Close

Page 2 of 2 FirstFirst 12
Results 26 to 44 of 44

Thread: straight pipes

  1. #26
    Join Date
    Oct 2010
    Location
    Baltimore, MD
    Posts
    747
    Rep Points
    698.9
    Mentioned
    3 Post(s)
    Rep Power
    7


    Reputation: Yes | No
    I remember when I had my N54, a lot of people said just keep stock exhaust, and drop some c@tless or sport catted DPs and that should be comparable to going straight pipes (not as good but just about). I went straight catless, not really by choice, but just happened to end up that way, and I loved it, but it was a PAIN to pass emissions and get everything working...just saying...I regretted everyday lol
    BimmerBoost's Resident n00b...Click here to enlarge

    Titanium Silver 2003 335 Ci || Premium Package || Sport Package || SOLD
    Sapphire Metallic Black 2008 535i || Custom Mandrel Bend Borla Exhaust || BMS Spacers || CMS Pro Meth Kit || JB4 || BMS DCI || SOLD
    Alpine White 2012 C63 Coupe || AMG Development Package || Multimedia Package || Lighting Package || LEASE ENDED
    Alpine White 2015 M3 || Driver Assistance Plus || Executive Package || Lighting Package || M Double-clutch and Adaptive M Suspension ||

    Click here to enlarge

  2. #27
    Join Date
    Feb 2012
    Location
    south florida
    Posts
    1,989
    Rep Points
    2,386.1
    Mentioned
    96 Post(s)
    Rep Power
    24


    Reputation: Yes | No
    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    No vendor makes a full 3" DP for the N54. AR, MS, VRSF, CP-e all make a 3" top that tapers down to 2.5" for the OEM midpipe connection. Akrapovic's DP is 2.75" and tapers to 2.5" (they saw no performance gains with that additional .25", but their R&D goes out the window when you start pushing over 500 WHP.



    If you're running the OEM Turbos, this is completely worthless IMO. Like other people have stated, by going 3" all the way back you'll lose "good" back pressure that creates TQ. The only purpose to going full 3" would be on a single turbo upgrade or the RB/Vargas TT upgrades that start pushing over 500 WHP. Unless you're building a purpose built race car (we're talking stripped interior, roll cage, not street legal), this is a unnecessary mod. If you're really that desperate to gain some extra power, invest in some Upgraded Turbos, Meth, Race Gas OR E85.
    i wonder how much power would be made by deleting the mid cats and putting in an x pipe and making it a true dual exhaust straight piped from there back?

  3. #28
    Join Date
    Jun 2012
    Location
    NJ
    Posts
    4,199
    Rep Points
    1,800.3
    Mentioned
    102 Post(s)
    Rep Power
    19


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Ak335i Click here to enlarge
    i wonder how much power would be made by deleting the mid cats and putting in an x pipe and making it a true dual exhaust straight piped from there back?
    With a quality built, properly designed X-pipe (2.5-3" width), you'd probably gain 5-10 WHP/10-15 WTQ (will gain more tq's with a non-restrictive, backpressure X). The biggest problem with this is will it clear all the underbody obstacles (much more difficult running a true dual pipe setup as opposed to a single, 3" exhaust).

    But like I said, if you're going super high HP (think HPF Turbo M3s, single turbo N54s), it's more beneficial to go with a simple 3" single exhaust
    COBB AP ProTune by Bren of ///Bren Tuning
    Akrapovic DP | Helix FMIC | Alpina TCM Flash | Walbro 450LPH Fuel Pump


    "The moment money becomes your motivation, you are immediately not as good as someone who is motivated by passion and internal will." -A. Senna

  4. #29
    Join Date
    May 2012
    Location
    Toronto, Canada
    Posts
    187
    Rep Points
    395.9
    Mentioned
    7 Post(s)
    Rep Power
    4


    Reputation: Yes | No
    Resonators weigh about 3 pounds and remove your current piping which probably brings it down to 2.5 pounds... take a $#@! before driving or something.

    What kind of goals do you have for this car where every little pound makes a difference? There are so many other areas to improve this car before worrying about a couple pounds. If the weight of a resonator is what makes the difference in winning or losing a race just ask to do another run and this time remove your pants and toss them out the sunroof.

    Another thing to consider is this: all of these THEORETICAL gains people speak of by doing mod x, y or z, where are those gaines being made? Is it worth having your car sound like a broken piece of $#@! to gain 4whp from 4200-4400 rpm?

    There's a lot of other ways to save weight on the car and a lot of them are way more efficient.
    jb4+fbo+meth

  5. #30
    Join Date
    Sep 2012
    Location
    Brisbane, Australia
    Posts
    3,270
    Rep Points
    1,418.4
    Mentioned
    53 Post(s)
    Rep Power
    15


    Reputation: Yes | No
    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    No vendor makes a full 3" DP for the N54. AR, MS, VRSF, CP-e all make a 3" top that tapers down to 2.5" for the OEM midpipe connection. Akrapovic's DP is 2.75" and tapers to 2.5" (they saw no performance gains with that additional .25", but their R&D goes out the window when you start pushing over 500 WHP.
    how come all their product pages state 'full 3" '... that's exact quotes from the VSRF AR, BMS pages. that's blatant false advertising!,

    http://www.burgertuning.com/BMS_135_335_downpipes.html

    says 'Full 3"' on that page :/

    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    If you're running the OEM Turbos, this is completely worthless IMO. Like other people have stated, by going 3" all the way back you'll lose "good" back pressure that creates TQ. The only purpose to going full 3" would be on a single turbo upgrade or the RB/Vargas TT upgrades that start pushing over 500 WHP. Unless you're building a purpose built race car (we're talking stripped interior, roll cage, not street legal), this is a unnecessary mod. If you're really that desperate to gain some extra power, invest in some Upgraded Turbos, Meth, Race Gas OR E85.
    exhaust scavenging need not be a consideration, and backpressure doesn't increase tq on a turbo vehicle, it hinders it by slowing down spool time (gases pushing back against the turbine blades)

    scavenging/backpressure is only a *big* consideration for N/A vehicles, as soon as you add a system that pushes the air in and out with positive pressure (a la boost), it's all done automatically and forcefully...

    add to that, the turbo acts as a harmonic filter, which actually removes the 'resonance' in the pulses, so you don't really get it as strongly.

    torque in a turbocharged motor should be created almost entirely by boost, the sooner you get boost, the sooner you get torque.

  6. #31
    Join Date
    Sep 2012
    Location
    Brisbane, Australia
    Posts
    3,270
    Rep Points
    1,418.4
    Mentioned
    53 Post(s)
    Rep Power
    15


    Reputation: Yes | No
    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    With a quality built, properly designed X-pipe (2.5-3" width), you'd probably gain 5-10 WHP/10-15 WTQ (will gain more tq's with a non-restrictive, backpressure X). The biggest problem with this is will it clear all the underbody obstacles (much more difficult running a true dual pipe setup as opposed to a single, 3" exhaust).

    But like I said, if you're going super high HP (think HPF Turbo M3s, single turbo N54s), it's more beneficial to go with a simple 3" single exhaust
    for further working out as to what you should get

    a 3" by 10" pipe has an internal volume of 70ci
    a 2.5" by 10" pipe has an internal volume of 49ci (so a dual 2.5" has an internal volume of 98ci)

    the closest single exhaust to a dual 2.5" would be a single 3.5" (96ci at 10" long)

    if you could fit a single 3.5 from the axle back ,with twin 2.5's (what's stock? twin 2" into 2.5" for n52 powered cars, so AT LEAST that big), that'd be perfect

  7. #32
    Join Date
    Aug 2010
    Location
    over there
    Posts
    288
    Rep Points
    481.1
    Mentioned
    14 Post(s)
    Rep Power
    5



    Reputation: Yes | No
    Again i dont really care at all how my car sounds so thats a non issue for me.

    Also for the people who are saying dual 3 inch exhaust wont add power on stock turbos i dont plan on staying on stock turbos for much longer im just waiting for vargas to come out with the gtx turbo kit.

    One last point to talk about clearance dual 3 inch would fit no problem. I dont see a need in going single 3 inch as that would be a downgrade but a single 3.5 inch or single 4 inch would do well and there is room for that as well i just prefer the dual 3 inch option
    Turbo lag is the on ramp to the highway which is power.

  8. #33
    Join Date
    May 2012
    Location
    Jacksonville, FL
    Posts
    2,937
    Rep Points
    2,858.9
    Mentioned
    78 Post(s)
    Rep Power
    29


    Reputation: Yes | No
    Click here to enlarge Originally Posted by WDBi Click here to enlarge
    Again i dont really care at all how my car sounds so thats a non issue for me.

    Also for the people who are saying dual 3 inch exhaust wont add power on stock turbos i dont plan on staying on stock turbos for much longer im just waiting for vargas to come out with the gtx turbo kit.

    One last point to talk about clearance dual 3 inch would fit no problem. I dont see a need in going single 3 inch as that would be a downgrade but a single 3.5 inch or single 4 inch would do well and there is room for that as well i just prefer the dual 3 inch option
    Big weight savings when going single 3.5" or 4", should be close to 40lbs.
    2011 E90 M3 \ Melbourne Rot Metallic

    Click here to enlarge

  9. #34
    Join Date
    Sep 2012
    Location
    Brisbane, Australia
    Posts
    3,270
    Rep Points
    1,418.4
    Mentioned
    53 Post(s)
    Rep Power
    15


    Reputation: Yes | No
    Dual 3's would probably get you to 1000whp , 800+ at minimum..


    you also have to remember that the exhaust gases cool and slow down by the time it hits the muffler so it's not always entirely neccessary to keep the same diameter.. In fact, by the time you hit the axel back, too large a piping can slow down flow which causes restrictions further up, you have to make sure it's appropriately sized the whole way.

    how are you going to deal with the part of the exhaust which moves around the diff? A single 3" is a tight squeeze, i can almost guarantee dual 3's will NOT fit around the diff/suspension components, unless you can show me some pics?.. That's 6" of piping, day .125" clearance either side.
    http://farm4.static.flickr.com/3536/4014517275_ec2f4b876e.jpg
    Last edited by Flinchy; 11-02-2012 at 09:13 AM.

  10. #35
    Join Date
    Aug 2010
    Location
    over there
    Posts
    288
    Rep Points
    481.1
    Mentioned
    14 Post(s)
    Rep Power
    5



    Reputation: Yes | No
    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    Dual 3's would probably get you to 1000whp , 800+ at minimum..


    you also have to remember that the exhaust gases cool and slow down by the time it hits the muffler so it's not always entirely neccessary to keep the same diameter.. In fact, by the time you hit the axel back, too large a piping can slow down flow which causes restrictions further up, you have to make sure it's appropriately sized the whole way.

    how are you going to deal with the part of the exhaust which moves around the diff? A single 3" is a tight squeeze, i can almost guarantee dual 3's will NOT fit around the diff/suspension components, unless you can show me some pics?.. That's 6" of piping, day .125" clearance either side.
    http://farm4.static.flickr.com/3536/4014517275_ec2f4b876e.jpg
    the shop who will be doing the work looked at it and believes that a dual 3 inch would be the best bet. A single 3.5 inch would be a downgrade and actually so would a single 4 inch. Im not talking downgrade when it comes to stock exhaust im talking about the general flow considering the downpipes start at dual 3 inch a single 4 inch isnt as big as dual 3 inch pipes. Also about weight dual 3 inch titanium exhaust shouldnt even weigh 25 pounds a supra 4 inch exhaust with muffler weights 12lbs lol.
    Turbo lag is the on ramp to the highway which is power.

  11. #36
    Join Date
    Jun 2012
    Location
    NJ
    Posts
    4,199
    Rep Points
    1,800.3
    Mentioned
    102 Post(s)
    Rep Power
    19


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    exhaust scavenging need not be a consideration, and backpressure doesn't increase tq on a turbo vehicle, it hinders it by slowing down spool time (gases pushing back against the turbine blades)

    scavenging/backpressure is only a *big* consideration for N/A vehicles, as soon as you add a system that pushes the air in and out with positive pressure (a la boost), it's all done automatically and forcefully...
    Just wanted to correct you that your original statement was more correct that backpressure is less important on turbo'd cars. On both N/A and supercharged applications, backpressure is very important to tq. Perfect example is the E9x M3 and how the X placement actually chances how each X-pipe performs (ex: Gintani X vs. eBay X)

    Click here to enlarge Originally Posted by WDBi Click here to enlarge
    One last point to talk about clearance dual 3 inch would fit no problem. I dont see a need in going single 3 inch as that would be a downgrade but a single 3.5 inch or single 4 inch would do well and there is room for that as well i just prefer the dual 3 inch option
    Save yourself the frustration of making a custom dual 3" CBE & buy the HPF 3.5" exhaust. You'll save ~40lbs, it's rated up to 800 RWHP
    and really is a quality piece that makes perfect sense for your goals: http://www.horsepowerfreaks.com/part...ems/335i/17308
    COBB AP ProTune by Bren of ///Bren Tuning
    Akrapovic DP | Helix FMIC | Alpina TCM Flash | Walbro 450LPH Fuel Pump


    "The moment money becomes your motivation, you are immediately not as good as someone who is motivated by passion and internal will." -A. Senna

  12. #37
    Join Date
    Sep 2012
    Location
    Brisbane, Australia
    Posts
    3,270
    Rep Points
    1,418.4
    Mentioned
    53 Post(s)
    Rep Power
    15


    Reputation: Yes | No
    Click here to enlarge Originally Posted by WDBi Click here to enlarge
    the shop who will be doing the work looked at it and believes that a dual 3 inch would be the best bet. A single 3.5 inch would be a downgrade and actually so would a single 4 inch. Im not talking downgrade when it comes to stock exhaust im talking about the general flow considering the downpipes start at dual 3 inch a single 4 inch isnt as big as dual 3 inch pipes. Also about weight dual 3 inch titanium exhaust shouldnt even weigh 25 pounds a supra 4 inch exhaust with muffler weights 12lbs lol.
    well a single 4" would be 125.7ci in a 10" cylinder, dual 3's would be 140ci, you're still WAY above a dual 2.5 or something

    a dual 3" in titanium will also set you back a couple of thousand dollars, easily.

    so yeah, downgrade, but you realize dual 3's are run in twin turbo V8's pushing well over 1000hp yeah?.. so unless you're planning on a 1000hp setup, it really is entirely unneccesary... even with RB's, a 4" would be overkill.

    and what i mentioned above, with exhaust flow slowing down from turbo to muffler.. dual 3's to a single 4" would be totally acceptable

    i still don't think dual 3"s will clear the diff...

    not to mention apparently all downpipes taper to a 2.5" outlet? which i still kinda find hard to believe considering the advertising..

    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    Just wanted to correct you that your original statement was more correct that backpressure is less important on turbo'd cars. On both N/A and supercharged applications, backpressure is very important to tq. Perfect example is the E9x M3 and how the X placement actually chances how each X-pipe performs (ex: Gintani X vs. eBay X)



    Save yourself the frustration of making a custom dual 3" CBE & buy the HPF 3.5" exhaust. You'll save ~40lbs, it's rated up to 800 RWHP
    and really is a quality piece that makes perfect sense for your goals: http://www.horsepowerfreaks.com/part...ems/335i/17308
    it's also not as important on a supercharged car, as the supercharger forces air out, with slight valve overlap even.

    backpressure is a moot point when the air is forced out by the supercharger.

    on a N/A M3, of course it's very important.. it's N/A lol

  13. #38
    Join Date
    Feb 2012
    Location
    south florida
    Posts
    1,989
    Rep Points
    2,386.1
    Mentioned
    96 Post(s)
    Rep Power
    24


    Reputation: Yes | No
    For the OP. real world gains. I deleted 2nd cats and put in a high flow muffler with built in X-pipe and deleted that h pipe resonator thing. I now have a true dual 2.5 inch exhaust straight piped
    Taking the average of all my runs Wednesday and all my runs tonight, I averaged .5mph more and .05 sec faster tonight with a DA of around 900ft vs 200ft wednesday. So the gains are real. What that means is I went faster (speed) and quicker ET when I should have gone slower. You are doing big things, don't let the people get ya down lol.

  14. #39
    Join Date
    Aug 2010
    Location
    over there
    Posts
    288
    Rep Points
    481.1
    Mentioned
    14 Post(s)
    Rep Power
    5



    Reputation: Yes | No
    Click here to enlarge Originally Posted by Ak335i Click here to enlarge
    For the OP. real world gains. I deleted 2nd cats and put in a high flow muffler with built in X-pipe and deleted that h pipe resonator thing. I now have a true dual 2.5 inch exhaust straight piped
    Taking the average of all my runs Wednesday and all my runs tonight, I averaged .5mph more and .05 sec faster tonight with a DA of around 900ft vs 200ft wednesday. So the gains are real. What that means is I went faster (speed) and quicker ET when I should have gone slower. You are doing big things, don't let the people get ya down lol.
    im not i know what im doing when it comes to this stuff. and yes dual 3 inch may be overkill but anything else is technically a restriction because the downpipes start as 3 inch so you cant talk about singles being equal to 2.5 because you want them to be equal or bigger to dual 3 inch. also i know its going to cost money. i know its going to be overkill. but i will make more power no matter how small of gains than others. Oh and to the people doubting dual 3 inch will fit the shop was playing around with my car the other day and said they could get 3.5 duals to work.

    Why do i trust this shop you say? Because to look at my car they pulled a 3000hp camaro that runs 170mph in the 1/8th mile off the lift to look at my car...
    Turbo lag is the on ramp to the highway which is power.

  15. #40
    Join Date
    Sep 2012
    Location
    Brisbane, Australia
    Posts
    3,270
    Rep Points
    1,418.4
    Mentioned
    53 Post(s)
    Rep Power
    15


    Reputation: Yes | No
    Click here to enlarge Originally Posted by WDBi Click here to enlarge
    im not i know what im doing when it comes to this stuff. and yes dual 3 inch may be overkill but anything else is technically a restriction because the downpipes start as 3 inch so you cant talk about singles being equal to 2.5 because you want them to be equal or bigger to dual 3 inch. also i know its going to cost money. i know its going to be overkill. but i will make more power no matter how small of gains than others. Oh and to the people doubting dual 3 inch will fit the shop was playing around with my car the other day and said they could get 3.5 duals to work. Why do i trust this shop you say? Because to look at my car they pulled a 3000hp camaro that runs 170mph in the 1/8th mile off the lift to look at my car...
    Is it one pipe either side of the diff or what? One pipe per side is a squeeze!

  16. #41
    Join Date
    Sep 2012
    Location
    Brisbane, Australia
    Posts
    3,270
    Rep Points
    1,418.4
    Mentioned
    53 Post(s)
    Rep Power
    15


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    Is it one pipe either side of the diff or what? One pipe per side is a squeeze!

    Ah never mind, quick images search showed yeah pipe either side, sorr i'm used to the 135i setup that has the battery on the left so no pipe can go there

    without MAJOR mods, the best a 135i could do is a single sided exhaust wiyh a 3.5" would be the biggest for them lol



    an like i said, dual 3" is good all the way to the diff yes, but even if you stepped down to a dual 2.5, the gas flow is slow enough by then that at worst you'd see a couple hp loss, and potentially see a gain due to larger pipes slowing down flow TOO much

  17. #42
    Join Date
    Feb 2010
    Location
    Miami Beach
    Posts
    1,092
    Rep Points
    513.1
    Mentioned
    10 Post(s)
    Rep Power
    6


    Reputation: Yes | No
    You already know this but 3inch is overkill and with your current setup I'm willing to bet your actually make you car slower, but try it out. They're acouple videos on YouTube of a 3inch exhaust. I know someone with 135i with bigger turbos that he told me he saw more power out of a single 4 inch then a single 4.5. Or was it 3.5 to 4? W/e the moral of the story is that bigger isn't always better.

    Your right that a single 3.5 like hpf flows a little bit less then a dual 2.5, but neither is going to hold you back until you get to ~800whp. Theirs a equation you can do to figure out how big of an exhaust you need. Your honestly better off staying the way you are and spending your money on a tune or meth kit if you haven't already(biggest bang for the buck). any other mod would be better then continuing to spend money on a exhaust your never going to max out.

    Once my motor is back together I was planning on doing a separated 2.5 with 2 small resonators to control the rasp. No mufflers or xpipe for me !
    Click here to enlarge

  18. #43
    Join Date
    Sep 2012
    Location
    Brisbane, Australia
    Posts
    3,270
    Rep Points
    1,418.4
    Mentioned
    53 Post(s)
    Rep Power
    15


    Reputation: Yes | No
    Click here to enlarge Originally Posted by lamia2super Click here to enlarge
    You already know this but 3inch is overkill and with your current setup I'm willing to bet your actually make you car slower, but try it out. They're acouple videos on YouTube of a 3inch exhaust. I know someone with 135i with bigger turbos that he told me he saw more power out of a single 4 inch then a single 4.5. Or was it 3.5 to 4? W/e the moral of the story is that bigger isn't always better.

    Your right that a single 3.5 like hpf flows a little bit less then a dual 2.5, but neither is going to hold you back until you get to ~800whp. Theirs a equation you can do to figure out how big of an exhaust you need. Your honestly better off staying the way you are and spending your money on a tune or meth kit if you haven't already(biggest bang for the buck). any other mod would be better then continuing to spend money on a exhaust your never going to max out.

    Once my motor is back together I was planning on doing a separated 2.5 with 2 small resonators to control the rasp. No mufflers or xpipe for me !
    no xpipe could lead to strange sound/unequal exhaust flow, no?

  19. #44
    Join Date
    Feb 2010
    Location
    Miami Beach
    Posts
    1,092
    Rep Points
    513.1
    Mentioned
    10 Post(s)
    Rep Power
    6


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    no xpipe could lead to strange sound/unequal exhaust flow, no?
    not really and if you noticed AE exhaust doesn't use a xpipe, so im not the first person doing this. if memory serves correct shiv had removed his xpipe yrs ago. the xpipe is supposed to take advantage of a scavenging affect that takes place and it is said to cut back on rasp and drone. i think its all a marketing trick to get more money out of you, but i could be wrong. ive always wanted to try separating my exhaust and find out the difference for myself. i currently don't have a exhaust so once i get my car back ill have to drive it with just the dpsClick here to enlarge(should be interesting) until i can drop it off at a exhaust shop
    Click here to enlarge

Page 2 of 2 FirstFirst 12

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •