Evolve Automotive carried out a comparison test on the BMW M6/M5 OEM chargecoolers vs CSF chargecoolers.
One of the few companies to actually take the time! Interesting results
Test Results – Stock M6/M5 Chargecoolers
Inlet air temperature (post chargecoolers): 30C
Test Results – CSF M6/M5 Chargecoolers
Inlet air temperature: 25.5C
Test Results – Summary
OEM Chargecooler Difference (Ambient temp vs Intake Air Temp): 14C
CSF Chargecooler Difference: 3.5C
Points of note
The results show the CSF chargecoolers keep the Inlet Air Temps (IATs) much closer to ambient than the OEM chargecoolers even though the ambient temperatures were higher for the CSF chargecooler test.
Does this mean the CSF chargecoolers are superior to the OEM chargecoolers?
Probably, but with there are some other things to take into consideration when looking at these figures.
From the diagram on the right
Low temperature circuit for cooling the charge air and the Digital Motor Electronics:
A Coolant radiator
B Additional coolant radiator
C Electric coolant pump for cylinder bank 1
D Charge air cooler for cylinder bank 1
E Expansion tank
F DME cylinder bank 1
G DME cylinder bank 2
H Charge air cooler for cylinder bank 2
I Electric coolant pump for cylinder bank 2
J Additional coolant radiator
I have to assume that the water pumps for the charge cooler circuit are adjustable and only adjusted according to the inlet temps of the chargecoolers and possibly according to the IATs. ( If the speed of the pumps do not change the rest of this article is mute point.)
With lower ambient temps I would assume that the pumps would be programmed to flow less water than at higher ambient temps.
In addition to that, it is also possible that the BMW DME also uses the IATs to control the pumps and therefore the flow of water through the chargecooler circuit.
What does this mean?
Because the CSF test was carried out at higher ambient temps it could mean that the coolant flow through the chargecoolers was higher which would give improved cooling.
The BMW DME could also allow the IATs to reach a threshold. For example when the difference between IATs and the ambient temperature goes higher than a certain number the coolant flow could be ramped up significantly.
Or for ambient temps up to 20c, the flow through the circuit was at its minimum. Only when ambient temps rise above 20C does the flow increase, as an example.
Basically, because the ambient temps were different between the two tests, it could have had an effect on how much water was flowing through the circuit and this would directly effect the results of the test.
Does this invalidate the results of Evolve’s test?
How can the test be improved?
Test the OEM chargecoolers and the CSF chargecoolers back to back at the same ambient temperature.
With the same ambient temps, at least we would know that the coolant circuit of the chargecoolers were operating in the same way which would make the two products and test results directly comparable.
M6/M5 Chargecooler Test Comparison – Summary
As it stands, the test results show that the CSF coolers are better (which they probably are) but is this solely down to them or because there was more water flowing through the chargecooler circuit?
Is this article complaining about the Evolve test?
Absolutely not. As I said above, this is more testing that the majority of firms carry out and it does gives us some baseline info which we can build on.
My personal thoughts
The CSF parts are probably better, the real question is by how much? And Are they worth the expense?