What is fascination with N55 down pipe.

[nachob]

Dear einsers. What is the fascination with N55 down pipe? Less restriction? Sound? Documented power or torque gains? I have worked in a dyno before and horsepower gains never come as easily as most people think so I'm curious? A lot goes into designing exhaust systems including a certain amount of back pressure so I'm shocked that a down pipe designed for a single larger turbo would work better for two smaller ones. can someone fill me in on the reason for this common swap and does anyone have calibrated dyno data before and after. I am leaving my mind open!! Thank you

[ayao]

Less drone (fake N54 DP resonator) with possible modest HP gain from less back pressure. More burble and stock appearance.

[Dackelone]

I actually thought I lost HP down low(under 4K rpms) with my N55 mids on my N54.

The reason I went with he N55 mids bc I wanted a deeper throatier exhaust sound. What I got was just more volume and some rasp/drone at cruising. I then threw back on my N54 mid pipe with secondary cats and went with the full PE(performance exhaust)... I could not be any happier!

Looking back I wasted $400 on that N55 mid pipe. I should have just bought a PE in the first place.

[nachob]

Originally Posted by Dackelone

I actually thought I lost HP down low(under 4K rpms) with my N55 mids on my N54.

The reason I went with he N55 mids bc I wanted a deeper throatier exhaust sound. What I got was just more volume and some rasp/drone at cruising. I then threw back on my N54 mid pipe with secondary cats and went with the full PE(performance exhaust)... I could not be any happier!

Looking back I wasted $400 on that N55 mid pipe. I should have just bought a PE in the first place.

That was my concern....engineers allow for some back pressure which helps at lower rpms so you might in fact gain some horsepower at high end but lose some power/torque or response at lower rpms. I worked in the dyno for a factory GTP team and our needs where for more race situations then street which is why I was asking. The N55 was already in production when the 1M came out and ///M took parts from different cars to make the 1M. They took E90 M3 suspension, brakes, rear drivetrain and mirrors and 335is motor. they had access to N55 midpipe at the time but chose not to use it and instead went with the one on it so there was some thought process going on.

Dackel, which PE are you referring to? Did BMW performance make one for 1M? I only knew of M3 PE.

Thank you.

IB

[nachob]

Originally Posted by ayao

Less drone (fake N54 DP resonator) with possible modest HP gain from less back pressure. More burble and stock appearance.

I wish I could hear it!!! When you coming to San Diego?

I actually miss the drone...my Canadian VO doesn't drone like my US spec white one...I miss the sound!

[Dackelone]

Originally Posted by nachob

That was my concern....engineers allow for some back pressure which helps at lower rpms so you might in fact gain some horsepower at high end but lose some power/torque or response at lower rpms. I worked in the dyno for a factory GTP team and our needs where for more race situations then street which is why I was asking. The N55 was already in production when the 1M came out and ///M took parts from different cars to make the 1M. They took E90 M3 suspension, brakes, rear drivetrain and mirrors and 335is motor. they had access to N55 midpipe at the time but chose not to use it and instead went with the one on it so there was some thought process going on.

Dackel, which PE are you referring to? Did BMW performance make one for 1M? I only knew of M3 PE.

Thank you.

IB

I was referring to the PE for my N54, 135i.

I think maybe one reason ///M decided not to use the N55 mids was because they could not for emissions purposes.

But the 1M's rear resonator on the mid pipe is a "dummy" one. Even though the 1M is a N54 engine... some things are different from the 135i(N54) like the down pipes have higher flowing cats and the mid pipe has a "dummy" rear resonator. A friend of mine cut one apart and found this...

found out something interesting about the 1M exhaust...
http://www.1addicts.com/forums/showthread.php?t=779462

[mikewills]

Get the maddad midpipe.

[wjk_glynn]

Originally Posted by nachob

...Dackel, which PE are you referring to?

Here's a link to it on BMW's accessories site: http://www.shopbmwusa.com/PRODUCT/33...EXHAUST-SYSTEM

Karl.

[rad doc]

I am real confused. The op was asking about n55 downpipes. I have never heard of using n55 dp's. The n55 mid is a nice upgrade if you want to stay with oem parts. Otw, the maddad is the way to go. Great upgrade.

[BMW135pls]

Originally Posted by Dackelone

I actually thought I lost HP down low(under 4K rpms) with my N55 mids on my N54.

You definitely do, this is what I experienced when I went from OE N54 to 3" DP. Much better high end power that carries closer to redline though, so that's the tradeoff.

[ALEJANDRO]

the maddad is the way to go if you have the stock catback. if you have something like akra or hms, n55 would be a better combination. mad dad plus any of these aftermarket exhausts might be way too loud.

[nachob]

Any San Diego guys with it? Would love to hear the mad dad or n55

[bdaddylo]

The benefits to going to any midpipe deleting the secondary cats on the 1m are as follows:

1. More mid and upper rpm range torque. Mostly in the mid range, but you won't lose anything down low. Turbos hate back pressure.

2. More sound from the exhaust.

3. Reduced or eliminated drone that was caused by the fake resonator on the 1M midpipe.

Midpipe options are as follows:

1. N55

2. Berk

3. Maddad

The aftermarket midpipes will provide the best performance due to larger diameter pipes as well as less drastic bends.

[ALEJANDRO]

Originally Posted by nachob

Any San Diego guys with it? Would love to hear the mad dad or n55

there is video somewhere where to guys with hms exhausts make the comparison

[redux]

Why not check out the Akrapovic? I've seen a used full system sell for around $1500. Yes its a big jump in price from a mid-pipe, but if this car is keeper....... Why not?

[1&done]

Originally people were complaining of drone in the 1M because of the dummy resonator. (in place likely to trick officials as the 1M was fast tracked and alterations to its exhaust would have required more testing...Al Gore bs stuff)

I am sorry, having 4 cats is way too restrictive, I am running AR Ceramic coated Catless DPs, N55 mids, BMWP Y-pipe in place vs resonator and Dinan exhaust....car is LOUD! But sounds like nothing I have heard before...Especially under WOT. Did gain HP, however, adding catted DPs will yield higher trq #s.

The stock 1M DPs do have somewhat higher flowing cats, based on what I have read and seen, but, they are sub-par if you plan to turn up the fun factor w/ a tune.

[nachob]

Originally Posted by redux

Why not check out the Akrapovic? I've seen a used full system sell for around $1500. Yes its a big jump in price from a mid-pipe, but if this car is keeper....... Why not?

I'm pretty happy with stock sound for the most part just trying to figure out what the DP thing was all about. some do it for sound, some for power, etc. I never see 1Ms here in San Diego but I will start paying attention next time I see one with Akra or DP swaps to see what they sound like and who who knows?

[redux]

You can check my car out if you are ever in Costa Mesa. It just sits in the corner of my friend's shop while I'm aboard.

[nachob]

Originally Posted by redux

You can check my car out if you are ever in Costa Mesa. It just sits in the corner of my friend's shop while I'm aboard.

Thanks. I just had a pm that brought up another question. What about California smog test. Do you guys take them off for the test or will it pass?

[craina]

An N55 down pipe would not fit our cars. I believe you are thinking of the mid pipe which is a fairly inexpensive, quick to install OEM "upgrade" as others have pointed out. I installed an N55 mid pipe and it definitely woke up the exhaust note a little and throttle response was improved. Downside would be more exhaust soot on the tail pipes.

[redux]

Originally Posted by nachob

Thanks. I just had a pm that brought up another question. What about California smog test. Do you guys take them off for the test or will it pass?

I left the primary cats on because I didn't want to deal with the smoke test bs when the car has to get the sniffer in two years. The N55 mid-pipe won't have an issue with smog either (the N55 down pipe wont fit on our cars; single vs twin turbo).

[EldRick]

I bought Dac's N55 resonator y-pipe to replace the stock fake resonator y-pipe, and found that initially it cut the resonance noise-level somewhat, and that over the next few thousand miles it became more effective, getting rid of maybe 2/3 of the resonant noise peak at 2300 and 2800 rpm.
Performance difference? Not apparent to my butt-dyno, and I wouldn't expect a change, as the perforated y-pipe inside is the same diameter as the stock 1M pipe.