Purpose of the rear vent?

N8dawg · 02-19-2011, 12:36 AM

Unlike the closed off fender vents, the rear vent is open. Makes me think there must be a purpose for this. Anyone know what it is/if there is one?

NYCMCBM3 · 02-19-2011, 12:43 AM

on the bumper?

Legion5 · 02-19-2011, 12:46 AM

the more air at escapes from the rear of the car, the lower the pressure under the car and therefore the greater the downforce.

That's why a porsche 917 looks like this:

Radiation Joe · 02-19-2011, 07:04 AM

^^^ LOL! Tripodwned ^^^

Radiation Joe · 02-19-2011, 07:06 AM

I think it serves multiple purposes.

Airflow cools the area around the mufflers.
High pressure under the car is vented to the low pressure area behind the car which helps reduce lift and drag (to some minor degree).

N8dawg · 02-19-2011, 01:48 PM

Quote:

Originally Posted by NycE93M3

on the bumper?

Yes

N8dawg · 02-19-2011, 01:49 PM

Quote:

Originally Posted by Radiation Joe

I think it serves multiple purposes.

Airflow cools the area around the mufflers.
High pressure under the car is vented to the low pressure area behind the car which helps reduce lift and drag (to some minor degree).

Does this mean that with a aftermarket exhaust with much smaller mufflers that it may be more aerodynamic? or would it make it worse?

piloto · 02-19-2011, 02:29 PM

Quote:

Originally Posted by N8dawg

Does this mean that with a aftermarket exhaust with much smaller mufflers that it may be more aerodynamic? or would it make it worse?

No. It's not a real diffusor. It's primary purpose is just to help vent heat from the exhaust. Radiation Joe's comment about lower air pressure is correct in theory, but the M3's rear bumper cover vent isn't a diffusor so it's not really designed to remove enough air from underneath the back of the car to create downforce (or reduce lift). So no, you're not going to gain any measurable aerodynamic advantage with a lower profile muffler back there.

02-19-2011, 12:36 AM	#1
N8dawg First Lieutenant 53 Rep 383 Posts Drives: 2008 E90 M3 Join Date: Oct 2009 Location: St Petersburg, Florida iTrader: (0)	Purpose of the rear vent? Unlike the closed off fender vents, the rear vent is open. Makes me think there must be a purpose for this. Anyone know what it is/if there is one?
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02-19-2011, 12:43 AM	#2
NYCMCBM3 Colonel 167 Rep 2,711 Posts Drives: 2012 MCB E92 M3 Join Date: Apr 2010 Location: South Ozone Park,NY iTrader: (13)	on the bumper? __________________ 2012 MCB///M3
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02-19-2011, 12:46 AM	#3
Legion5 Major 175 Rep 1,379 Posts Drives: e92 Join Date: Dec 2007 Location: USA iTrader: (12)	the more air at escapes from the rear of the car, the lower the pressure under the car and therefore the greater the downforce. That's why a porsche 917 looks like this: __________________ Clean cars are happy cars! CANON PHOTOGRAPHER
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02-19-2011, 07:04 AM	#4
Radiation Joe Veni Vidi Vici 89 Rep 2,750 Posts Drives: '11 JB/BBe-6sp-e90 Join Date: Jul 2008 Location: Macungie PA iTrader: (0) Garage List 2011 e90 M3-Sold [8.50] 2003 RS6 - Sold [0.00] 2009 e90 M3 - Gone [0.00] 2003 M3 SOLD [0.00] old 2002 [10.00]	^^^ LOL! Tripodwned ^^^ __________________ Dinan compliment of stuff plus PF rotors and RG63s. Enough for now. Why, yes. I am an abrasive bastard.
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02-19-2011, 07:06 AM	#5
Radiation Joe Veni Vidi Vici 89 Rep 2,750 Posts Drives: '11 JB/BBe-6sp-e90 Join Date: Jul 2008 Location: Macungie PA iTrader: (0) Garage List 2011 e90 M3-Sold [8.50] 2003 RS6 - Sold [0.00] 2009 e90 M3 - Gone [0.00] 2003 M3 SOLD [0.00] old 2002 [10.00]	I think it serves multiple purposes. Airflow cools the area around the mufflers. High pressure under the car is vented to the low pressure area behind the car which helps reduce lift and drag (to some minor degree). __________________ Dinan compliment of stuff plus PF rotors and RG63s. Enough for now. Why, yes. I am an abrasive bastard.
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