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X25 keep in mind that the ambient temp was 59* that day. It is not a linear ratio between ambient and engine coolant. Laguna is usually in 70-80*s in the summer. Thunderhill is 100*+ in the summer. I need the engine cooling buffer more for Thunderhill. I also think the car just runs better with the coolant under 200*. From other posts it's been said that timing is pulled at 212* engine coolant. If you watch IAT you will see that it jumps quite a bit when idling. So my goal is to optimize cooling, when airflow is minimal.
This also why I run a low temp thermostat. The thermostat temp is when it BEGINS to open. It could take another 10 degrees to fully open. I am trying to lower the temps as a buffer prior to going fast and when at low airflow.
I think the Dewitt radiator will help you a lot.
Originally Posted by X25
Thanks for the update, LagunaSecaZ06. Looking forward to your results at the track. I have to say, though, your temps of 212 degrees F coolant and 250 degrees F oil are already perfect. At around 80-85 degrees F ambient and 2300 ft elevation, I hit 234 degrees F coolant and 280 degrees F oil in 40 minute session with traffic at times ('19 Z06 with larger Auto Z06 radiator).
I brazed today and I hoped to have all new orders ready to ship out by next week Tuesday . Unfortunately yours crashed in the furnace and I'm on vacation next week. I will be assembling more cores tomorrow and they will braze them while I'm gone. So, I am looking at 6/25 for a ship date for yours.
Ok, thanks. I might want to add in an expedited shipping once its ready, if thats possible.
Pardon the poor photshop image but I feel a picture is worth a thousand words. Here is what I see happening if you were you just plug the back with foam. You would seal off air flow to the HX bottom 2", rendering that part useless. The combo unit is going to be very, very hot! Radiant heat is going to get carried into the HX and reduce the performance and power function.
Last edited by Tom@Dewitt; 06-17-2019 at 12:55 PM.
I should probably start a new thread on the one section 32-C7Aux but let's see how this goes. If it is settled quickly I'll leave it here.
The tooling to stamp these cooler plates is only capable of making a plate 15.75" long and the GMPP/TOC is 19.5" long. So if we want to offer the very high efficiency "plate type" cooler for this application we have to live with a shorter width unit. Since the new C7Aux is taller, at 6.8" vs 5.0", the overall surface area is 1.5 times larger. I feel this will do a great job but the cut out will be different.
If the general consensus says make it the same length and cut out, then the only option I have is to make the core a "tube type" unit with taller (3/8") fin. This probably wouldn't perform as good as the plate type but it would still be a very good unit and it would actually cost less. Tube cores are a lot cheaper and easier to make than the plate type. So instead of a $650 kit you would have something like a $400 kit.
Tom I am sure we trust your judgement. Just give us the best core for the space. If a slightly smaller more efficient core is better, do that.
I think a lot of guys including me want to see a simple test. Run some coolant through the stock one and this one and show us the result! More flow with More cooling? Same flow more cooling? Etc.
Last edited by BrunoTheMellow; 06-17-2019 at 09:02 AM.
Is there any way to increase the size and make it just as wide with the best type for the job? We'll otherwise leave some cooling capacity on the table, and for those cars that already has the AUX, the cutout will not be perfect.
Why don't we consider two cores interconnected that uses the whole space and matches the width of the OEM cooler, if not even wider? In a way, it would work like a 2-pass radiator. If you don't use huge hoses for the inter-connection, it would look clean, too.
In other words, yes, I think we should not replace the aux cooler with a narrower one, even if it has more overall area, since we know that it could be even better! : )
It would be too expensive for just an add radiator. If someone is willing to test at the track I'll send you both. It just has to be a good test, with all the parts installed, same track conditions and ambient temperatures.
I just got some gorilla black duct tape at home Depot that's insanely sticky. If you put it on both sides of any gaps you have it will seal real well! I just used it on my car.
Last edited by BrunoTheMellow; 06-16-2019 at 07:10 PM.
Guys, when quoting...consider deleting duplicate photos and unwanted text. This keeps the thread shorter and easier to understand the point being made.
Tom were you aware that 2015-2016 M7 GMPP aux radiator routing is different from 2017+ M7?
2015-2016 splices into return line from oil cooler. 2017+ Tees off the main radiator hoses (oil cooler return line is left alone). Just in case your kit's hoses might change...
Tom were you aware that 2015-2016 M7 GMPP aux radiator routing is different from 2017+ M7?
2015-2016 splices into return line from oil cooler. 2017+ Tees off the main radiator hoses (oil cooler return line is left alone). Just in case your kit's hoses might change...
I did not know that, thanks. Why did they do that? Was the 2017+ aux radiator stock? Are the tees factory installed for future connection or are they part of the gm kit?
I did not know that, thanks. Why did they do that? Was the 2017+ aux radiator stock? Are the tees factory installed for future connection or are they part of the gm kit?
2017+ is stock, tee'd out/in the main hoses. Likely due to more flow out of the main hose vs after the oil cooler.
The gm kit ties into the oil cooler return line instead. I guess cause it was easier to implement as an after thought.
Interesting. I always thought the connection after the oil cooler is clever, since the coolant will be hotter there, and the small core will work more efficient.
IMHO, your discovery and verification of the stock GMPP radiator having 18PSI of restriction at 6GPM vs 3PSI for your 32-C7Aux radiator is just as big a revelation as GSPEED figuring out that the intercooler pump turns off because of air bubbles. I really think this is why your coolers will have significant positive effect on the Z06. If you were ramp up the 32-C7AUX radiator to 18 PSI what would the GPM be? Is the flow change linear? Can you post a clearer picture of the chart in your post??
This is really the key point. Given that bottom is sealed, I don't think the flow diverter is a big deal(although it would help) vs, the massive improvement in coolant flow. Due to the low restriction, this really changes the actual flow through the stock radiator.
Simple analogy. On a hot day, would your rather go from 1 fan blowing on you to 2 fans OR from 1 Bucket of water to 6 Buckets of water thrown on you to cool down?
IMHO, your discovery and verification of the stock GMPP radiator having 18PSI of restriction at 6GPM vs 3PSI for your 32-C7Aux radiator is just as big a revelation as GSPEED figuring out that the intercooler pump turns off because of air bubbles. I really think this is why your coolers will have significant positive effect on the Z06. If you were ramp up the 32-C7AUX radiator to 18 PSI what would the GPM be?
here's a higher quality photo. I am not sure if this is as important as the source of your coolant. Can the OEM oil cooler flow coolant faster than the GMPP aux radiator? That may be your problem. Maybe that's why the 2017+ cars pull directly from the main coolant line. That's basically unlimited flow.
FYI, Tadge stated the c7 OEM oil cooler is capable of 71,000 btu/hr (21 kW). Hard to believe as this is the capability of a 244 sq in Setrab oil cooler (roughly 10x13 core at 3 psid). So apparently its a great cooler, if you had 100 degree water haha.
The c6 z06 air to oil cooler was roughly 200 sq in (20.5 x 6.2 core) and was said to be capable of 55,000 btu/hr. Not sure at what air temp.
Last edited by BrunoTheMellow; 06-17-2019 at 04:39 PM.
06-16-2019, 10:38 AM
