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Yep, the GM instructions do not ask for a cut out. But the image of the lower separator has rectangle spots that are suggesting they thought about it
What's Gspeed doing for the shelf coolers in their system? I looked around for instructions and couldn't find any on the website. While they don't use the stock location exactly they still have two coolers laying flat, venting to the underside and it works good.
Oh okay, that makes sense then, sorry for the dumb assumption. For some reason I thought I had seen instructions with a template to make a rectangular cutout under the aux cooler, but that must not have been the official GM instructions then. And since it does have vent paths already, I probably wouldn't cut any holes in the under tray either then.
I understand, the first three (3) coolers did not get the stitch welds, and you have identified two of them. JSIII had the 3rd and his is coming back. The cooler has to come out to get welded, no other option.
I think doing something like JB weld or other marine grade glue would be a better bet for us. We'll try that...
I think doing something like JB weld or other marine grade glue would be a better bet for us. We'll try that...
But if it doesn't work that makes welding that much more difficult. If you just want to hold it for now you could just use a chuck of foam and put the lower deflector back on to brace it.
Eh. Not true. Coolant at 200 degrees won't cool oil at 250 better than ambient air will.
My statement is about the difference between a system that can take the heat out of the oil quickly and one that cannot. I can clearly see the Dewitt I had on my z51 was taking heat very quickly out of the oil. My z06 is not acting as efficiently.
I guess there were at least four made without the stitch welds. Mine doesn’t have them either.
Sorry, I missed that one. I am going to make up some hanger brackets so nobody has to pull them out. Two brackets (one each side of the center fittings). slip over the core and tex screw into the baffle.
Last edited by Tom@Dewitt; 08-01-2019 at 05:01 PM.
Sorry, I missed that one. I am going to make up some hanger brackets so nobody has to pull them out. Two brackets (one each side of the center fittings). slip over the core and tex screw into the baffle.
Yes that would be great ! One wide bracket with 2 screws spanning both center edges of the cooler might be better.
Last edited by BrunoTheMellow; 08-01-2019 at 05:04 PM.
Great, I was going to have something like that welded up
first thing Monday. My machine shop guy is going to perfect his aluminum welding over the weekend. Keep us in the loop as far as shipping the brackets out. Thank you.
Yes that would be great ! One wide bracket with 2 screws spanning both center edges of the cooler might be better.
I don't think you can get to the center with the fittings and bosses. My thoughts were to use two clips on each side you could just slip on and drive the screws. One bracket would hold it, two would fix it for good.
I don't think you can get to the center with the fittings and bosses. My thoughts were to use two clips on each side you could just slip on and drive the screws. One bracket would hold it, two would fix it for good.
Ah you're right. Good idea tom. Thanks for looking into a solution quickly.
Thanks to @formula80_ca hosting me as a guest, I got to drive at Area 27 for the first time, and what an amazing track!
Beautiful facility, large paddock area.
3 blind corners that requires your trust, as well as a few deceiving corners that you really can take much faster than they look like (still working on it)
Area 27 club members also seemed to be very friendly.
This is the video of my fastest lap of the day. I am still learning the track, which is evidenced by confusion and late gear changes throughout my lap. Nevertheless, the car worked like a champ, and helped me make reasonable lap times, despite still not knowing the track. BUT, it also did overheat quite fast : (
Originally Posted by X25
Temps
This was the lowlight; most of the day was above 90 degrees F, and the car did quickly overheat:
The temp gauge issue: The temp shown on MyLink screen IS NOT CORRECT. When it was 91 degrees ambient outside, I was able to read 91 from OBD (which is also displayed on my video), but the MyLink screen read 94 degrees F. I don't know why it shows a wrong number, perhaps an attempt at GM trying to be like Apple, and knowing what we need to see better than us(!), but me, not likey. If you guys are reading the ambient temp from MyLink screen as a reference, please don't!
Temp sensor gets heat-soaked: Even if you're reading the ambient temp through OBD2, please note that the temp sensor also starts getting heat soaked as the coolant temps start increasing. As such, I'd only read the ambient temp from middle of the first lap, when the heat soak has not yet happened.
The track layout: Besides the ambient temp, I think this track is quite hard on the car on cooling with its many straightways. As has been illustrated by my previous UNCUT videos as well as the video below, the car ADDS heat at straightways (i.e. full throttle adds more heat than can be removed, even at 100+ MPH).
Result: At 91+ degrees F ambient, in about 6-7 (3-mile) laps, I hit 252 degrees F coolant, 295 degrees F oil before I let it off to cool down. As such, my current cooling is not adequate for these conditions. Looking forward to trying the same temps at my local home-tracks (in case this track is indeed hard on cooling), as well as 80 degrees F, which is more realistic temp for most of my track days before August.
The coolant temps never seemed to settle, until I finally let it go.
In short, at 91+ degrees F, I was not able to keep temps in check with my current cooling within a session (of ~20 minutes). I will try again at my home track at these temps as well as lower ones, and see if it makes any difference.
In short, at 91+ degrees F, I was not able to keep temps in check with my current cooling within a session (of ~20 minutes). I will try again at my home track at these temps as well as lower ones, and see if it makes any difference.
Does your company to any heat transfer analysis before putting something out to market?
I work for an engineering firm that makes industrial gas turbine parts. When we design a fix for an OEM thermal problem we have a very stringent design process:
baseline the oem, instrumenting the engine/area of the part. Record temps and pressures at various conditions, trying to hit the high stress operating points
Flow the oem parts. Dimensionally characterize them
Build a 1D(aft) and 3D(CFD) model of the oem
make design changes, brainstorming
update the models
flow the new parts
test the design with instrumentation. If successful, push well beyond design envelope.
He has a 2019 OEM radiator (52mm) and the Dewitts larger aux radiator.
X25 at this point. If you don't wan to cut up the bumper or deal with the oil system, a fan driven 3rd radiator inside the bumper cavity is your best bet (the 70 mm dewitts radiator will also help but I don't think it would be enough)
You can buy thermostatic switches for the fan and basically the whole kit from setrab. I can show you how my cooler is mounted for reference.
But notice that you got down from 250 to 225 in less than half a lap. That's awesome. Easily manageable.
Last edited by BrunoTheMellow; 08-03-2019 at 11:51 AM.
Does your company to any heat transfer analysis before putting something out to market?.
We do a lot of testing. Just last week a ran a week long analysis of a triple pass vs the single pass.
The end result was no improvement, but still looking for ways to improve.
Developing cooling for C7 racing requires actual field testing. There are so many variables (ambient air, track, driver, transmission) that makes it impossible to create an in-house lab to produce all these items. Now someone is bound to throw out the term "guinea pig" so let me do that first. We did not just make something and "hope" it works better than what was offered by the factory. The 57mm radiator was an improvement and the 70mm was enough to stop faults for some drivers. Another "given" item was the GM add on Aux cooler helped solve the problem for many drivers and this component had size and flow issues documented earlier. It was easy to produce a Aux that would work better but the unknown is what that means to field track results. Maybe that meant they could track on a hotter day or run more laps, and I call that an improvement. Unfortunately, in this thread, it is viewed as a failure because someone was able to fault out. The combo cooler was designed to give the A8 owners some options where none existed before. Obviously the TO is not a fan favorite, because of ONE track result and maybe that is not the way to go but let's see what others find before we pass judgement. The TC is still a viable option to add some additional cooling that was not there before. Our products are design to improve cooling and they do that. If someone is looking for a bullet proof, no fault system, you need to look at LG or Gspeed.
Last edited by Tom@Dewitt; 08-03-2019 at 12:33 PM.
He has a 2019 OEM radiator (52mm) and the Dewitts larger aux radiator.
X25 at this point. If you don't wan to cut up the bumper or deal with the oil system, a fan driven 3rd radiator inside the bumper cavity is your best bet (the 70 mm dewitts radiator will also help but I don't think it would be enough)
You can buy thermostatic switches for the fan and basically the whole kit from setrab. I can show you how my cooler is mounted for reference.
But notice that you got down from 250 to 225 in less than half a lap. That's awesome. Easily manageable.
Yep, the bigger AUX cooler was definitely an improvement, and is worth its cost. I also monitored the drop in temps during cool-down, and it was good (though the oil temps drop much slower; it dropped from 290s to 270s during cool-down).
Does C7AUX kit work? I think so, and it increases the time I can survive at the track. At 91 degrees temp at Area27, now I know that I can do a few hot laps before I need to cool-down. Perhaps at 80 degrees, I will get to survive the whole session.
Anything I do beyond this point requires substantial investment, as Tom has also alluded to. Well, perhaps that in-bumper radiator would be enough, but I digress. At this point, I'll wait for my second track car to be delivered (Atom 4), and see how it does. If it fares much better in hotter temps, I might as well just use that car when it's forecast >85 degrees F. If I hate that car for one reason or another, I might get back to my Z06 cooling, and try to improve it further : )
07-31-2019, 11:08 AM
