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Discussion Starter #1
I ran an ebay header for years until the rest of the system rusted beyond repair. I replaced the system with all 2.5 inch stuff and the rasp is unbelievably bad above 1/2 throttle. I have a Magnaflow spun universal 8" x 4" cat and 22" resonator and a flowmaster 50 series 3 chamber SUV muffler. The tone is damn near exactly what I wanted. Deep and mellow. The volume is almost twice as loud as I was anticipating and the rasp is horrible.

I'm thinking that a standard honeycomb cat may be a solution, as it will be larger and should slow the flow down so I'm not overloading the resonator.
Or I could bottleneck the the flow to 2.25 somewhere along the way.
Or I could add another, smaller, resonator to the existing lineup.
Or I could replace the muffler with something different.


I am not concerned with performance. The current setup was a failed attempt at creating a decent sound on a really tight budget.

What do you guys think I should do to fix the rasp? Replacing the entire system is not going to happen, even if the GB on Stromung would be the best solution lol. Just don't have the money for it.
 

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Vibrant ultra quiet. My exhaust tone has gone down about 40%. I had some rasp and it was quite loud even driving normally. Now it has a clean and modest tone. I had a magna 22" res, and there is no comparsion. I have a nismo header and megan dual tip exhaust.
 

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Discussion Starter #4
Vibrant ultra quiet. My exhaust tone has gone down about 40%. I had some rasp and it was quite loud even driving normally. Now it has a clean and modest tone. I had a magna 22" res, and there is no comparsion. I have a nismo header and megan dual tip exhaust.
Cool man, thanks. Think I should straight up replace the Magna or try to shoehorn in the Vibrant and run two resonators?
 

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funny as that sounds
its true
my experience too


4 exhaust systems later
stock
obx
and 2, 2jr systems

2 different resonators
and cats

my learnings
yay vibrant

but a ceramic cat [even race cat]
does wonders
even this worked


ceramic coated header


or wrapped exhaust


all helps

you can also encase muffler and resonator
and wrap the exhaust pipes
if you don't wish to change parts
https://www.heatshieldproducts.com/automotive/exhaust-and-header-wrap

also the quality of your rubber hangers
affects resonance and thus rasp

mine ended up this way
ceramic coated header, magnaflow 3" ceramic cat
na



and turbo
wrapped exhaust and same cat


use the thickest steel exhaust piping possible
avoid the really thin stuff

high quality ss has better thermal and resonance factors
and is preferred

good luck
hope at least some of this helps

honestly it took a lot of experimentation

now built in, to the later 2jr exhaust systems

easier just to buy one
thats for your next time
imo
 

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Discussion Starter #7
thats for your next time
imo
Thanks for the advice Barry!!
In your opinion, if I were to replace just one component to make it more quiet, should I replace the resonator or the cat? Looking at the Magnaflow 91006 or Vibrant 1141.
 

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With cars, everything is a compromise, if you want it quiet, you have to run a very restrictive exhaust, if you want high mileage, you have to tune, and run at low RPM's, and sacrifice performance. if you are willing to listen to the sound of ten thousand angry bumble bees, you can have a fast vehicle. Or, you can get your performance with power adders, N2O, Turbo, or Supercharging. It really depends on what you are willing to lose to gain the performance. Our 4 cylinders love to breath freely, both on the intake and exhaust side, anything that smooths out and quiets these areas will affect performance. Cold air intakes are good for a few ponys, wide open exhaust as well. Then you get into the drivability end of things. Are you willing to gain a few horsies at the expense of not being able to use your rear view mirrors? cut the balance chain... I regretted cutting mine until I had my whole build done by 2J, with the crank and everything balanced I am back to being able to use the mirrors. Keep in mind, I dont have the same goals as Yogi, I wanted my car to be a comfortable daily driver that would embarrass pretty much anything that would want to pass me, and still be a joy to drive the 6 hours to the beach from my house. To combat Rasp when I was NA, I had a High Flow cat welded in, a resonator, and a magnaflow (later, a flow master) muffler, This did a great job, no rasp, but it was still loud. Now, with a cat, and 2J side exit, I am not much louder than most mustangs on the road. It has been said that a turbo is the best muffler out there, and I believe it to be true.
 

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Discussion Starter #10
With cars, everything is a compromise, if you want it quiet, you have to run a very restrictive exhaust, if you want high mileage, you have to tune, and run at low RPM's, and sacrifice performance. if you are willing to listen to the sound of ten thousand angry bumble bees, you can have a fast vehicle. Or, you can get your performance with power adders, N2O, Turbo, or Supercharging. It really depends on what you are willing to lose to gain the performance. Our 4 cylinders love to breath freely, both on the intake and exhaust side, anything that smooths out and quiets these areas will affect performance. Cold air intakes are good for a few ponys, wide open exhaust as well. Then you get into the drivability end of things. Are you willing to gain a few horsies at the expense of not being able to use your rear view mirrors? cut the balance chain... I regretted cutting mine until I had my whole build done by 2J, with the crank and everything balanced I am back to being able to use the mirrors. Keep in mind, I dont have the same goals as Yogi, I wanted my car to be a comfortable daily driver that would embarrass pretty much anything that would want to pass me, and still be a joy to drive the 6 hours to the beach from my house. To combat Rasp when I was NA, I had a High Flow cat welded in, a resonator, and a magnaflow (later, a flow master) muffler, This did a great job, no rasp, but it was still loud. Now, with a cat, and 2J side exit, I am not much louder than most mustangs on the road. It has been said that a turbo is the best muffler out there, and I believe it to be true.
I debated doing the BSR when I replaced the headgasket but decided against it. It is just a DD. It is odd that you had a HF cat, res and flowmaster and had no rasp. I have the same thing and such awful rasp. I have to conclude that its the resonator not working like it should, or is at a distance away from the exhaust valve opening that happens to be an optimal wavelength for the rasp frequency. Gonna go with the Vibrant and see how it goes.
It sucks cause I had the same-ish header, muffler and HF cat on my Neon and it had zero rasp, even without a resonator. And before you spit coffee all over your monitor, the Neon was no where near stock and a blast to drive. Still miss it.

Anyway, thanks for the opinions guys! Such a great community.
 

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The cheapest option to try for you would be to wrap your exhaust, ( as mentioned already), as far as possible from the header back. It will be a little more elbow grease but you will not break the bank trying different exhaust modifications that may or may not work. I have mine wrapped through the midpipe and don't really notice the rasp.
 

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I debated doing the BSR when I replaced the headgasket but decided against it. It is just a DD. It is odd that you had a HF cat, res and flowmaster and had no rasp. I have the same thing and such awful rasp. I have to conclude that its the resonator not working like it should, or is at a distance away from the exhaust valve opening that happens to be an optimal wavelength for the rasp frequency. Gonna go with the Vibrant and see how it goes.
It sucks cause I had the same-ish header, muffler and HF cat on my Neon and it had zero rasp, even without a resonator. And before you spit coffee all over your monitor, the Neon was no where near stock and a blast to drive. Still miss it.

Anyway, thanks for the opinions guys! Such a great community.
I was using an XS Power 3 piece header/test pipe, with a custom (muffler shop) 2.5 inch exhaust, had the cat welded in the front section of pipe right after the header, the biggest resonator that would fit (20") then to the flowmaster muffler, I couldn't really tell too much difference between the Magnaflow, and the flowmaster as far as noise or tone, was concerned, two different technologies, but both did the same job. The only reason I went with the flowmaster was that the magnaflow kept breaking at the exhaust inlet side and I was tired of getting it welded.
 

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I debated doing the BSR when I replaced the headgasket but decided against it. It is just a DD. It is odd that you had a HF cat, res and flowmaster and had no rasp. I have the same thing and such awful rasp.
Anyway, thanks for the opinions guys! Such a great community.
Rasp may also be dependent on what you are willing to hear. as for the BSR, I had to change my oil pan out after an interstate incident, and decided to do mine while I had the oil pan off. I almost immediately regretted it, for the vibrations. They weren't bad, but were bad enough that I thought about getting another timing chain kit and reactivating them. for me, the vibration was too much for a daily driver. Now that I have a 2J knife edged crank and the internals are balanced, its no longer an issue. If you are only going with factory rev limit, I would counsel anyone against doing the BSR. Once you get to where you want to rev higher, its a must.
 

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Interesting that this subject came up. Though I haven't done the exhaust for the B15 yet, I'll relate my experiences with the Honda Wagovan I built and daily drive, and you can draw your own conclusions...

After my turbo D16 install, I took the Wagovan to the local Midas shop for a header-back exhaust install. Four hours later the backwards-hat wearing dufus from the back shop came out and said he couldn't figure out how to build a two and a half inch system for the car. By this time i was pissed off, so I stopped by Autozone (which, coincidentally, is 2 blocks down the street) and bought a flex pipe, some straight pipe, some bends, and two Thrush glass packs. I went home and built my own exhaust system in about six hours, and it's nice and QUIET... no rasping, very mellow, and it's just loud enough to let you know it's running when you jump on it. Secret here was to butt the two glass packs together with a short connector pipe in between. Also helped that I have a welder and could weld it all together. Not saying this is the answer to ALL the rasping problems you might encounter, but the car flows free, is quiet, and it still gets 38MPG on the highway.

The QR build might only get one glass pack, since we're going on track with it, but it'll be quiet enough to pass the DB meter trackside and not set the alarm bells off...
 

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I had mentioned dual resonators to my exhaust people, and they were firm in stating that one longer resonator was better than 2 shorter ones. the setup they hooked me up with I had no complaints with, it had a deep rumble that I wasn't embarrassed to let sound off around other imports. They did a great job for me.
 

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It is odd that you had a HF cat, res and flowmaster and had no rasp. I have the same thing and such awful rasp.

welcome to chaos theory and resonance

1st
what is rasp

well best i could find
its destructive resonance of a reed like structure

a vibration that literally shakes the whole pipe

like a bad note on a clarinet
where the reed flutters

yup
rasp is tail pipe flutter
or so say the physicists


thus wrapping, pipe length and change of pipe thickness
as well as
the ratios of valve to resonator and muffler to tailpipe volumes and lengths

alter this overlapping cyclic phenomena

people like the mad hungarian with long experience
almost invariably get the ratios of pipe length, volume and such right

because flutter frequently slows flow
interferes with power and destroys parts
like and similar to, wheel hop

tuned for power also means tuned pipes
at least they are aware of it

and choose ratios that deliver good power
thus no flutter


some short drag racing pipes may use this frequency to empty the combustion chambers
they may not have rasp but they sound terrible
[listen to stevenspecs 12 sec pass]

best i can figure out
imo

simple examples

thick pipes short lengths
solid mountings

loud but no rasp


well mounted with cat


huge resonator on long thick ss pipes
look under car almost touches the ground


coupled with big muffler
 

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The Wheel Ninja
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Apexi WS2 or vibrant street power muffler will solve all those issues.
 

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Another thing to check that would create more rasp, is to check inside the exhaust pipes at the flanges. On the lower quality exhausts you would see a small gap between the ID of the flange and the OD of the pipe. This would create, (as Barry mentioned), a reed like resonance and add to more turbulent flow. I believe the higher quality exhaust manufacturers either grind those edges down or are more careful in the welding process.
 

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last na system i used
worked well imo
quietest na system too

long solidly connected collector
header ceramic coated




short solid side exhaust
much quieter
no rasp



summery

ceramic coated header
well mounted , short thick steel piping
large muffler and resonator
ceramic cat

no rasp, excellent power and sound
 
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