This message is marked as Important.

Subject: If you remove the resonator, on an E38 you will need an X or H pipe Author: HighLine740iL : member since February, 2005 : 2241 posts Posted on: 2009-10-08 10:42:28

You can even go with Straight Pipes when you remove the resonator.

Steve Dinan wrote a very good article on BMW exhaust. Please Read it first. Then the Exhaust Scavenging

The X pipe creates a condition known a exhaust scavenging. The stock resonator is an overweight X-Pipe. The difference between the stock resonator/x pipe is the baffeling to quite noise levels down for civilized driving.

The exhaust scavenging part...the two paths of gas from each side of the engine creates different exhaust "times" due to the firing order of the cylinders. So the exhaust gas is not constant flow of gas exting the manifold...it is a timed sequence of exhaust gas leaving the engine. The X pipe will create a collision of exhaust gas to mix together, create low turbulence, pull the gas away from the exhaust valves in the cylinder head and balance out the flow into the lower exhaust system into the cats & mufflers.


Exhaust Scavenging read about it here
Dinan Exhaust Theory
Another Dinan article on exhaust


Regards,
Mike

• Question regarding these new Magnaflows. I was not planning on removing anything (pic) - Ratt 2009-10-07 02:16:18 (1019 views)
  • Here are some pics of the project...sorry forgot to take some early in the (pic) - Ratt 2009-10-09 00:41:42 (998 views)
    • Very nice very sharp! Looks Great! (nt) - HighLine740iL 2009-10-09 20:08:43 (266 views)
    • NICE! I have the same setup. the only thing that i wished i did different is mou - rudye38 2009-10-09 10:24:46 (280 views)
      • Send some pics! Let me see what you got! (nt) - Ratt 2009-10-10 02:20:56 (192 views)
    • Looking good there! Have fun with them! (nt) - Edwin™ 2009-10-09 08:59:21 (183 views)
    • Nice! Those cutouts turned out beutifully with the door trim - sdmike 2009-10-09 00:44:49 (213 views)
      • Sorry - forgot to mention...WTB Mufflers in Poway on Pomerado. Guy is Marlon. - Ratt 2009-10-09 00:49:39 (258 views)
        • West side of Pomerado just north of Poway Road? - sdmike 2009-10-09 00:51:46 (172 views)
          • Yep - back right corner next to the Smog Station - Go get it done!! (nt) - Ratt 2009-10-09 00:59:22 (171 views)
            • Wanna drive yours first (nt) - sdmike 2009-10-09 01:35:46 (154 views)
              • Gotta say - it adds a certain somethin!! (nt) - Ratt 2009-10-09 13:20:44 (182 views)
  • I KNOW THEY ARE DONE! POST PICTURES, DAMMIT! (nt) - sdmike 2009-10-08 23:51:33 (210 views)
    • Workin on it now! (nt) - Ratt 2009-10-08 23:52:58 (166 views)
      • Hurry the hell up, I want to go to bed. LOL (nt) - sdmike 2009-10-09 00:39:48 (165 views)
  • I think you're going this way, but leave the center resonator and replace.. - sdmike 2009-10-08 12:58:58 (275 views)
  • If you remove the resonator, on an E38 you will need an X or H pipe (url) - HighLine740iL 2009-10-08 10:42:28 (10959 views)
    • I have 2 750's... one with straight thru pipes from the cats back - woody750 2009-10-08 12:46:36 (361 views)
      • Woody YGM! (nt) - HighLine740iL 2009-10-08 18:56:40 (162 views)
      • Woody, Cool! Thank you very much for the guidance! HELP What option to do?????? - HighLine740iL 2009-10-08 18:52:53 (208 views)
        • OPTION TWO... you get the best of both worlds done properly - woody750 2009-10-09 09:31:26 (217 views)
          • Thanks Woody!!! I appreciate the info. Oprion 2 it will be!! (nt) - HighLine740iL 2009-10-09 20:10:46 (177 views)
            • Oprion 2 it will be with the Remus Mufflers (url) - HighLine740iL 2009-10-09 21:28:30 (222 views)
      • Any droning at certain RPM's? (nt) - sdmike 2009-10-08 12:59:39 (181 views)
        • Exhaust noise is loud in back seat under heavy throttle - woody750 2009-10-09 10:27:05 (202 views)
  • Why are you swapping? Is your exhaust bad? Anyway, can't wait - Wiggi 2009-10-07 23:53:16 (162 views)
  • Look forward to seeing the finished product - BJames38 2009-10-07 22:37:14 (153 views)
    • I got these on ebay model 14816. But check with in your area for distributors of - Ratt 2009-10-08 20:14:26 (194 views)
  • I have not done this, but I did drive a car WITH the resonators intact... - Tim G in Central NJ 2009-10-07 15:56:59 (237 views)
    • Tim - your description of the sound is right on...If the resonator was removed - Ratt 2009-10-09 01:03:38 (184 views)
    • Thanks Tim - I have decided to leave the resonator intact. Your comments - Ratt 2009-10-07 17:12:26 (164 views)
      • Awesome! Can't wait to see 'em......! (nt) - Tim G in Central NJ 2009-10-07 17:51:17 (152 views)
  • I think there should be a posting of everyones exhaust recorded sounds - bmer_d 2009-10-07 15:45:51 (154 views)
    • +1000000 (nt) - HighLine740iL 2009-10-08 18:55:04 (151 views)
      • +1000000..One of the MOST ASKED questions on this board...Farhod`s muffler dele - Snitch740i 2009-10-08 20:23:30 (172 views)
    • Mine is completely stock so you would only hear a slight rumble (nt) - stevekc 2009-10-08 03:20:00 (175 views)
  • dont remove the resonator...i made that mistake and lost a noticable amount of - farhod 2009-10-07 03:23:19 (349 views)
    • Isn't that shit illegal anyway? - stevekc 2009-10-07 04:20:23 (183 views)
      • Only if you delete the cats, vehicle would throw a SES/CEL (shit fit) you'd fail - HighLine740iL 2009-10-08 19:00:36 (188 views)
        • Mine is old enough that they only do a visual for emissions testing - stevekc 2009-10-09 00:32:34 (169 views)
          • You're Lucky!!! (nt) - HighLine740iL 2009-10-09 20:11:45 (158 views)
          • My '95 gets the treadmill and rubber-glove treatment up the pipe. Maybe cuz its - Ratt 2009-10-09 01:12:32 (156 views)
            • yes, because of California. I'm a CA native and understand. Maryland just checks - HighLine740iL 2009-10-09 20:14:12 (141 views)
              • Never had any problems passing - do you think the new exhaust could pose a - Ratt 2009-10-10 03:25:21 (153 views)
      • My Aspen Silver 750 has NO resonator or mufflers... - woody750 2009-10-07 10:44:13 (273 views)
        • Any Pictures Woody? Thank you in advance (nt) - HighLine740iL 2009-10-08 18:56:02 (165 views)
      • im not sure...here in ca i havent had any problems with it..and i dont know what - farhod 2009-10-07 10:35:01 (153 views)