Running full "straight pipes" ??

Chenry135 · 02-12-2010, 02:15 PM

I have a custom exhaust on mine that is just a 3 1/2 inch pipe all the way back. No resonators or mufflers. It's pretty loud, but nothing extreme. I don't have DP's though so i guess that's why...

ar design · 02-13-2010, 11:11 AM

I had straight pipes on the 3. LOUD.

dyong · 02-21-2010, 11:50 AM

Quote:

Originally Posted by onefastman

Very good to know, I have 2.5" dp's and 3" RR mid pipe so I would stay with the 3". I just need to know what I should look to pay for an axle back.

Also for autocross could I get away with taking the muffler off and running just dp's and mid pipe. Would it be too loud?

Does your RR mid pipe fit with the stock resonator/muffler? How does it sound like? I thought of going catless but retaining the stock muffler. Thanks.

6spdMSport · 02-23-2010, 11:12 PM

Iam now running straight pipes, i have VK catless downpipes with a custom cat-back by miami mufflers. no mufflers, 2 2.5's into a single 3. its loud but i like it its worth it.

evifytrihteno · 04-08-2010, 08:13 PM

I have 3" Catless Downpipes on my 1. I want full straight pipes for the rest of my exhaust (currently stock cat-back).

Is there a pre-fabbed exhaust on the market that is 3" all the way to the back without a muffler?

Thanks

onefastman · 04-08-2010, 10:27 PM

I am assuming that they are Ar or something to that effect. If that is the case then they are not actually 3", they start at 3 and taper to 2.5" to fit the exhausts made. Depending on your budgit (assuming you have some $ to spend) I would go with any catless mid pipe and a eissimann muffler (or meisterschaft). It will perform (not that the secondary cats do much) and sounds better than any system on the market.

bmore135 · 04-09-2010, 04:21 PM

here is my vid... vk catless downpipes, Y to a 3" pipe, 1 high flow straight through resonator, and just tips. no muffler no cats...

igom3 · 04-09-2010, 06:14 PM

Quote:

Originally Posted by Brahmzy

Keep in mind the bigger the diameter, is not necessarily the better, depending on power output.
Yes it's true we want absolutely zero backpressure, however, you can still go "too big" on your piping, especially using stock trubos.

The point in a turbo-charged car is to get the exhaust out as fast as possible (if we could run our downpipes right out through the wheel well, we should (if that was realistic, which it's not)).

Anyway, as the diameter gets bigger, the air can actually cool a little too much which slows down the air flow. Hot air exits through the pipes faster. The hotter the air the faster it moves. This is one of the main reasons DP's are wrapped or ceramic coated - to keep the internal air as hot as possible.

There was a ton of R&D done on the Subaru turbo exhausts and it was found that on a stock turbo setup, anything more than 3" resulted in a slight loss of power. Obviously with huge GT35R/65R setups pushing 500AWHP or more, bigger diameter was better, simply because of the amount of flow required.

Just something to think about - especially if you're getting a local exhaust shop to design your setup. And in the end, this is no Subaru, but the same rules applied to the Evo's, SRT-4's etc.

I agree. According to Steven (from EAS) going to anything larger than 3'' will result power loss. Bigger is not always better.

bimmerboy · 04-11-2010, 12:05 AM

Quote:

Originally Posted by bmore135

here is my vid... vk catless downpipes, Y to a 3" pipe, 1 high flow straight through resonator, and just tips. no muffler no cats...

Damn that sounds awesome!

frimmelnojerz · 04-11-2010, 12:59 AM

I've got all catless UR downpipes with CP-e midpipes and a berk street exhaust but no video..i'll take one sooner or later.

onefastman · 04-12-2010, 07:50 PM

Man this makes me want to take off the exhaust for the track day and just run dp's... I think I will have to do it

onefastman · 04-13-2010, 12:52 PM

Any idea if this will yeald any gains or losses?

Joe_435i · 02-13-2015, 02:14 AM

Quote:

Originally Posted by Chenry135

I have a custom exhaust on mine that is just a 3 1/2 inch pipe all the way back. No resonators or mufflers. It's pretty loud, but nothing extreme. I don't have DP's though so i guess that's why...

Did you keep the stock cats on or upgrade?

NORAGRETS · 02-14-2015, 02:49 PM

Quote:

Originally Posted by 135forthewin

I was just wondering if anyone out there has done a complete straight-through exhaust system.
What I mean by this is catless downpipes, catless midpipes, and a berk/afe/aa axleback.
If any has, I wanted to know how it sounds. I'm sure it SCREAMS!

So, is anyone planning on doing this/doing this already?

i have it...catless ar dp, catless berk mids, muffler delete berk race axle back

Boosted_N54 · 02-14-2015, 03:12 PM

so do we need back pressure or do we don't ? i thought the faster air flows out through the exhaust the faster the turbine spins

edisapimp · 02-14-2015, 03:16 PM

heated air makes the turbine spin, not just air.

Boosted_N54 · 02-14-2015, 04:12 PM

Quote:

Originally Posted by edisapimp

heated air makes the turbine spin, not just air.

yea I know . but which is best?

edisapimp · 02-14-2015, 04:26 PM

Quote:

Originally Posted by Brahmzy

Keep in mind the bigger the diameter, is not necessarily the better, depending on power output.
Yes it's true we want absolutely zero backpressure, however, you can still go "too big" on your piping, especially using stock trubos.

The point in a turbo-charged car is to get the exhaust out as fast as possible (if we could run our downpipes right out through the wheel well, we should (if that was realistic, which it's not)).

Anyway, as the diameter gets bigger, the air can actually cool a little too much which slows down the air flow. Hot air exits through the pipes faster. The hotter the air the faster it moves. This is one of the main reasons DP's are wrapped or ceramic coated - to keep the internal air as hot as possible.

There was a ton of R&D done on the Subaru turbo exhausts and it was found that on a stock turbo setup, anything more than 3" resulted in a slight loss of power. Obviously with huge GT35R/65R setups pushing 500AWHP or more, bigger diameter was better, simply because of the amount of flow required.

Just something to think about - especially if you're getting a local exhaust shop to design your setup. And in the end, this is no Subaru, but the same rules applied to the Evo's, SRT-4's etc.

this.

amsnow440 · 02-14-2015, 05:17 PM

Quote:

Originally Posted by Socrates.Tii

yea I know . but which is best?

They are both important. The work extracted from a turbine is a function of the change in velocity, change in enthalpy (which is a function of volume and pressure), and change in potential energy (negligible in this case) of the mass flowing through it.

Boosted_N54 · 02-14-2015, 06:50 PM

Quote:

Originally Posted by amsnow440

Quote:

Originally Posted by Socrates.Tii

yea I know . but which is best?

They are both important. The work extracted from a turbine is a function of the change in velocity, change in enthalpy (which is a function of volume and pressure), and change in potential energy (negligible in this case) of the mass flowing through it.

man I lost you. you sound to smart for me . I guess a dyno with full cat less and then catted would show the difference

NORAGRETS · 02-15-2015, 01:14 AM

you dont need back pressure...the cars are smart, the turbo does its work like it should. i feel no lag or anything, there are no drawbacks to no cats...

NORAGRETS · 02-15-2015, 01:15 AM

dyno w catless and w cats its pretty simple....

take the number you got with catless, mine was 320 whp subtract about 20-30 whp if you have cats....

there is a HUGE difference in power and torque without a catless dp

ive swapped it twice, youll DEF notice

02-12-2010, 02:15 PM	#23
Chenry135 First Lieutenant 3 Rep 301 Posts Drives: former 2008 135i/ 2006 STI Join Date: Jul 2009 Location: Atlanta, Ga iTrader: (0)	I have a custom exhaust on mine that is just a 3 1/2 inch pipe all the way back. No resonators or mufflers. It's pretty loud, but nothing extreme. I don't have DP's though so i guess that's why...
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02-13-2010, 11:11 AM	#24
ar design 295 Rep 4,408 Posts Drives: 04 M3 Join Date: Jan 2008 Location: Denver, CO iTrader: (9)	I had straight pipes on the 3. LOUD. __________________ -Critter
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02-23-2010, 11:12 PM	#26
6spdMSport Private 5 Rep 94 Posts Drives: Jet Black 135i Sport/USB/iPod Join Date: Aug 2009 Location: 727 iTrader: (-2)	Iam now running straight pipes, i have VK catless downpipes with a custom cat-back by miami mufflers. no mufflers, 2 2.5's into a single 3. its loud but i like it its worth it. __________________ 09 Jet Black 135i /// M-Sport BMS DCI /// JB3 2.0 /// AA Chargepipe & BOV /// AA FMIC /// VK Downpipes /// H&R Super-Sports /// SpunTek Custom Piping/// Miami Muffler Custom Cat-Back(Straight Pipe)/// BMS CDV/// Carbon Fiber Grills/// DEFI Boost Gauge
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04-08-2010, 08:13 PM	#27
evifytrihteno Enlisted Member 0 Rep 30 Posts Drives: 135i Join Date: Jul 2009 Location: Texas iTrader: (0)	I have 3" Catless Downpipes on my 1. I want full straight pipes for the rest of my exhaust (currently stock cat-back). Is there a pre-fabbed exhaust on the market that is 3" all the way to the back without a muffler? Thanks __________________ Year one of the 1 Black Sapphire 135i. Mods: JB3 1.4 (Map 7), BMS DCI, AR 3" downpipes
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04-08-2010, 10:27 PM	#28
onefastman Major General 159 Rep 5,689 Posts Drives: 2009 135i 2011 e92m dct Join Date: Sep 2009 Location: Earth iTrader: (15)	I am assuming that they are Ar or something to that effect. If that is the case then they are not actually 3", they start at 3 and taper to 2.5" to fit the exhausts made. Depending on your budgit (assuming you have some $ to spend) I would go with any catless mid pipe and a eissimann muffler (or meisterschaft). It will perform (not that the secondary cats do much) and sounds better than any system on the market. __________________ Legal Disclaimer: Anything I or anyone else says about my vehicle on this website(1addicts.com or any affiliated or nonaffiliated sites), pertaining to modifications, is only to gain acceptance from my/our peers, and does not actually represent anything actually existing on my car, and thus, cannot be held against me in any issues, i.e. warranty claims, that may arise.
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04-09-2010, 04:21 PM	#29
bmore135 Private First Class 13 Rep 190 Posts Drives: BSM 135i Join Date: Aug 2008 Location: Baltimore, MD iTrader: (0)	here is my vid... vk catless downpipes, Y to a 3" pipe, 1 high flow straight through resonator, and just tips. no muffler no cats...
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04-11-2010, 12:59 AM	#32
frimmelnojerz Captain 23 Rep 692 Posts Drives: Montego blue 135i Join Date: Jun 2008 Location: Bayonne, NJ iTrader: (0)	I've got all catless UR downpipes with CP-e midpipes and a berk street exhaust but no video..i'll take one sooner or later. __________________ 08' 135 in much need of some TLC. But after that... Watch out. AA/Berk/ER/UR/CP-e/Snow/ESS
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04-12-2010, 07:50 PM	#33
onefastman Major General 159 Rep 5,689 Posts Drives: 2009 135i 2011 e92m dct Join Date: Sep 2009 Location: Earth iTrader: (15)	Man this makes me want to take off the exhaust for the track day and just run dp's... I think I will have to do it __________________ Legal Disclaimer: Anything I or anyone else says about my vehicle on this website(1addicts.com or any affiliated or nonaffiliated sites), pertaining to modifications, is only to gain acceptance from my/our peers, and does not actually represent anything actually existing on my car, and thus, cannot be held against me in any issues, i.e. warranty claims, that may arise.
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04-13-2010, 12:52 PM	#34
onefastman Major General 159 Rep 5,689 Posts Drives: 2009 135i 2011 e92m dct Join Date: Sep 2009 Location: Earth iTrader: (15)	Any idea if this will yeald any gains or losses? __________________ Legal Disclaimer: Anything I or anyone else says about my vehicle on this website(1addicts.com or any affiliated or nonaffiliated sites), pertaining to modifications, is only to gain acceptance from my/our peers, and does not actually represent anything actually existing on my car, and thus, cannot be held against me in any issues, i.e. warranty claims, that may arise.
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02-14-2015, 03:12 PM	#37
Boosted_N54 Major 180 Rep 1,310 Posts Drives: 135i N54 Join Date: Apr 2008 Location: New York iTrader: (0)	so do we need back pressure or do we don't ? i thought the faster air flows out through the exhaust the faster the turbine spins __________________ MHD Custom Flash (E85) [Jake@MOTIV] / Vargas Stage 2 Turbos / Fuel it LPFP Stage 3+/ Moitiv Port Injection/ MMP Turbo Inlets/ 3.5 Tmap Sensor / ER FMIC /ER Chargepipe HKS-BOV / AA Downpipes / Agency Power Race mid pipes / Berk Technology race exhaust / BMW SSK / BC Forged Whees Toyo R888 tires / KW Club sport coilovers+KW Camber Plates / Spec stg2+Spec SMSFW/ APR Wing GTC200
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02-14-2015, 03:16 PM	#38
edisapimp Civil Rights Activist 115 Rep 949 Posts Drives: E46 Sedan, E88 Vert Join Date: Apr 2013 Location: Long Island iTrader: (0)	heated air makes the turbine spin, not just air. __________________ E88 Crimson Red Vert MSport 6MT - Listing your mods in your signature is lame. BMS DCI/MHD E30 Flash!!/AA Sport FMIC/VRSF CP w Tial BOV/VRSF 3" DPs/550i clutch w SPEC SMFW/Apex EC-7s/Whiteline RSFB/E92 M3 FCAs/Bilstein B12 Pro Kit/VRSF inlets
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02-15-2015, 01:14 AM	#43
NORAGRETS Colonel 441 Rep 2,037 Posts Drives: 2017 F80 M3 ZCP BSM 2012 E82 1 Join Date: May 2012 Location: Boston, MA iTrader: (0) Garage List 2017 BMW M3 ZCP LCI [0.00]	you dont need back pressure...the cars are smart, the turbo does its work like it should. i feel no lag or anything, there are no drawbacks to no cats... __________________ 2017 F80 ZCP BSM - Klein Innovation. ActiveAutowerkes. AR Design. BootMod3 Paul Johnson. EvRw. Project Gamma. RW Carbon. UCP. UUC. Hawk. Dinan. NGK. Macht Schnell. TMS. VR. aFe. RIP - E82 135i - 7/7/2021
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02-15-2015, 01:15 AM	#44
NORAGRETS Colonel 441 Rep 2,037 Posts Drives: 2017 F80 M3 ZCP BSM 2012 E82 1 Join Date: May 2012 Location: Boston, MA iTrader: (0) Garage List 2017 BMW M3 ZCP LCI [0.00]	dyno w catless and w cats its pretty simple.... take the number you got with catless, mine was 320 whp subtract about 20-30 whp if you have cats.... there is a HUGE difference in power and torque without a catless dp ive swapped it twice, youll DEF notice __________________ 2017 F80 ZCP BSM - Klein Innovation. ActiveAutowerkes. AR Design. BootMod3 Paul Johnson. EvRw. Project Gamma. RW Carbon. UCP. UUC. Hawk. Dinan. NGK. Macht Schnell. TMS. VR. aFe. RIP - E82 135i - 7/7/2021
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