Not at all, this is quite the interesting discussion... I will try to run the test tomorrow, weather permitting and provided I can find the thermocouple attachment for my multimeter.

 

I'm still alive. As cij911 wittingly explained, the reason I'm not affected is because I haven't got any brain cells!

Reread all your posts cij911. And the other genius here with a degree in physics. You two attempt to passoff your theories and hand drawings as hard, credible facts-- while downplaying the actual numbers GM retrieved from testing temps. Not to mention the actual cooling benefits instantly achieved from doing this "mod", again which other members have already reported on.

Lastly, I hardly call 10-20 degree drops a "slight improvement". But to each his own.

Just because you're scared of the absolute remote chance of carbon monoxide poisoning and rear window blowouts doesn't mean this "mod" doesn't lower underhood temps. Period. And you know what, it's a chance I'm willing to take.

In case you missed it, I've highlighted some interesting parts for you to read, then reread and try to comprehend (keep in mind, the man works on cars like ours):



So, it's proven. It's likely an unknown variable is allowing for cooler temps after removing gaurd/liner. An unknown variable mind you, you probably aren't taking into account. Simple as that. And until further in-depth testing, I will rather rely on what's already been tested and proven then your theories and assumptions.

 

They are not our theories , they are laws of physics . I'm not questioning the drop in temperature , but the reason why . It may be because by letting air into the intake area of the air con ( every thing forward of the bonnet seal ) is act as a heat soak . Things that maybe getting hotter - fuse box , suspension tops ( not a good idea with airmatic struts ) auxilary battery and any thing else located in that area.
Why is it no longer possible to have a discussion with you with out you getting pissy ? I have no axe to grind and there is nothing wrong with a good healthy debate .

 

I apologize if my post offended you, mainly it's cij911 that is getting personal all while refusing to accept the fact temps do drop and your rear window won't blow out. So I still don't know what the argument is here. You two add new arguments with every new post. Never satisfied. We went from first denial of any initial drop in temps due to laws of physics to after being presented with numbers, CM poisoning and rear window blowouts. And now, it's about other parts getting hotter.

I'm all about a good healthy discussion, and I would love to read what further testing reveals, however if your idea of a good debate is speculation versus actual recorded data then I digress and will agree to disagree. Come with numbers and I can take your arguments seriously. I mean, have you even done this on your 211? Because if you have, that would certainly lend more credence to your arguments. On the other hand, if you haven't you're just left with what adds up on paper and in the real world, things don't always line up with what's on paper. Yet again as the numbers have already demonstrated.

 

Prada - I was trying to help you ...

Please show your IATs before and after and I will believe. I logged the car with and without the gutter, and IATs in NO WAY dropped 20 degrees. In fact, I saw no difference. I will not debate this with you any longer. Best of luck

Greasemonkey - I have a DT222 and and will be logging the bay temps, along with logging IATs with OT2, and posting the data later this week. I am really not sure how your car would have become faster with this mod, as it would have to lower IATs to effectively allow you to run more timing. Maybe placebo ? No idea, but I am very interested in learning....

 

The 20 degree drop was not the IAT, it was underhood engine and surrounding surface temps. Through the many discussions in this thread I think that has become misunderstood. Not placebo, and the way you are wording it is not what I meant to convey...The car did not become FASTER, but a better way to say it would be more CONSISTENT. Before removing the liner and panel, after a few hard pulls driving to lunch,the car would lose power, you could feel the heatsoak without a doubt. After a while I could almost predict I had maybe 3 good pulls to showoff for the passenger before the beast settled down.The supercharger was not shutting down,it wasn't that severe... but the engine was much less responsive after the initial couple full throttle episodes. After removing the panel, the car starts out strong and stays strong, that is once it has warmed up. Remember, I have Kleemann headers, and quite frankly my O.C.D. was kicking in after I installed them as I kept opening the hood to what can be described as a scorching hot wall of air hitting me. I was concerned now, and second guessing whether I should have had the headers coated, or not even installed them. As I looked under the hood I realized the hood was 100% sealed around the top of the engine, just like the E320's, E350's and CDI versions are. I thought to myself this may be OK for a stock engine, but the heat from the headers concerned me. I removed the insulation and panel, and have been very happy with the results. No more wall of blazing hot air when I open the hood. Remember, I've worked on hundreds of these cars, and that first open hood experience told me right away there was too much heat hitting me...not exactly scientific but I knew it was hotter than any other 211, or even E55/E63 I have worked on. My findings may be more pronounced than a car with the stock manifolds, and remember this is in Florida in blazing hot summer temps..

The IAT may not be an accurate test either. The biggest temp difference I saw was on top of the surge tanks. These are after the IAT sensor in the air flow.

 

I'm no engineer, but wouldn't "heat" do what "heat" has done since the beginning of time? "Heat" moves to "cold".... I get that air pressure is traveling over the hood at speed. I guess what I don't understand is how that air pressure (not sealed) can stop "heat" from doing what it naturally does and move to colder temperatures.
Although I don't practice, I did get my Universal rating in A/C, heating, and refrigeration while in the military.

 

First part of the experiment done ambient temp
http://imageshack.us/photo/my-images...ep18160040.jpg
I switched of the air con , got the car fully warm and placed a themometere in the air out let and left it for 10 mins
Hear is the the temp
http://imageshack.us/photo/my-images...ep18151823.jpg
The temp out of the out let was 26 c

I then removed the plastic grill and done the same test
After 5 mins
http://imageshack.us/photo/my-images...ep18160523.jpg
The temp was up to nearly 50 c after 10 mins it was of the clock .
I also put a cigarette lighter over the inlet on the bonnet , and rather than blow it sucked the flame in .

Other things to note , every thing under the bonnet got heat soacked , the suspension tops were nearly as hot as the engine , the brake fluid res was also as hot as the engine .

So too sum up , with the trim removed , the heat is drawn into the air con via the inlet , every thing that was cool is now hot and the most worrying thing is that most of the air drawn into the car is drawn from the front at a standstill .
So in traffic as the inlet is fairly low don't pull to close to the car in front , Especialy if it's a bit smokey as you are at the right hight to pull it into your cab .

I then replaced the trim panel and with in 10 mins the suspension top struts, brake fluid res and the cab air in take had cooled down and the air in to the cab was back to normal levels .

 

Marc - Great validation, but still there will be doubters.

The other issue at hand is the benefit of the headliner. My guess (guess being the operative word) is that Greasemonkey felt a difference with the liner removed due to the fact that the liner was retaining heat. My guess (guess being the operative word) is the headliner is designed more for noise reduction and could be a heat sink (no idea).

So I think the two mods should be addressed separately and hope to add to your data by week's end.

 

The only thing the seal does is protect the electrical components & your engine from water leaking in.

You can remove the padding on your hood but that might damage your paint. The heat can discolor the paint.

 

I agree all the padding dose is protect the hood from heat , and also to isolate the engine noise ?
Can't see nothing wrong with removing it .

 

Your test seems pretty irrelevant when we take my initial comments regarding this "mod" into context. Before I get to explaining this let us note, I have no "axe" to grind with you and will be simply addressing your results in hopes of clarification.

I saw no numbers indicating before and after engine bay temps-- at speed or at a stop with and without guard/liner. I also saw no pics of the car in question. A couple pics of a thermometer with varying degrees is hardly "validation". Furthermore, I can't recall arguing (or even caring) about AC temp changes at a standstill. I say standstill because at speed the difference wouldn't be nearly as drastic because there would be outside air entering the bay, so the heat wouldn't nesseairly just sit and so easily transfer to other components as freely. The temps in the bay would be cooler while driving due to venting. Your test only assumed what seems to have been convenient for your argument. Maybe unintentionally we are getting things confused but there's a big difference in regards to drops in underhood temps with guard removed vs. AC temps with guard removed at standstill. A big difference, and even assuming your test is accurate, to me it's not that big of an issue. AC isn't always on lol

Cij911, I'm a bit confused and I would like to draw your attention to a post you made here earlier:

So before you were able to "see how removing it would help draw hot air out", and now this test is your validation? Lol... Do you even know what your arguing about here anymore?

So in synopsis, we all agree it lowers underhood temps by venting. Cij911, I kinda think you still do? And Marc, you are saying yes just not when the AC is on? Or yes at the expense of a warmer AC at a standstill? And we all agree it makes the car louder? Only some "think" the heat will damage your hood? Some things to consider, apparently.*

And btw: the flame was only sucked in because the AC was on. And again, at a standstill. The flame won't just magically make its way in there if only guard is removed. Or will it...!!?? Nope. Just tried it on my car.

 

I will leave you to it , if your happy drawing the heat from your engine through your cabin , cooling it by your car air con good luck to you . But when in trafic do not sit to close to the car in front , because you are you are pulling in your fresh air to the cab through your front grill .
And yes it dose drop the engine bay temps , never claimed it did not say it didn't . But the reason is because it's drawing the heat through the car , but cooling it by the air con
Great mod but one I would not recommend .

 

Prada - You clealry have an axe to grind, so have at it...I have said several time that I could see how heat would escape through the grate, but only at low speeds or at a standstill and I also agreed early on that I did not think it would be wise and would have to look at the engine bay more. I understand physics quite well thank you.

Have a wonderful day and good luck with your "mod".

 

I can vouch that after driving in the rain and getting a car wash with both, liner and vent guard, pieces removed, only 3 very little drops of water were apparent near the Y-Pipe, if that. Definitely doesn't let the water in without it. So far, so good.
Note: These results are for my CL

 

Did some testing today, got some video with a smoke machine around the hood vents and cabin air inlet/filter area. My conclusion at the moment- at idle, with recirc mode off of course, there is a mix of both fresh air from outside the hood, as well as hotter air from under the hood being taken inside the cabin.
This probably isn't a surprise to anyone. Do I think the underhood temps are running cooler because ALL the hot air is being drawn into the cabin? No way. I have a feeling the underhood liner plays a more significant part in cooling the surge tanks than removing the actual plastic shield. Currently running at the moment with hood liner removed and the panel installed again, to test the theory. . Need some hotter days to compare to my old measurements. However with the panel removed, and the engine fan running on higher speeds (it was 90F outside today) there is a lot of hot air being pushed out the hood vents, at the same time the A/C is sucking in fresh air at the far end. The rear firewall, although not 100% sealed at that point, is still dividing the hot and fresh air. There is of course some mixing of air going on under the hood. With the Panel reinstalled, this hot air has to go somewhere, possibly being blown downward and out the bottom of the car or more likely through the transmission tunnel.

I know my surge tanks and underhood surface temps were cooler after removing both pieces. Now I am trying to figure out if it was just the liner, the panel, or both.

At speed, is another debate. I will let the videos speak for themselves, so get ready for more debate

Uploading video soon..

 

I have an axe to grind because I point out your inconsistencies and have questions about this test? Grow up, no ones doing anything more here then attempting to identify and label the pros and cons of this modification. In an effort to further continue this discussion and stay on topic...

Marc, I recall I previously posted there isn't a difference in AC temps with guard removed and despite this test, I'm still inclined to believe the same. I think the reason you got the results you did is because you were stopped for the entire test, which is a considerable amount of time. Considering we drive our cars, I believe it's important for the final results to take those same temps while the car is moving. And also, I would like your opinion on what would happen with AC off, and no "suction" from the inlet. Would the cabin still be warmer? I would say no. But I would also say I haven't noticed any temp changes since day 1, so maybe *I* don't notice as much as others would.

Hope we can continue this discussion without anymore hard feelings. I'm pretty sure we all just want to know exactly what happens with this "mod".

 

Is there any option here to direct upload video as opposed to a youtube link?

 

Did you happen to get temps inside before and after to compare with Marc's numbers? Just wondering how significant it is, I swear I can't feel a difference.

 

When the car is stationary this makes complete sense....(I too guess the headliner is acting as a pseudo heat soak even though that may not be its intended design, which I am guessing is more NVH related...)

Looking forward to seeing your videos

 

Didn't have a chance, and not sure it's really relevant. If you are running the A/C the car will automatically adjust the blend door to compensate for outside air temp changes.

Also, at speed, the A/C ECU will exponentially close the recirc door to prevent a ram-air effect from increasing the air flow speed into the cabin. Another over engineered feature from MB

 

Yes I agree all my tests were stationary , I currently have no wheels ( still at the machine shop ) no brakes ( waiting on mounting bells for the brabus system 3 brakes and for parts for a brake cooling kit ) ) and no inter cooler ( having a new one made )
I currently can't drive for another 3 weeks , until I get my licence back

 

So the temps shouldn't be affected by the guard because of the AC ECU? And if that's the case, why did Marc see an increase in temps?

 

I did switch my air con off , to prove that the air coming in was above ambient temp , it went over 50 c with it removed and dropped down to just bellow ambient with it replaced (still with the air con switched of ) but the fan running both times .the only reason the air with it removed got hotter than ambient was because it was also pulling air n through the engine bay . .

 

Guys I'm not saying it dose not lower under bonnet temps , I'm saying the reason is because you are drawing it into the car through under the hood . With doing this it's fine unless you have an exhaust leak , or sit behind a car in traffic because you are pulling the cabin air in through the front grill , just above every one else's exhaust hight .
With my test stationary , interior fan running the grill we still sucking in air rather than exhausting ,