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  1. #11

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    Here's what an H-Pipe looks like. It's simply a small piece of pipe to connect the pipes that come out from both sides of the engine which helps balance out the exhaust flow on each side of the exhaust system. And yes, it is fairly common. They'll know what you mean when you tell them. And don't let them trick you and tell you it's gonna cost an ungodly amount extra. It's literally just a piece of pipe welded in between the existing pipes. Shouldn't cost too crazy.

    Last edited by c_m_chance; 04-30-2010 at 08:53 PM.
    MY LUG NUTS REQUIRE MORE TORQUE THAN YOUR RICER MAKES! :sign0011:

    2004 Silverado 2500 "Judas"
    Crew Cab and Short Bed
    6.0L Vortec
    Diablo Predator
    True Dual Exhaust: Hooker MaxFlow Mufflers and X-Pipe
    Drop-In K&N Air Filter
    Alpine Stereo System: iDA-x303 Deck, SPS-600 Front and Rear Speakers, KTP-445 Amplifier

    Future Upgrades Include:
    Cosmetic/Other: Spray-In Bed Liner, HID head lights, Leveling Kit
    Performance: Underdrive Pulleys

  2. #12

    Default

    out of curiosity, would i get a better hp gain if i set up my exhaust just like that one ? except after the cats of course.

  3. #13

    Default

    Wellll...I'll leave that one for you to decide, cus it's a close call in my opinion. If you are wanting more low end torque, then you don't want to over flow your exhaust. If you lose too much back-pressure, then you will lose torque.

    With the 4.8L Vortec that you have, it is rated at 300HP stock. Rule of thumb is, for every 1HP, you should have 2.2CFM of exhaust flow. So that means for 300HP, you should have about 660 CFM of exhaust flow. So, if you were to true dual your exhaust similar to this picture, you would be at about 500 to 600CFM per side (about 1000CFM total or more). (Something to note, 2.5" straight pipe flows about 570CFM.) So your limiting factor would be the muffler's you install and what they flow.

    Now, with that said, it would sound like a good idea to true dual your truck if you consider that the average muffler flows about 300 to 400CFM. This would put you somewhere between 600 and 800CFM. Perfect for a 300 horse engine. But something else that should be considered is just the shear size of your engine. It's only 4.8L. True dual might be a bit too much for the 4.8L and you would probably get better numbers and better response out of a dual in/dual out system and just stick with one muffler. The reason I say this is because when you have a smaller size engine, it becomes easy to over flow the exhaust. I think on average, the line where it becomes beneficial to actually true dual is when you start getting around 5.3L or more. The difference is simply because larger engines have more air/fuel mixture that is being combusted that they need to get out of that engine, where smaller engines don't have as much. Unless you have some major mods like forced induction or something, then I would stray away from a true dual on the 4.8.

    Definitely get someone else's opinion though who has the 4.8L and has done a true dual on it. My thinking processes is just from calculations and my own reasoning. But the realistic results that someone has are much more helpful than my thoughts lol.
    MY LUG NUTS REQUIRE MORE TORQUE THAN YOUR RICER MAKES! :sign0011:

    2004 Silverado 2500 "Judas"
    Crew Cab and Short Bed
    6.0L Vortec
    Diablo Predator
    True Dual Exhaust: Hooker MaxFlow Mufflers and X-Pipe
    Drop-In K&N Air Filter
    Alpine Stereo System: iDA-x303 Deck, SPS-600 Front and Rear Speakers, KTP-445 Amplifier

    Future Upgrades Include:
    Cosmetic/Other: Spray-In Bed Liner, HID head lights, Leveling Kit
    Performance: Underdrive Pulleys

  4. #14

    Default

    Wow, thanks for the responses, it appears you have a wealth of knowledge in those opinions of yours. but anyway, you mentioned a dual in dual out. Would that act as an H Pipe? or would i still have to incorporate an h pipe somewhere in there ? Also, how would that sound? i know it's hard to answer that kind of question, but i don't want it to be terribly loud. However, if that's the case, i'd sacrifice a bit of sound for more power.

  5. #15

    Default

    The dual in/dual out mufflers muffler's wont really act like an H-Pipe because the muffler is slowing the flow down a good bit. Plus, by the time the exhaust gets to your muffler, it's basically considered exited out of the truck. If you look at the point of view of the engine, all it notices is the exhaust up to the point of the muffler. Anything after the muffler is pretty much just for sound (with the exception if you were to reduce to something ridiculous like 1.5" pipe or something lol).

    But the idea of a crossover, be it H-Pipe or X-Pipe, is to balance the flow going into the muffler or mufflers. The way V style engines work, you basically have two engines. In the case of the V8, a 4 cylinder engine on each side. Each side of th engine has it's own set of exhaust valves that are pumping at separate times. And, with all engines being different, one side of your engine might be flowing a little more exhaust than the other. So what the crossover does is balance that exhaust out to both sides of the exhaust system so that you don't have say 60% of your exhaust going through the right side and 40% going through the left side.

    Now, there are two different types of mufflers. There are baffled/chamber mufflers (Flowmaster, Thrush, ect. This is the standard style of muffler) and then there are straight through mufflers which instead of using a system of chambers, all it is is a corrugated piece of pipe running through the muffler from inlet to outlet that has some form of packing material all around it to muffle the sound. Hooker Maximum Flow mufflers are a great example of this style of muffler.

    So, if you think about it, the straight through design of mufflers for dual in/dual out mufflers is ALMOST like doing a true dual. The only difference is really that the dual in/dual out straight though style muffler doesn't quite have the same flow that two completely separate and individual mufflers would.

    Now, to reconnect this to the idea of an H-Pipe, if you were using a chamber style dual in/dual out muffler and you used an H-Pipe, it wouldn't do much because all the exhaust is mixing back together anyway and slowing down in the muffler. But if you used and H-Pipe with a straight through style dual in/dual out muffler, then each inlet of that muffler is keeping the exhaust separate from the other inlet and your balanced flow is still being maintained.

    I guess a simplified version of what I'm trying to say is, when installing crossovers, you want to install them as early on in the exhaust system as you can to get the most efficiency out of them (ideally if you have cats, right after the cats/last O2 sensor). Could a chamber style dual in/dual out muffler act as an H-Pipe? Theoretically, yes I guess so, but its so late in the exhaust system when you get to the engine wouldn't even be recognizing the balanced exhaust flow.

    And, as far as sound goes, crossovers actually help quite down the exhaust system. As far as the mufflers, they really do vary from muffler to muffler. A lot of the straight through style mufflers are typically a bit more muffled than the camber style mufflers because of the different sound dampening techniques that they use. A lot of them are starting to incorporate resonators into the mufflers as well which help out a whole lot too. Here's a couple of charts that you can take a look at of some more popular mufflers to get some ideas. The second chart is loudness of the mufflers in decibles.

    http://www.qsl.net/st0f/mufflers.htm

    Sorry for such long responses too, btw. I'm about to have my exhaust system done on my truck, and I actually did a lot of calculations with my Fluid Mechanics professor at Texas A&M and we figured out some pretty good information about what works best and things like that. So I've got a pretty good grasp on exhaust flow now lol.
    Last edited by c_m_chance; 05-01-2010 at 02:22 PM.
    MY LUG NUTS REQUIRE MORE TORQUE THAN YOUR RICER MAKES! :sign0011:

    2004 Silverado 2500 "Judas"
    Crew Cab and Short Bed
    6.0L Vortec
    Diablo Predator
    True Dual Exhaust: Hooker MaxFlow Mufflers and X-Pipe
    Drop-In K&N Air Filter
    Alpine Stereo System: iDA-x303 Deck, SPS-600 Front and Rear Speakers, KTP-445 Amplifier

    Future Upgrades Include:
    Cosmetic/Other: Spray-In Bed Liner, HID head lights, Leveling Kit
    Performance: Underdrive Pulleys

  6. #16

    Default

    So, it sounds like an H pipe incorporated with a straight through design muffler would yield the most hp. awesome.
    You know anything about suspension stuff too ? lol i've started another thread over in that sub forum if you do!

    thanks again for all the help. good info.

  7. #17

    Default

    Haha! I wish I knew more about suspension than I do. I know my old 86 that I had, I got the suspension professionally done and it was absolutely AMAZING how well my truck hooked up after that! Cars that I wasn't able to get off the line before, I was able to completely leave behind all from suspension adjustment and tuning. Whatever that guy did to my truck, it was awesome! lol
    MY LUG NUTS REQUIRE MORE TORQUE THAN YOUR RICER MAKES! :sign0011:

    2004 Silverado 2500 "Judas"
    Crew Cab and Short Bed
    6.0L Vortec
    Diablo Predator
    True Dual Exhaust: Hooker MaxFlow Mufflers and X-Pipe
    Drop-In K&N Air Filter
    Alpine Stereo System: iDA-x303 Deck, SPS-600 Front and Rear Speakers, KTP-445 Amplifier

    Future Upgrades Include:
    Cosmetic/Other: Spray-In Bed Liner, HID head lights, Leveling Kit
    Performance: Underdrive Pulleys

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