6.2 Help with keeping back pressure.

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JJ f150harley

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Hi guys I need some help from y'all experienced exhaust people. I'm am putting on stainless works offroad headers with the x pipe and I have two magna packs going on as my mufflers. What I need help with is where I should have it exit in order to keep enough back pressure. Should I do lightning style, dumped before the rear axle, dumped over the rear axle, or 45 behind each tire? I don't know much about keeping the back pressure so I figured that I could get some experienced help. Thank you for the help.
P.S. Happy Thanksgiving
Jerry

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I'm not an expert but I can't recall any issues with back pressure. Theres a few people with no muffler and resonator and they aren't having issues either. With what you've listed, I think you'll be alright no matter how you set it up.
 
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Cleave

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I'm not running headers, but I am running no muffler and no resonator, haven't had any issues since I did it over a year ago, any way you go with exit style you should be fine, so it's just figuring out what your personal preference is, happy thanksgiving jerry
 

Stepside

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Back pressure will be insignificant and barely measureable for your set up.
You should not be concerned with differences needed at a Drag Strip.
You only need to decide wheather or not
you want more noise :boxed: in the cabin
by bringing the exhaust out in front of the rear wheels
or over the axle.
:sunot:
 
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NickPic83

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Dont worry about back pressure. Just pick what ever exit style suits your needs.

Dumped before axle will probably be the loudest in cab but will be great Offroad.

Dumped after axle will be slightly less loud in cab and will also be great Offroad.

Lightning style should be decent Offroad and l probably as loud in cab as the after axle dump.

Behind the rear tires will be the least volume in cab but probably the worst Offroad and destroying the tips off road is just about a guarantee.

Either decision plz post a video. I am interested to hear it. Probably sound great

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Deinonychus

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Back pressure isn't the best understanding for exhaust optimization. Exhaust velocity is what you want to optimize.
Obviously at high RPM's the volume of exhaust is much higher than at low RPM's. But the exhaust effective cross section is constant (in most all vehicles), so at low RPM's the exhaust velocity is much lower than the velocity at high RPM's.

At a cylinder exhaust valve open a pulse of gas is emitted into the the primary tube or manifold. Behind the pulse is a "vacuum" that will tend to pull the next exhaust pulse out of its cylinder.

The "low back pressure" problem occurs at low RPM's when exhaust velocity is too low to allow a "vacuum" to occur between the exhaust pulses, which aids in evacuating the cylinder combustion chambers.

Of course you don't want excessive "back pressure" at higher RPM's which will restrict the volume of exhaust gases, lowering horsepower generated.

So we search for the ideal compromise.

That said, you probably can't go wrong with any system you would typically decide on.
 
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JJ f150harley

JJ f150harley

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Thanks everyone for the help. Good to know I won't have to worry about anything. Its being installed and I get it back Monday. Then in to the exhaust shop Tuesday so I still have time to think about it. I'm leaning to the over the rear due to keeping cabin noise down and I already have lightning on my 99f150. I will post up videos of straight headers no cat and then it with the rest of the exhaust on. Thanks for the help and happy thanksgiving

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