The insulation. Damn, 20mm thickness ( out of stock for 25mm one ), is so freaking FAT !!!!
I ended up only using 2 of the 3 I bought. I use 3/4" ID and the 1/2" ID. The 1" ID left standing by.
Preliminary insulation. Crude yes ....
I can't access deeper/lower than below, for insulation. Too tight a space. >T1 = Suction at compressor
>T2 = Suction near ABS Pump
<T1 Condensor output pipe ( Liquid Line ) after drier.
<T1 Condensor output pipe ( Liquid Line ) after drier. No space to insulate at that bend. Too tight.
<T2 Engine Bay Ambient Temperature as per air blown by fan . Very windy area here. Tornado Alley
Summary. Bare is no insulation
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The sun glare is so irritating. Left thermo display data almost un-useable.
Starting the engine after STATIONARY TEST. Waiting period : 10-15 minutes. Preparing to cruise. Below 2 images are +-10 seconds after engine started.
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Time code is for total A/C ON time.
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Yes, total test time is not the same.
Too bad I did not record long enough of engine shutdown heat soaking for the INSULATED one.
If only MB has sensor on the low pressure side ( suction ), I can do superheat calculation.
I tried calculating the subcooling, that is all I can do.
This test may not be scientific enough, as I can't create 100% same weather as in ambient temp, humidity, sunlight strength, vehicle velocity and yada yada.
But, it does seems to show that the insulation will do good in stop and go traffic. Must find away to make it a nice looking insulation like OEM if possible.
Later or tomorrow I will post the STATIONARY BARE vs INSULATED, but this MOVING/CRUISE is more fun.
Thank you for collecting and organizing your dataset in a friendly summary table.
Some temperature deltas are as impressive as your wrap job. Makes my experimental wraps look more amateurish. The way your wrap includes even the soft rubber section looks nicer....
Let me suggess you don't rely on glued tape and through a couple tiewraps over the wrap to secure your foam wrapper. You don't want it to go hug the exhaust pipes. 😅
In 2 weeks I have to drive in 105°F weather... so I am going to spend more time to minimize heat transfers near all 3 extremities:
1- line section near condenser outgoing (important !)
2- line section near compressor suction (summer only)
3- line sections near firewall (hard to reach!)
section near firewall
Did you wrap your HEAT EXCHANGER section (concentric pipe section near brake booster) to keep most of the outgoing cold line transferring into warm incoming pressure?
Since my car is RHD, the freon Y pipe split is as indicated below and is under the main battery.
This section can be next on the list, if do-able.
Let me suggess you don't rely on glued tape and through a couple tiewraps over the wrap to secure your foam wrapper. You don't want it to go hug the exhaust pipes.
Let me google around for suitable material or fabric. Exhaust pipe is far away, quite safe.
Tie-wrap tend to press the EPDM air-cell, the air-cell is what made the insulation good and I want to keep the roundness as true as possible
It is quite fragile this aeroflex outer skin. Maybe I will try this adhesive also from Aeroflex for its EPDM air-cell, 125C continuos operating temp is good enough https://www.aeroflexusa.com/wp-conte...eet_041621.pdf
These Aeroflex products look pretty good 👍 remaining bare pipe 🤣
The difficulty with wrapping the heat exchanger is Benz has it layed down really tight over front tower with very little clearance to insert any foam insulation.
If I have to... I'll just use multiple layers of thin kitchen plastic wrap to cut down heat transfer into bare aluminum -or use thick ziplock freezer bags taped over the seams...
I look forward to stationary comparisons when everything heats up pretty toasty with only the smart engine fan going supersonic 😏
My T1 middle , the air vent temperature, sometimes go banana. I think the soldering is loose inside the yellow connector.
This thermocouple is fragile ( due to being so thin Chromel and Alumel wire they are ) at the yellow connector and how the OEM secure the cable entry into yellow connector matters a great deal.
Since the jacket is actually fiberglass material for super hot temperature use, it releases micro needle like fibers = SO ITCHY !!!!
Some measures seem counter intuitive at first if you're not minding what they represent: car stopped getting baked in A/C heat.
It's not trivial to dig a solid conclusion based soly on these data. We can read the chart both ways... some parts look better, some parts seem worse to the point it makes you question the sensor installation.
What does stand out is you did an awesome job building this test setup. I don't know if you want to improve sensors installation on a non-profit study.
The difference is a welcome improvement to a system working at its upper limits in summer traffic.
I am still trying to understand HVAC. So I really can't comment much. I do like to experiment though ... ha ha ha.
Even though the simple target is to remove as much heat as possible, the unique state of change of R134a between gas and liquid state is something I am still trying to wrap my head around.
Subcooling and superheat, that is the key right ?
Between bare test and insulated, I discovered that my left air vent near the door was not opened up 100%. So the middle left vent where I had my sensor T1-Middle was getting more airflow actually, during bare test.
I opened up that left air vent during insulated test, and I noticed T1-middle vent read like 1.5C ish higher/hotter as the left vent now gets is proper maximum flow.
The T2-middle sensor if I were to rely on it, I should have mount it in a more rigid fashion, so it can provide repeatability. Hence I never refer to its data ,
I rather use thescanner iCarsoft B10/4 interior temperator sensor. I must check where is this sensor actually located at.
The scanner B14 - Outside Temp Sensor is indeed the one at the left lower bumper. I tried spraying with cold water and it reacts.
However the scanner has another no sensor number data called ; Outside Temperature , I do not know where that data comes but it shows correct oustide air temperature
If I were to install another thermal sensor/s, I think under the battery where the pipes are closes to the evaporator would be a good data point.
I still have 1 more dual channel display and 2 long wired thermocouples , so 2 more data channels is possible.
I have insulated the B14 - Outside Temp Sensor
Hoping that if it is more accurate to actual ambient air temp and not corrupted by the engine bay temp, whatever algorithm using that B14, can do so with immediate accuracy.
What I discovered was, during stationary, the fan will blow the radiator and that hot air comes into the engine bay. The engine bay is then sort of having positive air pressure and the bumper portion where B14 sits,
those small opening/slits I marked with red lines then allows the hot ambient air to escape out forward to the sensing tip of B14 and that is why it gets FALSE hot fast.
If the car move at least 60 KM/H or more, the venturi effect created by the under-carriage moving at speed and the positive pressure wind velocity at that speed, will suck/push out engine bay hot temp out
from firewall to under the car .....as such B14 will then read true ambient air.
I am not tempted to close those slits, as at high speed those opening should do benefit.
So guys...what's next for this experiment ?
Off topic.
BTW, I am going to revisit N3/10 ECM Low Voltage and try to improve it.
Here is the freon pipes from suspension strut area to the firewall...........
I am doing this is also for looking at the F32 PreFuse close up .
Right Hand Drive - Battery removed
Battery Tray Removed
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Good thing I am doing this. I found another ground point which MB never even bothered to document. Could be because E400 with M276 3.0 is a "Pariah" hahaha. RHD version is even more "Pariah"
The suction pipe converts then to hose and heading to middle of the car to actual firewall. The Liquid small pipe stay as pipe.
For suction/gas hose. Thin 3mm insulation given by MB, but it is more of chafing protection I guess.
So these two freon pipes heading to expansion valve/evaporator which the position is indicated in green.
Suction hose end is the L bend aluminum and into TXV
TXV view from right side of car to middle of car
Next to TXV is the heater core, connected to the coolant hose from engine block V end as input and its return hose to front of engine near the coolant recovery bottle.
Below is the coolant PLASTIC pipe at end/flywheel side of V block towards heater core. This plastic pipe is something I fear big time, because it has to be replaced by year 10 or 2024 if
I want to keep this car beyond 10 years.
Porsche V8 has something almost like this, I mean the cheapo plasic as coolant line inside its V-bank and it DOES break apart, my friend's Cayenne already suffered that.
Funny enough, the new updated component by porsche is aluminum hahaha ....cheapo bas*tard !!
The cost of this plastic coolant pipe is no issue, but I probably, 85% probability, need to lift out my engine just to do this replacement !!!!!
That V block azz plastic pipe for coolant is then converted to a rubber hose which goes to the heat shield and then to heater core.
Close up. This hose 90 degrees bend, is now by position very close to the expansion valve, TXV.
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Now I finally can see all routing of heater core hoses and freon hoses .
It's hard for Benz to hide anything away from you ...
While you have your TXV in sight, wrap it's tiny bulb sensor so it only picks discharge temperature with minimal external influence. TXV is what keeps the Evap. above freezing by *regulating* refrigerant outlet temperature.
In the US w212... the A/C lines are routed under the master cylinder brake lines going towards the center.... so really no easy way for me to wrap that last section before entering cabin space 🤣
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I looked at the fan and radiator shroud for improvement opportunities: it is nearly 100% perfect as far as air not bypassing around. The fan perfectly draws all its air from the very front of the radiator + condenser stack.
👍
I am closing the project. Maximum insulation done. Can't do better.
Overall result is good. Heat soaking reduced after engine shutdown. In a stop and GO driving situation, the extra insulation shines.
I tried my best to have insulation to OEM look
This final insulation extra areas are :
Liquid Line out from condensor.
Was
Now
The assisting material. Ready made with adhesive backed, 3mm foam. Me too lazy to use liquid glue, but I already bought the liquid glue though. Malaysian made.
I bought extra 9mm and 13mm thickness type tube insulator. 1st time was all 20mm wall thickness.
Few things to note :
01. The icarsoft scanner reading Evaporator temperature is not the physical aluminum temperature of the H Block expansion valve gas/cold side as HVAC engineers would measure.
It is air temperature sensor closest to Evaporator, low side of the evaporator. See WIS below : https://mbworld.org/forums/e-class-w...ml#post3371070
So 3.80C coldest I seen is decent.
Below is a 3 minute stop ( engine running ) at a rail-crossing in a hot day.
You know, If I ever do my wiper motor ( pray it won't happen )........., that means I got to remove the plastic water shield between front windshield and above firewall.
I would then migh as well insulate more of engine bay heat towards cabin.
MB uses heat shield defence, before actual firewall. As seen below : the shiny aluminum side of the true engine bay heat shield.
The one facing the engine get that black felt-like fabric extra layer which is supposedly a sound shield material too.
The one facing the firewall is the naked aluminum. We can then stick on 9 to 13 mm EPDM insulator sheet version on the naked aluminum, like what I use on the HVAC freon pipe, but a sheet type. https://www.aeroflexusa.com/wp-conte...eet_102120.pdf
This may help sound absorbing too, foam type material can absorb high frequency noise.
Came late to this thread, what can I say? Very, very impressive work
In case you feel to do it all over again, you could estimate the best thickness of the insulation before installation since you should be careful not to add too much thickness to the pipes.
It applies to insulating cold lines as well to extremely hot pipes (steam pipes). There are situations that it is best to not add insulation at all, not in this case as proven by experimental evidence.
I have a quick trick to keep my HVAC system cleaner.
I simply tape a fabric softener sheet to the inlet.
It acts as a prefilter ahead of the car own HEPA cartridge in the passenger foot well.
free pre-filter: 6 month dirty !
Change it for free in 5mn as often as needed.
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OK, time for the stupid question... Where is this inlet? I have looked near the Cabin Air Filter, and don't see the square ductwork inlets in your picture.
This is a great idea, and the wifey will not miss the Bounce sheet at all.
You can find your HVAC air-box under the hood on passenger side mounted above AGM battery.
Enhanced HVAC Pre-filteration box
If you look closely, in this instance, I have a sheet installed on both inlet and outlet sides.
Rainy climates:
It may be best to also consider this box as an air dryer because it features a sealed water outlet spout. Try to install filtration on air outlet only or both regardless.... who knows ? 😷
The bottom line is these spent fabric softener sheets get loaded with dirt super fast and keep rain water from splashing onto the HVAC Blower area - So I see these evidence as beneficial win-win to have at least an outlet prefilter.
Let see what others get
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