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Sport Exhaust System - How Does It Work

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Old 03-25-2020, 09:22 AM
  #16  
LexVan
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Originally Posted by Jim M.
The system is activated by the switch on the consul. This switch activates via the vacuum system to two valves in the exhaust pathway that redirects the exhaust more directly out the tail pipe. No Your picture still does NOTHING to show how easily extra fuel is added. Yes extra fuel is added through the DME but the majority of the sound increase is due to the vacuum controlled valves, not the extra fuel that is added.
Jim, you are describing how the PSE turns on (goes into the loud mode). This has nothing to do with the over-runs produced by the DME over fueling when the exhaust valve is open for the snaps, crackles & pops. That's why I posted that picture. In that picture the exhaust valve is closed, but you can easily visualize how the DME can tell the fuel injector to give an infinitesimal squirt of fuel (negligible effect on MPGs) when the exhaust value is open, for the induced sound effects.
Old 03-25-2020, 10:51 AM
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Jim M.
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The OP's question was "Sport Exhaust System - How Does It Work." Everyone, including you, did not answer his question but just talked about the added fuel that causes the pops and gurgles during overrun. Your picture shows what happens during every revolution of every cylinder during normal running.
Old 03-25-2020, 11:09 AM
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LexVan
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Originally Posted by Jim M.
The OP's question was "Sport Exhaust System - How Does It Work." Everyone, including you, did not answer his question but just talked about the added fuel that causes the pops and gurgles during overrun. Your picture shows what happens during every revolution of every cylinder during normal running.
You sound stressed out, Jim, sorry you are having such a bad morning. Hope this helps and your day improves:


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Old 03-25-2020, 12:01 PM
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Carlo_Carrera
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Originally Posted by Jim M.
The OP's question was "Sport Exhaust System - How Does It Work." Everyone, including you, did not answer his question but just talked about the added fuel that causes the pops and gurgles during overrun. Your picture shows what happens during every revolution of every cylinder during normal running.
You should really re-read the first post. He specifically asked about the "gurgling" which is done via fuel injection off throttle. - -"I recall reading somewhere that fuel was being sprayed on some hot bit,"


Old 03-25-2020, 02:52 PM
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rnl
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this may help
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0036_200325135153_001.pdf (1.34 MB, 209 views)
Old 04-04-2020, 08:39 PM
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DenVogel
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Thanks rnl. This is the kind of thing I was looking for. I appreciate you taking time to post it.
Old 04-06-2020, 08:43 PM
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rnl
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Originally Posted by DenVogel
Thanks rnl. This is the kind of thing I was looking for. I appreciate you taking time to post it.
my pleasure!
Old 04-07-2020, 11:36 PM
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BSO
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In older manual transmission cars/motorcycles you could get some serious backfire by switching the ignition off during deceleration and turning it back on.

Unburned fuel/air mixture reaches the hot exhaust, detonates, causing the backfire.

I suspect this is how the pops/crackles are currently produced.

Last edited by BSO; 04-09-2020 at 01:53 PM.
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Old 04-09-2020, 12:09 PM
  #24  
quattroboy
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Its interesting in the service manual, it states "on the sports exhaust system, activating the exhaust flaps also reduces the exhaust back pressure (for a sporty sound and improved torque curve)..."

I wonder if there is any documented measurements that show difference in the torque curve as I was always under the impression that the sport exhaust did not increase performance.
Old 04-09-2020, 02:58 PM
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fnckr
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According to the tech manual posted before, it does that on the regular exhaust for the S cars too.



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