't block the upward airflow. I'm not an airflow expert but I expect it's still doing something to limit the effectiveness.

 

I don't know about a trackside fix but when I was seeing oil temps of 305 or so, I installed an oil cooler/water radiator and never went above 260 afterwards. I used to drive the glen a lot

 

I agree I need an oil cooler. I figured the accusump may provide some cooling but it looks like I'll need more. Talked to another guy here with a c5z that has a similar splitter and he's having cooling problems as well. But he removed the air dam under the bumper and I know that will be an issue. I figured out a way to plan my shifting to avoid high revs and I'll be fine. Just won't break into the teens today!

 

I've read some people can get there hands down through the headlights to the fog light surrounds to remove them for more airflow. Not sure if you have tools.

 

If you did not have coolant 250, oil 297 before the splitter, at the same track, the splitter is interfering with air flow. Stock air dams in place, good shape?

 

Thanks for the replies. This is the first time at the Glen, and first time with the aero, so I have nothing to compare. I had hoped to get in a test day but that didn't work. I do have the fog lights and baffles removed (this car is far from stock) and that air gets to the engine air intake but not to the radiator. I'm afraid to mess with the radiator shroud in fear that it will reduce the cold intake from the bottom feed.

I will try to see what I can do to widen the area above the splitter to allow more air in at speed. I have an event on Friday (busy week) where I can test the cooling on a more "normal" conditions where I'm not at WOT for most of the track.

 

At speed above 35 mph, C5 cooling is based upon the higher pressure of air just before the air dams which force air up through the shroud, through the condenser and radiator into the lower pressure of the engine compartment. If air is allowed to bypass the shroud and go directly into the engine compartment without first going through the condenser and radiator, this can reduce the amount of heat removed by the radiator, potentially cause increased coolant temperatures and later, higher oil temperatures. Places where air can bypass are the fog light recesses as well as the front license plate, if the plastic closures at the rear of them are removed and air is allowed directly into the engine compartment.

There are a number of posts where forum members have experienced higher than normal coolant temperatures at speed by simply removing one or more air dams.

 

Thanks jim993, what you say makes sense, but the fog air dams have been removed for years (and isn't the Z06 designed this way?), and I've also had venting in the hood that further releases the pressure (and heat). No cooling issues until I added the splitter, but also not tested yet on a less demanding track. I know as a driver I'm not yet a match for the Glen, maybe the car isn't either. Appreciate all the input.

 

Our cars do not compare, mine is a base A4 Coupe, no engine mods.

I have noticed that Laguna Seca heats the drivetrain much more than Buttonwillow. Thinking about that, the reason seems to be that I am able to be at full throttle over more of the track at Laguna Seca, plus Laguna Seca has two significant uphill full throttle runs.

Over the last eight years, on track cooling issues on my car have been more focused on the transmission, although all the drive train components are interrelated in heat transfer. To keep my car cool I have done the following, completed by about late 2014:

-B&M finned aluminum transmission pan, 2 quarts more capacity
-DeWitts double thickness aluminum radiator with transmission fluid cooler passenger side, engine oil cooler driver side
-Summit Racing auxiliary transmission cooler in front of the condenser
-Improved Racing engine oil adaptor/ 180 oil thermostat and AN 10 braided SS oil cooler lines to the driver side DeWitts engine oil cooler


Looking at my track day file, I see the following notes regarding maximum temperatures noted at two different days at Laguna Seca:


June 2016-
Transmission - 250
Coolant - 220
Oil - 260
Note- 107 degrees outside air temperature at the rest stop on the way home, 3 PM.


May 2016-
Oil - 248
Transmission - 235


I was back at Laguna Seca in February 2019, with all new air dams, max temperatures were below those noted above, but it was a cool day.
Scheduled to be back to Laguna Seca again July 29, we will see-

 

I think I found the culprit. I had been thinking that the duraflex spoiler shouldn't impede the airflow as it simply breaks the flow into upper and lower, but in fact it extends too far and reduces the air channel under the spoiler to about 3". This is way smaller than the normal air chute that exists without the spoiler. After some cutting and reinforcing the fiberglass I have a good under air chute again, so looking forward to my track day tomorrow in 95 degree temps to see how it goes. Image attached to show the splitter style.

 

I have cut the front license plate area out (leaving the screw holes for the filler plate) and take the filler plate off when at a track, hopefully improving air flow to the engine bay.

 

Thanks George, thought about that but it doesn't seem to put the air in the right place, and I really don't want to mess with the positive pressure from the bottom feed. For all I know it will end up pushing air out of the front instead of in.

It's still too hot, proven at Thompson last weekend. I think the next step is a Dewitt's rad with OC. Water temps aren't bad since I opened up the bottom feed, but oil is still a problem. I'm good for about 10 min until it creeps into the 290s. I do flog this car well, and of course the faster I get the more mods are required.