In a truly excellent thread elsewhere, an adventurous team examined the engine water and oil, and transmission temperatures of a tracked A8 C7 Z06. And on that basis, this same intrepid team pursued a series of cooling strategies.
The purpose of this post is far more modest. We tracked a naturally aspirated A8 C7 Grand Sport at high altitude during the summer and experienced the same high temperatures and resulting “limp mode” penalties.
Why did this happen?
Water at altitude boils at lower temperatures. For Colorado tracks, at altitudes between 5545 and 4913 feet, water boils on average a 201 degrees F. instead of 212 F. In comparison, at The Circuit of the Americas in Austin, TX, water boils at a lofty 211.06F.
Summer heat and humidity levels at altitude also play a considerable role. On 8/22/2020 at High Plains Raceway in Deer Trail, CO, air temps hovered between 94-98 degrees F., with 5% humidity, and an air density of 76.82%. Those data mean that we were effectively running at an altitude density of 8745 feet! God only knows what the surface track temps were, but our tires were greasy by session’s end.
So here is what we did to solve our high engine water and oil temps.
Mode 1: delete of the oil/water block cooler and install of a remote air/oil Setrab cooler (6-series Setrab ProLine STD Oil Cooler, part number 50-616-7612. This oil cooler was part of a kit that included an air box that resided on the driver’s side and doubled as a brake cooking duct. While a nifty install, the kit, unfortunately, did not address the high engine oil temp issues as the capactiy (23,000-32,000 BTUs) of the cooler was not sufficient for the task (rated at 190-220 HP).
Mode 2: To improve the oil cooling problem, we installed, in series, a second oil cooler (Setrab ProLine SLM, part number SLM 592-10) above the front auxiliary transmission cooler and before the main water radiator, leaving an 8 inch gap. This cooler was rated at 33,000-46,000 BTUs and for 325-425 HP. This arrangement has worked well with max. oil temps in the 270s F. Observed dash gauge transmission temps are a steady 200 F.
Mode 3: While the delete of the oil/water block cooler did improve the inherent performance of the OEM radiator, it proved not to be sufficient. Water temps in the high 280s/290s had to go. What fixed this issue was the install of a Ron Davis all aluminum radiator (P/N 1-16CVC7) filled with distilled water and one bottle of WaterWetter. Max water temps fell to a max in the 230s F.
Mode 4: While controversial, we next gutted most of the radiator fan shrouding’s structure to encourage air flow. This, along with the removal of the rubber seal at the base of the front windshield and the hood padding, both improved air flow through the engine bay and lowered engine heat soak.
The purpose of this post is far more modest. We tracked a naturally aspirated A8 C7 Grand Sport at high altitude during the summer and experienced the same high temperatures and resulting “limp mode” penalties.
Why did this happen?
Water at altitude boils at lower temperatures. For Colorado tracks, at altitudes between 5545 and 4913 feet, water boils on average a 201 degrees F. instead of 212 F. In comparison, at The Circuit of the Americas in Austin, TX, water boils at a lofty 211.06F.
Summer heat and humidity levels at altitude also play a considerable role. On 8/22/2020 at High Plains Raceway in Deer Trail, CO, air temps hovered between 94-98 degrees F., with 5% humidity, and an air density of 76.82%. Those data mean that we were effectively running at an altitude density of 8745 feet! God only knows what the surface track temps were, but our tires were greasy by session’s end.
So here is what we did to solve our high engine water and oil temps.
Mode 1: delete of the oil/water block cooler and install of a remote air/oil Setrab cooler (6-series Setrab ProLine STD Oil Cooler, part number 50-616-7612. This oil cooler was part of a kit that included an air box that resided on the driver’s side and doubled as a brake cooking duct. While a nifty install, the kit, unfortunately, did not address the high engine oil temp issues as the capactiy (23,000-32,000 BTUs) of the cooler was not sufficient for the task (rated at 190-220 HP).
Mode 2: To improve the oil cooling problem, we installed, in series, a second oil cooler (Setrab ProLine SLM, part number SLM 592-10) above the front auxiliary transmission cooler and before the main water radiator, leaving an 8 inch gap. This cooler was rated at 33,000-46,000 BTUs and for 325-425 HP. This arrangement has worked well with max. oil temps in the 270s F. Observed dash gauge transmission temps are a steady 200 F.
Mode 3: While the delete of the oil/water block cooler did improve the inherent performance of the OEM radiator, it proved not to be sufficient. Water temps in the high 280s/290s had to go. What fixed this issue was the install of a Ron Davis all aluminum radiator (P/N 1-16CVC7) filled with distilled water and one bottle of WaterWetter. Max water temps fell to a max in the 230s F.
Mode 4: While controversial, we next gutted most of the radiator fan shrouding’s structure to encourage air flow. This, along with the removal of the rubber seal at the base of the front windshield and the hood padding, both improved air flow through the engine bay and lowered engine heat soak.
