I'm about to open a can of worms.
Last week I adjusted the calibration of the temperature sensors in my A2W intercooler system, and they are now very accurate, to within 1 degree in fact. I achieved this by obtaining the specs of the Adaptronic e1280s ECU's internal voltage divider circuit for the temperature inputs, then populating the calibrations based on the official datasheets for the sensors. I found that the calibration that I had before wasn't far off (about 2-4 degrees), but I wanted to make the calibration perfect for the next step.
Prompted by the recent warm weather, I decided last night that I would datalog another drive to generate some more results for my A2W intercooler setup. The ambient temperature was about 23 degrees C.
I already did this earlier this year, but last time the conditions were different, and as some of you may know I've been re-thinking my A2W system in recent months, so this time I wanted to determine if my setup needs improvement, instead of trying to prove that it is already sufficient.
So, here we go, a plot of the exact datalog retrieved from my ECU's onboard flash memory (note to future readers...this is with my OLD A2W intercooler setup):
Observations:
- 3 main boost events, at 8, 14 and 32 minutes in the log.
- As forum member 'cogs' mentioned last time, the slow decay rate of the temperature sensor readings in some low-throttle cases is a result of the thermal inertia of the sensors, rather than an accurate representation of the temperature. When on boost with heaps of airflow over the sensor, the reading IS accurate though, because the additional airflow causes the sensing element to heat up quickly.
- From 14-22 minutes on the log, I was cruising at 90-110km/h on the motorway, and the A2W coolant temperature can be seen reducing noticeably during that time
- Worst case air temp before intercooler 110 degrees C (after a few seconds at 20psi of boost), down to 57 degrees C after intercooler, which is OK but not great.
- For the first 6 minutes (and at least another 5 minutes before the log started), I was idling in the garage while mucking around with some unrelated ECU settings, and during this time the A2W coolant temperature heat-soaked from 23 degrees C all the way up to 38 degrees C...not good at all!
- I was also idling, at traffic lights, around 7, 12, 24 and 25 minutes in the log, and the A2W coolant temperature can be seen heat soaking during those short periods too.
- If the A2W coolant was closer to ambient temperature, as it would be with a heat exchanger at the front of the car, then the worst case post-intercooler temperature probably would have been down around 40 degrees C, or even less, which would be an excellent result. The intercooler barrel already appears to be doing a decent job, given the excessively high water temperature inside it.
So, after all that, what's the point of this post, and why did I mention a can of worms? Well, a number of people did try to talk me out of having my A2W heat exchangers in the engine bay, instead of having one at the front of the car like everyone else. I'm basically here to admit that I should have listened, and I'm sorry that I didn't. Everyone knows I want everything to be just right on my car, so there is no point for me to hide my regret hahaha. I must emphasize that I am entirely happy with how the car drives and the substantial power that it already has, and if I never analysed any log files to look at the temperatures I would have no reason for concern, but being the perfectionist that I am with my car, and with the irrefutable results shown above, I now feel that I may make a change to my setup after all.
For those of you who warned me right from the start, please don't rub it in and make me frustrated...please just be happy that I have taken the necessary analytical steps, and I am considering making some changes to my setup. I just have to try not to feel regretful for not doing it right the first time lol.
Another bonus of this post is that it highlights the major heat soak disadvantages of having an A2A intercooler in the stock side-vent location in the engine bay (an A2A intercooler in that location would be affected by heat soaking in a similar way to my A2W heat exchangers, although maybe not as badly because there is no water being heated inside an A2A).
Also, once (if) I make some changes to my setup and post the new results, there will be some extremely useful before-and-after comparison information to show the difference between cooling something via the engine bay side-vents or via the front of the car.
On an unrelated note, if I do decide to make some changes, I may also change my intake manifold/plenum, which is something else that I maybe should have done the first time.