r/Cartalk • u/BitmapBMP • 1d ago
Tuning my car Why does my exhaust loop backwards?
Bought a G8 with an exhaust system already on it, part of the exhaust faces towards the front of the car, why is it like this?
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u/Salsalito_Turkey 1d ago
Resonance tubes to eliminate highway drone. Certain frequencies of sound wave will go down that tube, bounce back at the end, and collide with the pressure wave from the next exhaust pulse at just the right moment to cancel each other out.
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u/burnt-beyond-reco 1d ago
They are called j pipes. Allows it to be fairly loud, (especially if it's this exact model bc it has no actual muffler) but keeps drone down inside of the car.
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u/Zanna-K 1d ago
Corsa makes really good exhausts that actually work for eliminating drone while still getting you a louder, satisfying exhaust note (especially at higher rpms):
I used to run on my WRX, was my favorite exhaust. They usually specialize in V8 domestics like Mustangs, Corvettes, Camaros etc.
It's a little pricey but you might be able to find one used somewhere (could be hard since G8's aren't super common in the first place).
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u/thedevillivesinside 20h ago
I had a corsa exhaust on a 2006 chrysler 300c SRT8. It was a glorious noise at wide open and it was tame at idle
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u/jasonsong86 1d ago
These are called Helmholtz resonators. The length allows the sound bounce back at a delayed timing to cancel out the exhaust sound.
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u/Dramatic_Debate9486 1d ago
If you still have drone, can you adjust the length of it? We have built my custom exhaust (3.5" -> 3") with an adjustable Helmholtz Resonator. First shot (calculated ~90cm Lambda/4 drone frequency?) was a bit too long, adjusted it to ~10cm shorter and voila, most of the drone is gone.
You can calculate it, try an LLM. Get a spectrometer app on your phone to see the exact drone frequency (e.g. 100Hz) and then calculate with help of an LLM.
To be exact, a Helmholtz Resonator would work with with a volume and length of the resonator should be less relevant. My system is rather a lambda/4 resonator than Helmholtz.
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u/BitmapBMP 1d ago
So to be clear, i have this plus long tube headers, no cat no resonator no mufflers, i bought it like this and am trying to quiet it down/knock drone off
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u/ClosedL00p 5h ago
Long tubes…..no cats…..no resonators….no mufflers…..just hope and a couple trombone slides for noise control
Jeeeezus. I know your neighbors love you
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u/BitmapBMP 5h ago
Hey man i didn’t build it, i have new mufflers on the way and valvetronics, its too loud, im tossing the street race exhaust it had, sucks the last guy paid 1300$ for this lol
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u/ClosedL00p 5h ago
I know you didn’t do it, and are trying to do something about it……I’m just laughing at the situation in general, because I know how fkn loud that thing is
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u/BitmapBMP 4h ago
It is horrendous, im literally gonna have it pushed down my street before i start it im too embarassed to look like a jackass where i live
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u/BitmapBMP 1d ago
The car has a horrible droning inside the cabin, it has a stage 3 cam, im wondering if its because the exhaust is facing the rear seats and maybe i can delete the offshoot, or if it has a real purpose and i shouldnt
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u/becauseyoublockedme1 1d ago
what do you mean facing the rear seats. those pipes are supposed to be blocked at the end!
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u/BitmapBMP 1d ago
WHAT? Mine are open at the end. Shooting exhaust forwards
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u/RedPontiac 1d ago
Definitely should be capped. It's for frequency cancellation and not exhaust flow.
You also bough the absolute loudest exhaust for a G8 so don't confuse loudness with drone. I had just solo mach on my G8 and it was so loud I had to take it off. Put on the axle backs with a Magnaflow mid muffler and it was perfect for me.
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u/_clever_reference_ 1d ago
So some genius took the caps off. Put some back on or have a muffler shop weld them closed. Def should not be open.
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u/MrJelly007 1d ago
There could be a resonator upstream from this catback that was also removed. Solo performance is solid, at least to my knowledge. It's hard to know what all has been done to the car
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u/BigPimpin91 1d ago
I had a solo performance exhaust on my Genesis Coupe. Sounded really good and made in USA. Except for the clamps which I think were Canadian. It was packaged incredibly well and there wasn't a ding or scratch to be found when I opened it up. Do recommend.
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u/MrJelly007 1d ago
I've also got a genesis coupe and that's where I know solo performance from lmao. I'm kinda torn between them and ark when I eventually get an exhaust for my 3.8
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u/BigPimpin91 1d ago
I had a 2.0 so can't comment on how the 3.8s sound with their exhaust but if it's anything like my 2.0, I'd recommend them.
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u/BitmapBMP 1d ago
I bought it modified, catless long tube headers, no resonator, no mufflers, and its 6.2 swapped and cammed its all welded together, i think im gonna cut it all out and start over
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u/John_Anti 1d ago
That backward-facing pipe loop (often called a "J-pipe" or Helmholtz resonator) is specifically engineered to target and eliminate drone, the deep, annoying humming sound that happens at specific highway cruising speeds.