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Steelpack Mufflers & X-Pipe?

Discussion in 'The Hokey Ass Message Board' started by AAFD, Jul 25, 2010.

  1. AAFD
    Joined: Apr 13, 2010
    Posts: 585

    AAFD
    Member
    from US of A

    I'm about to re-do the exhaust on my car. It's got a stock SBC with Headers, 2.5" exhaust and Flowmasters, with the pipes coming out right before the rear tires. I hate the sound, and the pipes were done by the previous owner in a neanderthal way.

    I've got a new set of 17" Brockman Mellowtone Steel Pack Mufflers. I'm planning to reduce the pipe size to 2.25" after the collectors. Then run a 2.5" X-pipe just behind the transmission. The Brockman's will be mounted as far back as possible, but I don't have room to run the system out the back due to the fuel tank & suspension, so the pipes will either run 90-degrees out in front of the rear tires, or I'll run them 180-degrees around facing the front, then another 180-degrees around so the pipes will run along side the running boards and dump before the rear tires. (See my quick drawing in photo, it shows both exhaust routes)

    I'm curious to know if the X-pipe is going to take that famous sound away from the mufflers? I know it will reduce alot of the "brap", which is great for highway driving since I drive this car 60 miles a day on the highway, but is the X-pipe going to kill the sound? Are the extra 180-degree bends in the pipes going to affect the sound in a bad way? I could go either way on this...I don't HAVE to run the X-pipe. I could run an H-Pipe, or no crossover at all. I'm trying to keep the rumble at around town speeds, but keep the ear blasting down at highway speeds. I average 2400-2800 RPM on the highway.

    Any input is appreciated.
     

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  2. Merlin
    Joined: Apr 9, 2005
    Posts: 2,546

    Merlin
    Member
    from Inman, SC

    I've heard both and have decided on a H pipe for my 54, IMO it doesn't loose the sound like an X does.
     
  3. AAFD
    Joined: Apr 13, 2010
    Posts: 585

    AAFD
    Member
    from US of A

    Pitts...sure that sounds great for what it is. But I'm not even making a 3rd of the power that car is making, and I'm not running Spintech mufflers (Which have a sound all their own)

    I just want to know what an X-pipe, or H-pipe is going to do to the sound of the mufflers. Since my pipes don't run straight out the back, the sound coming off each side is going to be very different than all 8 cylinders coming out the rear.

    As soon as the parts stores open I'm going to run down there and get some pipe & bends and put my mufflers on and run the 90-degree bends out to the sides. I have an X-pipe that I got at a swap meet, and I have an old H-pipe kit somewhere in the garage, so maybe one day I'll do the experiment myself. I wish I could run the pipes out the back, because I wouldn't worry about the crossover pipe or anything, but until I relocate the aftermarket fuel tank I'm stuck running them out to the side.
     
  4. AAFD
    Joined: Apr 13, 2010
    Posts: 585

    AAFD
    Member
    from US of A

    Just bought my pipes & bends. Going to install it all later today. Just running the mufflers about midway, no crossover, with some 45-degree bends, and some chrome pencil tips out the sides before the rear tires. It should be obnoxiously loud, but I can always change it when I have more time. I just want the Flowmasters in the scrap pile already.
     

  5. LSGUN
    Joined: May 26, 2007
    Posts: 1,338

    LSGUN
    Member
    from TX

    You'll have better flow with an X, but an H pipe will give your exhaust a deeper tone.
     
  6. KScooter
    Joined: Sep 22, 2009
    Posts: 105

    KScooter
    Member
    from California

    Run an X-pipe, but keep the full diameter of the tubing from the headers until *after* the X. That will keep the flow rate high and the sound deep. If you get the "X" from Dr. Gas, they have some that are one size in, and another size out, so you can use smaller pipes after the X and don't need a reducer pipe.

    Remember when thinking pipe diameter, the exhaust gases are cooling as they travel through the system. You can get away with smaller diameter pipes the further you go back through the system, especially if you use an X-pipe. The X-pipe design enables each side of the system to utilize both mufflers, reducing the size required to maintain flow and keep the sound. (As opposed to an "H" pipe, which just lets the pressure pulse expand back and forth inside the crossover, but does nothing to increase flow.) Because exhaust flow is actually a series of pressure waves and is not constant through the length of the pipe, when the pulse reaches the X, it expands and continues into both pipes and mufflers, so the pipe diameter can be reduced after the X with no loss in power.

    That also makes any restriction after the X less apparent to the engine, since it's using both tailpipes for all the engine's cylinders.

    Sorry for the long-winded post! Hope it helps.
     
  7. AAFD
    Joined: Apr 13, 2010
    Posts: 585

    AAFD
    Member
    from US of A

    Well, I put the new steel packs in about a foot ahead of where the flowmasters were, this puts them about 1.5' from the collectors. So there is 1.5' of 2.5" tubing, then it reduces into 2" into the mufflers, then remains 2" out to the sides.

    It sounds great on the road at all speeds, but at idle, it sounds like total shit. I mean it sounds downright TERRIBLE! I'm going to install my H-pipe in the next few days and see what that does.

    If I still don't like it, I'll run it over to my buddies muffler shop and we'll come up with a new complete 2" system, and maybe try to sneak some pipes out to the bumper if it's at all possible. I think the 2.5" is killing the sound before the mufflers, and there's not enough coming out at the tips to have that good idle sound. Over at my buddies muffler shop we can clamp the X-pipe in just to see how it sounds before welding anything. I'm tired of laying on my back.

    Oh well!
     
  8. fiftyv8
    Joined: Mar 11, 2007
    Posts: 5,298

    fiftyv8
    Member
    from CO & WA

    Great info thanks.
     

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