Anyone feel a difference with an aftermarket exhaust?

Edman951 · 01-04-2009, 12:07 AM

BimmerRob08,
It's like J08M3 said.
MAP sensor (Manifold Absolute Pressure)
MAF sensor (Mass AirFlow)

The S65 V8 M3 uses a MAP sensor.

If you wanna learn more on these sensors readup on them on Wikipedia.
http://en.wikipedia.org/wiki/MAP_sensor
http://en.wikipedia.org/wiki/Mass_flow_sensor

Map sensors don't see changes in engine volumetric efficiency as well as MAF.
Since BMW tuned the DME according to it's factory tested % of engine volumetric efficiency, with required values to make there performance requirements.

Now adding a few extra % of volumetric efficiency on a engine from a exhaust and air filter. The DME doesn't see them as well with a MAP sensor and cannot adjust the fuel for optimum performance.
But the engine has safeties built in so you don't damage the motor from leaning out.
By using the integrated 8 knock sensors and 4 O2 sensors.

Now this is what i know, but i don't know all the DME functions and tune. As i'm no tuner.
Maybe tuners on here will clear some of this up.

BimmerRob08 · 01-04-2009, 03:42 PM

Sweet!! Clear as mud! Thanks for clearing that up a bit. So basically the programed ECU OEM settings, is tuned to the air intake and exhaust. By changing these two variables, inlet & exhaust, the ECU must recalculate the changed perameters but both of the modifications people do are still well within the limits of the ECU I take it?

ebohon · 01-05-2009, 12:27 AM

Good info... does anyone know if the ECU will then adjust automatically after driving a while with a new filter and / or exhaust to the new volume efficiency or is a reflash really the only way to take advantage of these bolt-on mods?

RDSport · 01-05-2009, 02:36 AM

It has been our experience that if you design a rear silencer (or silencers) that use too big a section, the loss of back pressure results in a substantial loss of low-end and mid-range torque, with no benefit in the higher RPM range. In fact, the impression you are getting when you feel the car pull harder up top, may very well be that you have lost quite a bit below and your car just feels quicker when, in fact, it is no quicker than stock. A before and after dyno run should be able to confirm this for you.

Mischievous M · 01-05-2009, 10:29 AM

Quote:

Originally Posted by MrHarris

I got a Remus race, and sometimes I feel as if my car may actually be slower. A friend of mine said my car doesn't accelerate as violently as before. Anyone else feel a difference with their aftermarket exhaust? Good or bad.

I'm running a Vorsteiner Titanium exhaust currently and I can vouch that I have definitely got a leap of gains in the overall feel of the car throughout the power band.

Waiting to fit my X-pipes by AA on my ride tomorrow so I should expect to free up a lil more in my baby. let you know soon

William Blake · 01-05-2009, 11:33 AM

Quote:

Originally Posted by RDSport

It has been our experience that if you design a rear silencer (or silencers) that use too big a section, the loss of back pressure results in a substantial loss of low-end and mid-range torque, with no benefit in the higher RPM range. In fact, the impression you are getting when you feel the car pull harder up top, may very well be that you have lost quite a bit below and your car just feels quicker when, in fact, it is no quicker than stock. A before and after dyno run should be able to confirm this for you.

Yes but I'm sure the Remus/AC S exhaust are very well engineered right?

Changing only the rear mufflers doesn't really do much does it? (I mean it's 'safe')

jlaw · 01-05-2009, 08:24 PM

Just because the S65 uses a MAP sensor does not mean that it will run poorly/worse than stock if modified within reason. With things like intake and exhaust, the ECU will see a deviation in the LTFT and adjust fueling accordingly.

Ronin13 · 01-05-2009, 09:59 PM

Quote:

Originally Posted by William Blake

Leave that intake system OEM. AFE does nothing (or worsens it)

I would agree that a replacement filter would be close to zero on an EU car. The US cars are stuck with the charcoal layer built in their filters so there is a small gain. AA's dyno for their paper replacement, which looks a lot like a stock EU filter, was showing 5-7 hp differences over the US stock version.

William Blake · 01-06-2009, 03:07 AM

Didn't know there was a difference in the EU-spec airbox vs US-spec airbox

jlaw · 01-06-2009, 09:36 AM

I believe the airboxes are identical; the filter element is different for US cars due to emissions requirements.

MrHarris · 01-06-2009, 05:17 PM

So, does anyone else feel a power/torque loss from about 2k rpm-3k rpm? I actually find it pretty noticeable in acceleration going up a slight incline in 2nd or 3rd gear.

jlaw · 01-06-2009, 05:20 PM

I think it's in your head

MrHarris · 01-06-2009, 06:03 PM

Quote:

Originally Posted by jlaw

I think it's in your head

I hope so

NinetyEight740 · 01-06-2009, 10:54 PM

As we all know, the butt dyno dosent lie, and of course if your car sounds faster it IS faster

01-04-2009, 12:07 AM	#23
Edman951 Second Lieutenant 50 Rep 287 Posts Drives: 2014 i3, Capparis White Join Date: Nov 2006 Location: Montreal, Quebec iTrader: (1)	BimmerRob08, It's like J08M3 said. MAP sensor (Manifold Absolute Pressure) MAF sensor (Mass AirFlow) The S65 V8 M3 uses a MAP sensor. If you wanna learn more on these sensors readup on them on Wikipedia. http://en.wikipedia.org/wiki/MAP_sensor http://en.wikipedia.org/wiki/Mass_flow_sensor Map sensors don't see changes in engine volumetric efficiency as well as MAF. Since BMW tuned the DME according to it's factory tested % of engine volumetric efficiency, with required values to make there performance requirements. Now adding a few extra % of volumetric efficiency on a engine from a exhaust and air filter. The DME doesn't see them as well with a MAP sensor and cannot adjust the fuel for optimum performance. But the engine has safeties built in so you don't damage the motor from leaning out. By using the integrated 8 knock sensors and 4 O2 sensors. Now this is what i know, but i don't know all the DME functions and tune. As i'm no tuner. Maybe tuners on here will clear some of this up. Attached Images
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01-04-2009, 03:42 PM	#24
BimmerRob08 Major 110 Rep 1,311 Posts Drives: 2008 M3, Space Gray Join Date: Mar 2008 Location: KIKR (ABQ), NM iTrader: (0)	Sweet!! Clear as mud! Thanks for clearing that up a bit. So basically the programed ECU OEM settings, is tuned to the air intake and exhaust. By changing these two variables, inlet & exhaust, the ECU must recalculate the changed perameters but both of the modifications people do are still well within the limits of the ECU I take it?
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01-05-2009, 12:27 AM	#25
ebohon Second Lieutenant 15 Rep 255 Posts Drives: 2009 M3 Coupe, 6MT Join Date: Sep 2008 Location: Anaheim Hills, CA iTrader: (2)	Good info... does anyone know if the ECU will then adjust automatically after driving a while with a new filter and / or exhaust to the new volume efficiency or is a reflash really the only way to take advantage of these bolt-on mods? __________________ 2009 M3 : 6MT : Carbon : Silverstone : Fox Red Novilo : Aluminum Trim : Tech Package : iPod : MODS: Performance Spoiler: Clear Reflectors : H&Rs : Escort 9500ix hardwired : Tint : Macht Schnell Filter : RPI Scoops : Rogue Pulley : Fabspeed resonated x-pipe with Remus Race : ESS Tune: TVinMotion
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01-05-2009, 02:36 AM	#26
RDSport Private 9 Rep 62 Posts Drives: 2007 RS35 Biturbo Join Date: Mar 2007 Location: Laguna Niguel, CA iTrader: (0)	Another thought It has been our experience that if you design a rear silencer (or silencers) that use too big a section, the loss of back pressure results in a substantial loss of low-end and mid-range torque, with no benefit in the higher RPM range. In fact, the impression you are getting when you feel the car pull harder up top, may very well be that you have lost quite a bit below and your car just feels quicker when, in fact, it is no quicker than stock. A before and after dyno run should be able to confirm this for you.
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01-05-2009, 08:24 PM	#29
jlaw First Lieutenant 29 Rep 351 Posts Drives: F80 M3 Join Date: Aug 2007 Location: Miami, FL iTrader: (0)	Just because the S65 uses a MAP sensor does not mean that it will run poorly/worse than stock if modified within reason. With things like intake and exhaust, the ECU will see a deviation in the LTFT and adjust fueling accordingly.
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01-06-2009, 03:07 AM	#31
William Blake Private First Class 4 Rep 105 Posts Drives: 08 MINI Cooper S Clubman Join Date: Nov 2008 Location: Europe iTrader: (0)	Didn't know there was a difference in the EU-spec airbox vs US-spec airbox
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01-06-2009, 09:36 AM	#32
jlaw First Lieutenant 29 Rep 351 Posts Drives: F80 M3 Join Date: Aug 2007 Location: Miami, FL iTrader: (0)	I believe the airboxes are identical; the filter element is different for US cars due to emissions requirements.
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01-06-2009, 05:17 PM	#33
MrHarris yodog 197 Rep 5,026 Posts Drives: '86 Corolla Join Date: Jun 2007 Location: Diamond Bar, Ca iTrader: (5) Garage List 2009 BMW [10.00]	So, does anyone else feel a power/torque loss from about 2k rpm-3k rpm? I actually find it pretty noticeable in acceleration going up a slight incline in 2nd or 3rd gear. __________________ 2009 E92 M3 \| Alpine White \| Black Extended \| Advan RS \| Turner Test Pipes \| Dinan Axle-Back \| OETuning \| Eibach Springs \| UUC SSK \| VRS Front Lip \| VRS Type I Diffuser \| Matte Black \| RPi Scoops \| MS Filter \| Yokohama AD08 \| F1 Pinnacle Special Thanks: Gintani \| OETuning \| eAs
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01-06-2009, 05:20 PM	#34
jlaw First Lieutenant 29 Rep 351 Posts Drives: F80 M3 Join Date: Aug 2007 Location: Miami, FL iTrader: (0)	I think it's in your head
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01-06-2009, 10:54 PM	#36
NinetyEight740 Major General 231 Rep 5,691 Posts Drives: 2 - 2013 535i msport Join Date: Nov 2008 Location: Orange County California iTrader: (2) Garage List 2010 E91 [0.00]	As we all know, the butt dyno dosent lie, and of course if your car sounds faster it IS faster
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