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Exhaust mod in N55 E92 after DP
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04-06-2014, 08:29 AM | #1 |
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Exhaust mod in N55 E92 after DP
What are the performance gains between muffler mod vs cat back vs axle back vs stock with golf tee mod in a car with cattless DP???
The stock E92 2.25" x 2 piping has little resistance and I'd hate to spend $1,200~2,500 on exhaust, get only 2whp and have pull me over/ricer loud exhaust. I know I'm asking a lot, but it would help people figure out the utility/value of an exhaust mod or upgrade…
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04-06-2014, 01:29 PM | #3 |
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I had a Pro turner in my area tell me it was worth slapping a high flow system on before having him dyno & tune the car… I doubt he has seen the exhaust setup on the N55 e92, but I wanted to see what the consensus was.
I agree that gains are likely trivial.
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Wagner EVO II C | Akarpovic SS Evolution Exhaust | Cp-e DPs | Koni | CV5F Forgestar et 32/38 on 255/35/19 & 275/35/19 | DW400 | Swift spec R | N20 sensor | PB Valve Cover | GCL | M3 control arms | JE forged piston kit | Carillo forged rods | Ported Head | F80 DMFW |
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04-06-2014, 07:03 PM | #4 |
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I'm curious also if anyone else can chime in on these gains or lack thereof. More out of curiosity than anything. While DP are guranted for me I've been toying with the idea of the VRSF catback exhaust.
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04-08-2014, 10:22 PM | #6 | |
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I searched for more specific data (actually dyno #'s results) to no avail. Please let me know or post the URL if you find any dyno results comparing e92 N55 with cattless DP stock exhaust (or golf tee mod) to upgraded exhaust…
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Wagner EVO II C | Akarpovic SS Evolution Exhaust | Cp-e DPs | Koni | CV5F Forgestar et 32/38 on 255/35/19 & 275/35/19 | DW400 | Swift spec R | N20 sensor | PB Valve Cover | GCL | M3 control arms | JE forged piston kit | Carillo forged rods | Ported Head | F80 DMFW Last edited by MNick; 04-08-2014 at 10:26 PM.. Reason: reduce redundancy |
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04-08-2014, 10:43 PM | #7 |
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That's because nobody wants to pay money to throw their car on the dyno twice, just to see the same numbers each time.
Let me just throw up a disclaimer before I break it down for you: I am not an engineer; nor have I ever aspired to become one. I am also not a BMW guru; just an enthusiast. That being said - the reason that you see noticeable gains when replacing the downpipe, is that you are removing a restrictive catalytic converter. Doing so, allows the exhaust to flow much more freely - thus the gains. When replacing the already free-flowing stock catback, with and equally (slightly more) free-flowing aftermarket catback - you are not really removing anything restrictive. Hence, you will see negligible gains. Last edited by Sidewinderpb; 04-08-2014 at 10:59 PM.. |
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04-09-2014, 07:21 AM | #8 | |
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I figured I was asking a lot to see data, I certainly don't want to pay for research (multiple dyno runs).
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04-09-2014, 08:31 AM | #9 | |
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I also believe that the stock piping is already 2.5". |
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04-18-2014, 07:53 AM | #10 |
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Yeah I measured it a while ago looked like 2.25" but you might be right.
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Wagner EVO II C | Akarpovic SS Evolution Exhaust | Cp-e DPs | Koni | CV5F Forgestar et 32/38 on 255/35/19 & 275/35/19 | DW400 | Swift spec R | N20 sensor | PB Valve Cover | GCL | M3 control arms | JE forged piston kit | Carillo forged rods | Ported Head | F80 DMFW |
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04-18-2014, 07:57 AM | #11 |
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Let me guess, he is the one selling it to you?
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04-21-2014, 08:05 PM | #12 |
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LOL! I was waiting for it, but he did not try to sell one to me (don't think they stock them)... He did talk me into stopping by the shop later this week to see the single turbo upgrade they r putting into a N54, hope to see it on the Dyno... More interested in this than an exhaust.
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04-21-2014, 10:36 PM | #13 |
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I think the biggest restraint is from the turbo. If the outlet is 3 inches what good would it be to have anything larger. Behind the turbo? You might lose back pressure and power. I'd stick with stock unless we run bigger outlet turbos. Of course you might want the benefit of sound which has it's perks!
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04-22-2014, 08:07 AM | #14 | |
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04-22-2014, 01:45 PM | #15 |
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based on the options you gave I'm gunna have to say very small gains from all options except the dp which i believe has some decent gain?
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04-22-2014, 03:02 PM | #16 | |
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In forced induction engines, exhaust gasses are just that. Contrast with natural aspiration, wherein a certain amount of backpressure is beneficial (I don't know more than that, I've always had a turbo'd engine). The premier method of getting rid of exhaust gasses? I'm glad you asked: Any piping just creates drag that slows down your turbine. Larger piping creates less drag; straighter piping creates less drag; etc. |
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