BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

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      03-24-2012, 01:42 AM   #1
andrey_gta
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2008 BMW 128i  [0.00]
Does N55 catless mid pipe make sense for 128i?

The 135i guys are going wild for these due to their low cost and no cats. I searched and found no information about using 135 midpipes specifically.
Also forgive my inability to understand how a turbo exhaust makes things different.

n55 on left with no cats:

So using 135i mid pipe would require a 135i axel back

128i 1 piece, notice the cats.

Therefore, the N55 catless mids would make things interesting. Would this throw any CEL or codes??
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Last edited by andrey_gta; 03-24-2012 at 01:53 AM.
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      03-24-2012, 05:22 AM   #2
AirMech135i
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Cheaper and easier to just cut out the cats and weld in a straight pipe. Can be done by any exhaust shop.
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      03-24-2012, 12:54 PM   #3
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Quote:
Originally Posted by AirMech135i View Post
Cheaper and easier to just cut out the cats and weld in a straight pipe. Can be done by any exhaust shop.
I agree. However due to regulation in Canada it may be hard to find such a shop.

Also if the piping on the 135i N55 is wider(2.75in) than 128i(2.5in) than this is a modestly priced upgrade.

Keep in mind that for the minimal performance gains that the NA N52 in the 128i can achieve this may be an optimal choice for performance and price vs the Maddad midpipe or similar. This will open up axle back possibilities we only read about before.
Also this will allow you to change back to stock for emission testing and resale.
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128i Sport 6MT converted to Euro 130i spec, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE
In-progress: n54 ssk, m3 trans mnt, e36M lip Wishlist: m3 susp, n55 eng mnt, headers, LSD, finn dif e60


"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is

Last edited by andrey_gta; 03-24-2012 at 05:07 PM. Reason: exhaust measure
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      03-24-2012, 05:18 PM   #4
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There's just not enough power to be gained from trying to open up the exhaust on a 128i - short of higher-performance cams, headers, a completely different induction system (individual throttle bodies like E46 M3), and other significant modifications, there's just not really anything you can bolt on that will make a significant difference other than a supercharger. Trade the 128 for a 135 and you have all sorts of easy tuning possibilities.
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      03-28-2012, 07:47 AM   #5
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With respect to codes, it depends on where the O2 sensors are. I have not researched my bimmer so I only know generalities. Modern engines have two O2 sensors that are before and after the catalytic converters. They both are looking to see if the air to fuel ratio is correct but the one after the catalytics also judges the converter's condition. If there is a O2 sensor bung behind the catalytic you remove and you thus remove the O2 sensor, that will throw a code. Even if you add the O2 sensor back, I would expect some codes because your exhaust without the converter will not look the same as it would with the converter. If the O2 sensors are all upstream of what you remove, there should be no codes.

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      03-28-2012, 12:21 PM   #6
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I do not think there is a second set of sensors. Other 135i exhausts offer cat less pipe and I have not seen a mention of sensors.
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128i Sport 6MT converted to Euro 130i spec, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE
In-progress: n54 ssk, m3 trans mnt, e36M lip Wishlist: m3 susp, n55 eng mnt, headers, LSD, finn dif e60


"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is
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      03-28-2012, 06:25 PM   #7
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Yep I believe that's correct. If these are the secondary cats there's no sensors after them in the exhaust. As Jim said, they're in the manifold and the first set of cats (just after the manifold).
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      03-29-2012, 09:44 AM   #8
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you will get a nice sound on the overrun... as for power, don't expect anything.
however you will save about 15lbs of curb weight, which is nice...
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