Anyone try the BMS Cowl Filters?

[JPuehl]

I was browsing the burgertuning site and noticed the BMS Cowl Filters and then looked under my hood and realized that if I removed the cowl ducting was mentioned in the description, I would be taking the rear hood seal off and the cowl filters would be sucking the hot air from the engine bay. Has anyone tried these and if so how do they work? They don't seem practical for a car that's mostly a DD and a weekend warrior.

[ShocknAwe]

As much as I love BMS products and especially their service, IMO this is one of the few things out there that is a bad mod. Lose the rear hood seal, which affects aero and engine bay temps (in a bad way). Also lose your water protection for the filter element. None of these issues are major, but worth considering. Mainly just a way to lose 10lbs.

[Yeineken]

Originally Posted by ShocknAwe

As much as I love BMS products and especially their service, IMO this is one of the few things out there that is a bad mod. Lose the rear hood seal, which affects aero and engine bay temps (in a bad way). Also lose your water protection for the filter element. None of these issues are major, but worth considering. Mainly just a way to lose 10lbs.

Note Burger is in CA where they don't usually have to worry about rain. Also Burger only races on the drag strip. So every pound counts for them. I would only use their filters for track days to shed some weight; not for DD purposes.

[ShocknAwe]

Originally Posted by Yeineken

Note Burger is in CA where they don't usually have to worry about rain. Also Burger only races on the drag strip. So every pound counts for them. I would only use their filters for track days to shed some weight; not for DD purposes.

Agreed on all counts. Still dicks the hood to windshield aero and underhood temps though. Not that it matters on the strip.

[JPuehl]

Originally Posted by ShocknAwe

As much as I love BMS products and especially their service, IMO this is one of the few things out there that is a bad mod. Lose the rear hood seal, which affects aero and engine bay temps (in a bad way). Also lose your water protection for the filter element. None of these issues are major, but worth considering. Mainly just a way to lose 10lbs.

Exactly what I was thinking.

[rhodesman]

Originally Posted by ShocknAwe

Agreed on all counts. Still dicks the hood to windshield aero and underhood temps though. Not that it matters on the strip.

Could you elaborate on this? I did the M3 Cowl conversion and saw a nice decrease in engine bay temps on hotter days. I'm not sure I understand what you mean by screwing with the hood/windshield aero and the engine temps are definitely cooler than with the OEM 135 Cowl.

[dbronnik]

Originally Posted by rhodesman

Could you elaborate on this? I did the M3 Cowl conversion and saw a nice decrease in engine bay temps on hotter days. I'm not sure I understand what you mean by screwing with the hood/windshield aero and the engine temps are definitely cooler than with the OEM 135 Cowl.

+1, have been running them for a while now with no issues. I don't DD my 1er, but I have driven it in the rain without the cowl without any issues (although I do avoid driving it in the rain). I probably would have stuck with the cowl if I didn't live in California and DD my car though.

[ShocknAwe]

Originally Posted by rhodesman

Could you elaborate on this? I did the M3 Cowl conversion and saw a nice decrease in engine bay temps on hotter days. I'm not sure I understand what you mean by screwing with the hood/windshield aero and the engine temps are definitely cooler than with the OEM 135 Cowl.

Quantify decrease in engine bay temps on hotter days. How did you measure it. Were all days equal temp? Was this stopped or while driving? There are so many questions that would follow up a statement like that...

To answer your question:
The cowl and filter element helps create a lower pressure zone at the base of the windshield. This helps air flow over the windshield and hot air (should) flow out of the engine bay that way while the car is moving. If you remove it, air can flow back into the engine bay from the rear of the hood, ultimately air swirls at the base of the windshield, creating a high pressure zone, and hot air gets trapped in the engine bay.

Same reason that hood spacers are a dumb idea. Much less of an effect I would think than hood spacers though.

[Dylanize]

Originally Posted by ShocknAwe

To answer your question:
The cowl and filter element helps create a lower pressure zone at the base of the windshield. This helps air flow over the windshield and hot air (should) flow out of the engine bay that way while the car is moving. If you remove it, air can flow back into the engine bay from the rear of the hood, ultimately air swirls at the base of the windshield, creating a high pressure zone, and hot air gets trapped in the engine bay.

Same reason that hood spacers are a dumb idea. Much less of an effect I would think than hood spacers though.

This is correct.

[rhodesman]

Originally Posted by ShocknAwe

Quantify decrease in engine bay temps on hotter days. How did you measure it. Were all days equal temp? Was this stopped or while driving? There are so many questions that would follow up a statement like that...

To answer your question:
The cowl and filter element helps create a lower pressure zone at the base of the windshield. This helps air flow over the windshield and hot air (should) flow out of the engine bay that way while the car is moving. If you remove it, air can flow back into the engine bay from the rear of the hood, ultimately air swirls at the base of the windshield, creating a high pressure zone, and hot air gets trapped in the engine bay.

Same reason that hood spacers are a dumb idea. Much less of an effect I would think than hood spacers though.

Not trying to bash, just trying to learn. In regard to the temps, I was measuring oil and coolant temps throughout hot days ranging from 90-100*F. I would be driving and my goal at the time was to lower the oil temps so the JB4 stopped going into failsafe mode when the oil temps got too hot (on hot days). Since I have a convertible, it was very easy to stick my hand up onto the windshield and feel the hot air coming out of the engine bay in the middle vs the sides. And I confirmed that the M3 Cowl was producing more venting of hot air based on how it felt. This is also confirmed when idling on cooler days and the center of the windshield would fog for a second if the wind blew it right.

Wouldn't the air coming into the engine bay via the radiator cause a high pressure in the engine bay if the air cannot escape quickly enough? I also have some air scoops added to the intake which pushes in cool air onto my BMS DCI's. So that too is another air source which I assumed would be adding in the higher pressure engine bay. Furthermore, the IAT was dropped at higher speeds when doing the ram-air & M3 cowl due to the free flow of air going through the engine bay allowing the intakes to breath cooler air.

Now this is all just my personal experience and "science" to modding the engine bay dynamics. My goal was overall a cooler running engine, as of now, my engine (oil and coolant) are seeing a 25-35% drop in running temps. So I guess I'm just not sold on how closing off an exit port for the heat is going to help decrease the running temp of the engine. Seems to me that it will just allow the engine to breath in warmer air and thus will cause it to get hotter.

School me here, I'm not seeing how the stock cowl helped to either cool or vent the engine compartment.

[ShocknAwe]

I already answered your question, and I'm pretty sure it's already been debated here on 1addicts so I really don't feel like rehashing it. If you want more information on fluid dynamics with respect to air flow, pressure and temperature, I'm sure there are numerous very high quality textbooks or scholarly web resources out there which you would find informative.

One thing stands out to me though...

You're seeing a 25-35% drop in running temps? That would be like going from 240 (avg peak oil, degF) to 156-180 degrees. I have 2 things to say to this and I'm bowing out of this discussion afterwards because I'm just at a loss.

#1: Bullshit.

#2: that would be harmful to your engine. You wouldn't even be reaching optimal running temps (210+).

[rhodesman]

Originally Posted by ShocknAwe

I already answered your question, and I'm pretty sure it's already been debated here on 1addicts so I really don't feel like rehashing it. If you want more information on fluid dynamics with respect to air flow, pressure and temperature, I'm sure there are numerous very high quality textbooks or scholarly web resources out there which you would find informative.

One thing stands out to me though...

You're seeing a 25-35% drop in running temps? That would be like going from 240 (avg peak oil, degF) to 156-180 degrees. I have 2 things to say to this and I'm bowing out of this discussion afterwards because I'm just at a loss.

#1: Bullshit.

#2: that would be harmful to your engine. You wouldn't even be reaching optimal running temps (210+).

I'm not sure why, but you're being a total prick. I'm just trying to have an open conversation about this. I will admit, in my haste to leave work and pick up my kids from school I was quick in my calculations and calculated the before WOT running Oil temp with the after IDLE running Oil temp, my bad.

I re-ran the calculations and still came up with a 8-15% decrease in running temps. Now, one could argue that yes, other mods I had made to the car (like a new intercooler, the BMS Oil Cooler Valve, and the ram-scoops) run cooler but the problem I had originally was that while doing spirited runs, my car would get so hot (read: oil in excess of 290*F) that it was going into failsafe.

At the time, the easiest mod I could do was the cowl filters and so that's what I did first and noticed a significant drop in running temperature. However, I did not like how water was just freely dumping itself down into the engine bay and thus I did the M3 cowl conversion. But even after all the other mods, I have not experienced what you claim and so that's why I wanted to talk more about it, fluid dynamics and all.

Forums are supposed to be about open conversation and respectable debate, not a "you are wrong and I'm done talking to you about it". I did search and read through some other cowl conversations but no definitive, measurable information that backed up said claims were posted (unless I missed it). I'll be happy to do some runs one day with the M3 cowl and then throw on the OEM cowl and do the same runs while logging temps and (if possible) get some internal engine bay temps. But I'll only do it if you show me the same respect I'm trying to show you and if I'm wrong, fine, I'm wrong but at least we'll have proof one way or the other.

[Solo_M_Tech]

One can argue the benefits of the OE cowl and air flow dynamics. It's there for a reason.

However, one could also argue that the M3 cowl achieves the same effect, but with much less actual cowl surface area.

Another aspect of this, is GT cars( Almost EVERY single race series) and endurance cars use vented hoods and modified cowl panels to evacuate as much air out of the engine bay as possible. This aids in radiator and inter-cooler efficiency. By sealing off the back of the hood area, you create a high pressure zone under the hood, reducing the amount of air volume that can pass across the cooling surface of the radiator, and reducing it's efficiency. This is why the hood will lift at high speeds. There is a HUGE mass of air trapped in the engine bay that can't get out. Deleting the cowl gives that air somewhere to go. Now is it the best possible way, no. It has negative effects. But for a cheap solution that helps, it works just fine.

Here in Florida, every single 135i and 335i I've seen or worked on has a cowl delete and BMS filters.

I'm not an engineer, but I can see practical results from DIY mods.

[Dylanize]

Originally Posted by rhodesman

Could you elaborate on this? I did the M3 Cowl conversion and saw a nice decrease in engine bay temps on hotter days. I'm not sure I understand what you mean by screwing with the hood/windshield aero and the engine temps are definitely cooler than with the OEM 135 Cowl.

I don't know what you are debating, the M3 cowl is something completely different then the BMS cowl delete... You still have a seal at the back of your hood. The M3 cowl is not going to affect the airflow like completely removing the cowl.

[rhodesman]

Originally Posted by Dylanize

I don't know what you are debating, the M3 cowl is something completely different then the BMS cowl delete... You still have a seal at the back of your hood. The M3 cowl is not going to affect the airflow like completely removing the cowl.

True, the M3 cowl conversion is a good substitute to just removing the Cowl completely. I even ran the M3 cowl with the BMS filters for a while before I eventually just modified the M3 Filter housings to fit into the 1-series. At the very least, the M3 cowl provides the same OEM rain/debris protection as the standard OEM Cowl.

What I was questioning was this whole argument that modifying the OEM cowl by either deleting it or in some other way to allow air to vent up the back of the engine bay between the hood and windshield had a negative effect on the engine bay temperatures. I was arguing that in my experience with the car and driving it in the modded state it is in, that having something OTHER than the OEM cowl was better for running temps.

[mike@x-ph.com]

I have this mod on my car and although sometimes the air whoosh is too loud inside the car (also have DCI), it makes my life much easier since im always adjusting my JB4

Now that the bluetooth connect kit is out and i dont have to plug the USB cable every time, i would probably put the stock cover back

If you have a JB4 and are using the USB cable you will love this mod