# Function of M3 coupe gills?



## CMOS (Oct 1, 2002)

I'm sure this has been asked before, but my search has turned up no posts about this.

What function, if any, do the gills on the M3 coupe serve?

I think I read someplace that they are purely aesthetic. But my dealer has told me that they provide a cooling function. 

Honestly, I think their location is a bit fishy (sorry, no pun intended) for cooling. Usually cooling intakes have scoops to capture air. Plus they are usually in front of (not on top of) something that needs to be cooled (like the brakes).


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## JPinTO (Dec 20, 2001)

No functionality... purely aesthetic.


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## Jetfire (Jun 20, 2002)

Porbably just cosmetic. You do, however, feel engine heat radiating out of them. That's about as functional as they'll ever get.


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## The HACK (Dec 19, 2001)

They provide cooling for engine electronics and the DSC units.

The E46 M3 engine gets so damn hot at the top of the operating RPMs that it will strip paint...Imagine what it'll do to wires and plastic components. The "gills" are not open to allow air to pass through, but the hole on the fenders allow for some cooling of the electronics behind the gills.


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## alee (Dec 19, 2001)

The HACK said:


> *They provide cooling for engine electronics and the DSC units.
> 
> The E46 M3 engine gets so damn hot at the top of the operating RPMs that it will strip paint...Imagine what it'll do to wires and plastic components. The "gills" are not open to allow air to pass through, but the hole on the fenders allow for some cooling of the electronics behind the gills. *


If they are functional, why would they be taped up on the test mules? :dunno:


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## Jetfire (Jun 20, 2002)

Interesting possibility. While they probably do dissipate heat, I doubt that it's significant and I surely don't think that BMW would rely on those gills to keep the engine and electronics from self-destructing. If they really do get that hot, a hood with louvers or a slightly raised cowl would do the trick with less fuss. But I'm not a BMW engineer. My explanation seems more plausible to me as a throwback to the gills on the 3.0 CSi and several cars before it.


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## PhilH (Jun 7, 2002)

> *Function of M3 coupe gills?*


bling


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## Guest (Jan 21, 2003)

Personally, I think it's to make making your own faux-M3 more difficult/expensive. To those so inclined, it was relatively easy to make a fake E36 M3.


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## Kaz (Dec 21, 2001)

Considering that those compartments are gasketed when the hood is closed, and the 'ebox' itself is sealed, even if the gills are open, I doubt it'd do much for cooling.

I know some older BMWs actually had cooling fans in the 'e-box.'


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## The HACK (Dec 19, 2001)

alee said:


> *If they are functional, why would they be taped up on the test mules? :dunno:
> 
> 
> 
> ...


They're not OPEN in the first place. There's no sheet metal behind the plastic gills, but the gills do not allow air to flow through at all.

I think the gills cool the engine electronics by induction, not airflow. But the "cooling" feature was what I read in one of the design documents for the E46 M3.


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## Jetfire (Jun 20, 2002)

The HACK said:


> *They're not OPEN in the first place. There's no sheet metal behind the plastic gills, but the gills do not allow air to flow through at all.
> 
> I think the gills cool the engine electronics by induction, not airflow. But the "cooling" feature was what I read in one of the design documents for the E46 M3. *


Well, you do feel heat radiating from them. But I still don't think they dissipate any necessary amount of heat. But who am I to argue against the design doc, unless the document in question was primarily marketing fodder?

And from a personal viewpoint, I thought they were seriously tacky at first. But I've grown to like them.


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## Kaz (Dec 21, 2001)

The HACK said:


> *They're not OPEN in the first place. There's no sheet metal behind the plastic gills, but the gills do not allow air to flow through at all.
> 
> I think the gills cool the engine electronics by induction, not airflow. But the "cooling" feature was what I read in one of the design documents for the E46 M3. *


Um, if there is no hole, no air is getting in or out.

And 'induction' implies airflow...

Technically, 'induction' refers to the entry of the air-fuel mixture into the combustion chamber, not just the sucking in of air into the intake tract.


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## The HACK (Dec 19, 2001)

Kaz said:


> *Um, if there is no hole, no air is getting in or out.
> 
> And 'induction' implies airflow...
> 
> Technically, 'induction' refers to the entry of the air-fuel mixture into the combustion chamber, not just the sucking in of air into the intake tract.  *


Um, I mean radiation?

But yeah, I've done some close inspection of the gills and they do not have any sort of opening at all. I don't know exactly how they function. :dunno:


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## Jetfire (Jun 20, 2002)

The HACK said:


> *Um, I mean radiation?
> 
> But yeah, I've done some close inspection of the gills and they do not have any sort of opening at all. I don't know exactly how they function. :dunno: *


Radiation/conduction do work, but again I doubt they'd dissipate much heat unless they were in direct contact with the engine. Think of a Pentium heatsink. :dunno: I say it's just a gimmick with enough tiny functionality to pass for "functional." I also didn't realize they were just plastic.


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## The HACK (Dec 19, 2001)

Jetfire said:


> *Radiation/conduction do work, but again I doubt they'd dissipate much heat unless they were in direct contact with the engine. Think of a Pentium heatsink. :dunno: I say it's just a gimmick with enough tiny functionality to pass for "functional." I also didn't realize they were just plastic.  *


Funny you should mention plastic...Plastic is a poor conductor of heat. I thought, if the gills *were* constructed to aide in cooling the engine electronics, it would make a lot more sense to make them out of aluminum. The fin shapes on the gill does make great heat sinks though.:dunno:


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## JPinTO (Dec 20, 2001)

This exact same conversation happened 2 years ago when the E46M3 came out. The "wishful thinking" functionality side vs the "reality" cosmetic side. 

What electronics does the M3 have that other E46's don't that requires super cooling?


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## The HACK (Dec 19, 2001)

JPinTO said:


> *This exact same conversation happened 2 years ago when the E46M3 came out. The "wishful thinking" functionality side vs the "reality" cosmetic side.
> 
> What electronics does the M3 have that other E46's don't that requires super cooling? *


Nothing. Keep in mind the M3 engine runs VERY very hot at 8,000 RPM. "Butthead" has stripped paint underneath the heat-shield to prove this.

And this is paint baked on under intense heat. The M3 engine actually generates enough heat to MELT this stuff.


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