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F30 / F31 / F32 / F33 / F36 (2012 - current)
The sixth generation 3 series, chassis code F30. 2013 model year 328i and 335i sedans now in production. Read the F30 frequently asked question thread for all your basic question and dive into all the details in the ultimate F30 information thread.

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  #1  
Old 09-30-2012, 09:44 PM
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CALWATERBOY CALWATERBOY is offline
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F30 Exhaust Flap Disabled?

Chipped or not, find my N54 smoother w/more torque off the line with driver side exhaust flap line crimped. Really, big improvement.

So, gotta wonder: Does N20 respond the same? Found a few like this but didn't see whether feel is improved like N54. Gut says it should....

You F30 owners - who's got info?

.

Last edited by CALWATERBOY; 09-30-2012 at 09:59 PM.
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  #2  
Old 10-02-2012, 10:15 AM
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CALWATERBOY CALWATERBOY is offline
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Baby-bump....

Nobody's done this simple mod? Easier than crimping a vac line, just remove a clip.

N54 effect w/Step :
  • Smoother pickup from stop
  • Higher low end torque
  • Smoother re-engagement, N to D while/after coasting
  • Much more modulatable throttle, low
  • Louder low end
  • Less to no brake bob, coming to a stop

Evidently better breathing's a good thing.


How 'bout you N20 pilots?


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Last edited by CALWATERBOY; 10-02-2012 at 11:15 PM.
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  #3  
Old 10-06-2012, 10:33 PM
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Quote:
Originally Posted by CALWATERBOY View Post
Chipped or not, find my N54 smoother w/more torque off the line with driver side exhaust flap line crimped. Really, big improvement.

So, gotta wonder: Does N20 respond the same? Found a few like this but didn't see whether feel is improved like N54. Gut says it should....

You F30 owners - who's got info?

.


Sorry, your crimp mod did not create any noticeable torque increase. Complete placebo effect.
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  #4  
Old 10-06-2012, 10:37 PM
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justinnum1 justinnum1 is offline
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Golf tee mod does nothing but increase sound from the exhaust, and some people say it makes a difference, others say it doesnt. I dont think it does anything for the n20
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  #5  
Old 10-07-2012, 12:12 AM
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CALWATERBOY CALWATERBOY is offline
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Originally Posted by justinnum1 View Post
Golf tee mod does nothing but increase sound from the exhaust, and some people say it makes a difference, others say it doesnt. I dont think it does anything for the n20
Reducing exhaust area 50% has an effect vs flap open. Perceived add'l torque off idle may be no more than faster turbo spin-up due to reduced back pressure.

Anyone got a readout on that?
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Old 10-07-2012, 09:21 AM
Elk Elk is offline
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Originally Posted by CALWATERBOY View Post
Reducing exhaust area 50% has an effect vs flap open.
Only if during the time the flap is normally closed, the engine is being held back by the failure of sufficient air to move through the exhaust. This is not the case.

Even a full exhaust replacement makes relatively little difference in HP and torque on this engine, perhaps 3%. Accordingly, a tiny mod which effects only part of the exhaust in during a limited RPM range is doing nothing.

Besides, if power was this easy to generate and the only downside is a slightly louder engine, don't you think someone at BMW would have thought of this? It takes a untrained, backyard mechanic to figure this out?

The perceived change is purely emotional - "it's a tad louder and I made a change. Therefore there must be more power."

Expectation bias is vastly more powerful than this exhaust mod.
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  #7  
Old 10-07-2012, 05:31 PM
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Originally Posted by Elk View Post
Only if during the time the flap is normally closed, the engine is being held back by the failure of sufficient air to move through the exhaust. This is not the case.

Even a full exhaust replacement makes relatively little difference in HP and torque on this engine, perhaps 3%. Accordingly, a tiny mod which effects only part of the exhaust in during a limited RPM range is doing nothing.

Besides, if power was this easy to generate and the only downside is a slightly louder engine, don't you think someone at BMW would have thought of this? It takes a untrained, backyard mechanic to figure this out?

The perceived change is purely emotional - "it's a tad louder and I made a change. Therefore there must be more power."

Expectation bias is vastly more powerful than this exhaust mod.

There's a boost, smoothness & torque, beyond doubt - it's movement off-idle I'm talking about.

Power is that easy to generate all other things being equal. Yup, it was shadetree guys who tried & liked it. Popular thought's that noise regs created the flap, tho emission volume [not %] may have played a part.

Hey, try it. If you no like, easy enough t'return to stock. Looking for map specific settings so's can snip the wire tie....

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  #8  
Old 10-07-2012, 06:50 PM
Elk Elk is offline
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Originally Posted by CALWATERBOY View Post
There's a boost, smoothness & torque, beyond doubt - it's movement off-idle I'm talking about.
I appreciate that you believe this. Expectation bias is exceedingly powerful.

Engine engineers will sell their first-born for a 1HP increase. They make many minute changes to engine design for much less than this. If removing the flap increased power to this degree it would not be there.

The 3% improvement realized with a full cat-back is difficult to feel as seat of the pants. But, it's louder so the driver thinks he feels more power. Even on a dyno one has to be careful to control all variables (heat soak, etc.) to even accurately measure a difference.

Let's assume the flap-mod produces a full ten percent of a cat-back - a very generous estimate. You honestly believe one can truly and accurately feel a 1-2 HP increase in a 250hp-300hp engine?

Enjoy the mod if you like the sound. Don't fool yourself into thinking you have a perceivable, or even fractionally measurable, increase in power.

Then there is the magic spark plugs, special magnets, EMI/RFI filters, special power producing oil additives . . . in no time an F30 can produce 400hp - 500hp. Easy.
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  #9  
Old 10-07-2012, 11:47 PM
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Might have to reverse on this....flap open / lower back pressure may reduce torque, but result in a more controllable throttle at low rpm. Interesting.
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Old 10-11-2012, 11:52 PM
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CALWATERBOY CALWATERBOY is offline
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Originally Posted by CALWATERBOY View Post
Might have to reverse on this....flap open / lower back pressure may reduce torque, but result in a more controllable throttle at low rpm. Interesting.
This.

Frankly I'm liking the volume, but prefer a mellower tone. Taking what I can get.

Should play w/JB4....sadly, way too busy. Maybe Nov.
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