Quiet Performance Mufflers/Exhaust

Discussion in 'Technical' started by Phil, May 11, 2016.

  1. Crazy Larry

    Crazy Larry Member

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    (Retracted)
     
    Last edited: May 12, 2016
  2. groberts101

    groberts101 Member

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    Everything you just mentioned lines right up with all that I spent 15 minutes typing on my phone in my last reply. You can go with a bigger case(I've run the 70 series and while they are most cerainly quieter.. they are big AND heavy).. though I'm not sure how much room is available since I haven't built an exhaust yet for my/these cars yet. Will a 19"+ case even fit?

    Also.. running straight thru magnaflows in a longer case won't make a world of difference here either. I've seen others try and they are pissed about the wasted money for marginal sound reduction.

    BUT.. none of that will fix the obvious underlying problems you have going on here. Hangers should be more compliant.. tailpipes should extend slightly past the rear valance.

    Also consider that just because mustang or corvette mufflers can support those higher power levels.. doesn't mean they will be on par with a free flowing aftermarket pieces. OEM has much tighter sound constraints and simple physics means quieter ALWAYS costs power. This is part of the reason many will nix the OEM stuff in their favor for increased output.. not just about the cool sound. Of course none of that matters if sound reduction is much more important than max power output.
     
  3. Crazy Larry

    Crazy Larry Member

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    I need to retract my previous post. I don't think 19" mufflers will fit a Maverick.
     
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  4. stumanchu

    stumanchu Stuart

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    I wonder if sheetrock would block sound better than plywood? Cover the edges with duct tape so chalky crumbs dont go everywhere? Just thinking out loud.
     
  5. Crazy Larry

    Crazy Larry Member

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    Uhm...no.
     
  6. 71Mavrk

    71Mavrk Member

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    It sounds to me (ha) like you just need to junk this whole set up and start over. If you can afford it. Homemade headers, 2.5 to 2.25 pipe, bad hangers ..... I would keep the Magnaflows though.

    Consider getting the correct headers. Having the proper size pipe. Have it suspended properly.

    I was driving yesterday with the window down the whole time and it was only loud when I was hammering it. Otherwise, noticeable but not obnoxious. With the windows up, not loud inside. This is with shorties, X pipe, 2.5, out the back, 347.

    Micah
     
  7. groberts101

    groberts101 Member

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    Micah may be right that replacing would be better than fixing. I made the assumption that "homemade headers" meant "modified off-shelf headers".. not "scratch built". Not many build custom pieces because the component costs alone can easily exceed the cost of shelf headers. But without pictures and engine build details all we can do is speculate.

    Personally speaking, unless this motor is making pretty decent power at moderate to higher rpm's(bigger cam with decent heads).. and/or you have lots of crimp bent twists and turns causing substantial flow losses?.. I wouldn't be shying away from running 2.25" piping at all. It can help build torque for smaller motors and makes more power/flows more than many may realize. 2.5" pipe sizes are better for setups making WELL over 300 flywheel horsepower.. up to about 500 in well designed systems. Guys running dual 3" setups on moderately powered/compression ratio short stroke 302's are just killing torque and trading it away for that cool sound. Slightly larger pipes can also help systems that have lots of twists and turns with muffler shop type crimp bends too. Otherwise mandrel bent pipes can allow you to stay smaller while still allowing sufficient ID sizing in bends yet help build greater average torque for street cars due to their greater velocity capability. Velocity is what helps build torque on the street.. NOT outright flow levels to increase peak horsepower numbers. Street motors are all about average power.. not just peak power.

    At the very least you could learn something by trying to quiet down what you've already got. Otherwise new parts could be just as loud.. maybe even louder.. if you don't understand the physics involved with building a decent sounding system that doesn't turn your cars underbody and its various cavities into a great big resonance inducing tuning fork. Many have made the same mistakes and wrongfully assumed that it was the mufflers fault. Not very prudent to just toss money at issues you don't understand or you'll just be wasting them on bandaids without attempting to heal the underlying wound.

    I've said about all I can say on the matter.. horses to water.. making them drink.. and all the rest. Good luck with it.

    EDIT; if you don't mind some extra reading.. much of this was already said and accomplished.. here.

    http://mmb.maverick.to/threads/the-great-flowmaster-super44-drone-experiment-of-2012.90411/
     
    Last edited: May 14, 2016
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  8. tbirdz12

    tbirdz12 Member

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    Last edited: May 17, 2016
  9. Pony Express

    Pony Express Haul'in @**

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    I would agree concerning Borla; I have them on my Cobra...
     
  10. rotorr22

    rotorr22 Member

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    Borla's here as well. Bought them based on their reputation for quality and engineering.
     
  11. groberts101

    groberts101 Member

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    I have to call poo-poo on that magazine article posted above simply due to the advertising, sponserships and cash tossing bias being added into the mix. And the simple fact that they are implying that mufflers will make more power vs an open exhaust is downright silly because they clearly didn't use collector extensions to retune for optimum collector length. Race cars only use mufflers due to sound mandates and even then they will usually try to incorporate them into the header/collector as a continued part of the collector length tuning process. And I won't even get into the slight but relevant tuning differentials required to accurately compare a higher back-pressured chambered muffler to a true straight through design.

    So, a straight thru perforated core muffler is a straight thru perforated core muffler(void of splitters and such) and the power is nearly the same between all of them due to the inherent design and physical similarities. Only thing that changes to some small degree, besides the in/out layout(which SHOULD be considered into the final result), is the tone which is somewhat dependent of the core size, design, and specific packing/s used in its construction. Of course some of those things can affect power output, but it sure as hell ain't anywhere near the order of 10 horsepower for a straight through design.. unless you don't mind some advertising based spins being used against you and twisting your arm to sell you shiny "super mufflers".

    Bottom line.. look at the bigger picture.. listen to real world examples.. at least listen to some sound clips.. and apply some physics into it(center to center designs shouldn't be the deciding factor when you're forced to run offset/offset, right?) by relating and comparing it to the specific combination of parts YOU have. This stuff is just so subjective and the engine combination alone makes such a huge difference for the final results for both power and sound(decibels AND tone). I hear cars all the time that people get surprised at how different they sound when running the EXACT same mufflers. Even seen them pull up side by side in the parking lots to have a closer listen. And of those combos some even have a nearly identical header designs(size/layout) and exhaust pipe layout. The ones that are even more remarkable are the ones running entirely different engine combinations but using the same mufflers to sound completely different than one another.. like a 2V OHV compared to a 4V OHC motor.. or mild cammed/dual plane vs a big cammed/single plane combo. Offer people a $100 bucks to guess what the differences were and you'd never end up paying the bet.

    I myself will be running Hooker aero-chambers as well. Not because they are superior in output to other straight through designs but simply because they sound a bit different than a lot of the other typical designs being made in cookie cutter fashion. If I were naive enough to believe all the advertising that Hooker puts out?.. they would have me believing that they flow more than a straight pipe of similar dimensions. But luckily I realize there is some money at stake and to keep trusting in the physics of the world I live in. lol
     
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  12. Crazy Larry

    Crazy Larry Member

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    Yeah, most of those magazine articles are sponsored by Advertising money.

    And yeah, I've always found it hilarious when a muffler company claims that their muffler "flows better than a straight pipe". Let's see now...Let's put baffles/restrictions/obstacles/ in the path of the exhaust gases and they're going to flow better?? That defies basic physics. Pressure takes the path of least resistance...always.
    Whether it's electrical current, air pressure or hydraulic pressure, it's going to take the lazy way out -- the path of least resistance. I do think the Aerochamber mufflers sound great, but at the end of the day, it's still a muffler.

    The straight-thru, perforated tube mufflers (glass packs) probably flow the best, but that perforated tube is creating turbulance, which will not flow like a straight pipe. They also don't always sound the best -- it depends on the engine and the rest of the exhaust system. I like 'em on '40s & '50s cars.
     
  13. rotorr22

    rotorr22 Member

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    C'mon, groberts. The next thing you'll be calling poo-poo on will be Car Craft's 400 HP 302 with the stock GT cam:rofl2:
     
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  14. FishnRace

    FishnRace Jamie

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    I have the Hooker MAXflows with Crites headers behind a 351 and 2 1/2 mandrel bent straight out the back. These had the best idle and 2000 RPM decibel numbers (lowest) AND one of the highest WOT decibel levels (flow!). I can't say it's quiet at 3K+ on the highway with the 4.11s, but the decibel numbers say this is one of the best performance mufflers.
     
  15. groberts101

    groberts101 Member

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    I've heard quite a few of those mufflers and they are LOUD as hell at WOT. Otherwise, it's just a cookie cutter design like all the rest. Would use them on a higher effort motor but surely not on something that someone was trying to tone down.

    And while max decibel numbers can paint a trend in outright flow capability(freer flowing straight through perforated core vs more restrictive chambered designs).. it is not the be all end all for rating a mufflers flow performance. Since it is intended to be a sound attenuation device to begin with.. the overall design of the muffler and the packing material/s used(some type last longer than others) can make a substantial difference in the final sound output at varying rpm's and can be entirely separated from the flow potential. And not all chambered designs are so far off from a straight through perforated core design since pressures can be modulated within the core itself. Smaller ID sections can increase gas speeds and drop pressures while the larger ID sections can slow speeds and increase pressures(Bernoulli's principal is also why carbs work and flow as much air as they do). So many times it is counter intuitive to the way we may think things will work as flow and pressure waves can be funny like that.

    And as I said before.. comparing a straight thru perforated core muffler to another straight thru perforated core muffler of similar dimensions and assuming flow differentials will be considerable enough to even discuss is a complete waste of time. Saturate both units on a flow bench and the numbers will be nearly identical. Anyone telling you something different is just misinterpreting the benches readings or flat out misrepresenting them because they are trying to sell you something.
     

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