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Shkreet Car Interior Deshibul Levelsh

 
Old 07-03-2018, 04:01 PM
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Default Shkreet Car Interior Deshibul Levelsh

Fighting a problem in my street car build.

It's OBSCENELY loud inside at the normal BP "node" RPM points. ~1500 and again in the 3000-4500rpm range. We're talking 115-120db.

Exhaust is RB front to back. Header, midpipe, Power Pulse muffler. Vteckiller measured decibels on a phone app, so take the actual numbers with a grain of salt. The frequencies that are strongest are at nodes that we would have expected the HUGE resonator in the RB midpipe to cancel. Rubber hangers.

We initially chalked most of it up to the header and oil pan contacting the subframe due to motor mount issues. I swapped mounts since then and have miles of clearance, but the interior volume level is still completely out of control. Car has no soft top, hard top is bolted on with brackets, not latches.

Anyone else running this same exhaust setup that could ballpark decibel level for me? Any similar experiences fighting noise? Car is pretty subtle outside, the interior drone is just horrid. I had a similar issue with a full FM exhaust on our original MSM. Whisper quiet outside, horrendous headache-inducing drone inside, though wasn't quite as bad as this car.
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Old 07-03-2018, 04:37 PM
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turbo owners don't have these dumb problems
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Old 07-03-2018, 04:39 PM
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Originally Posted by concealer404 View Post
Fighting a problem in my street car build.

It's OBSCENELY loud inside at the normal BP "node" RPM points. ~1500 and again in the 3000-4500rpm range. We're talking 115-120db.

Exhaust is RB front to back. Header, midpipe, Power Pulse muffler. Vteckiller measured decibels on a phone app, so take the actual numbers with a grain of salt. The frequencies that are strongest are at nodes that we would have expected the HUGE resonator in the RB midpipe to cancel. Rubber hangers.

We initially chalked most of it up to the header and oil pan contacting the subframe due to motor mount issues. I swapped mounts since then and have miles of clearance, but the interior volume level is still completely out of control. Car has no soft top, hard top is bolted on with brackets, not latches.

Anyone else running this same exhaust setup that could ballpark decibel level for me? Any similar experiences fighting noise? Car is pretty subtle outside, the interior drone is just horrid. I had a similar issue with a full FM exhaust on our original MSM. Whisper quiet outside, horrendous headache-inducing drone inside, though wasn't quite as bad as this car.
Originally Posted by 18psi View Post
turbo owners don't have these dumb problems
Oh?
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Old 07-03-2018, 04:40 PM
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when you build major h8ter vibr8er, you must embrace the vibr8ions
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Old 07-03-2018, 04:42 PM
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Decibels, not vibrations. Why is this so haaaaarrrrrrdddd?

This is an exhaust drone issue i/we am/are reasonably sure. I can put stock engine mounts in it, but i've swapped engine mounts enough times in the last month or so that i'd rather shut my nether regions in a door than do it twice more.
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Old 07-03-2018, 04:47 PM
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I've driven many rs/rb/fm cars and none were anything like you're describing. Biggest ugly noise inducing thing was no cat. Made the ugliest sound ever
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Old 07-03-2018, 04:51 PM
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Ok well... if anyone is reading this and currently has any similar setups, would they mind taking an unscientific measurement with their phone? I find it somewhat unlikely that i've "won" this lottery twice and nobody else has.
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Old 07-03-2018, 04:53 PM
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hmm. On my naturally aspired 1.8NA, I've got jr header --> stock cat --> non-resonated rb sport midpipe --> single power pulse muffler. Mazda comp motor mounts if it matters. It's quiet. I've also had a resonated test pipe instead of the stock cat and the car was still quiet..like stock car quiet.
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Old 07-03-2018, 04:57 PM
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Would you mind downloading some sort of app and measuring interior cruise db for me at some point? I would greatly appreciate it.

"Stock car quiet" is pretty much what i was expecting with this setup.
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Old 07-03-2018, 04:59 PM
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Originally Posted by concealer404 View Post
Ok well... if anyone is reading this and currently has any similar setups, would they mind taking an unscientific measurement with their phone? I find it somewhat unlikely that i've "won" this lottery twice and nobody else has.
are you catless?
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Old 07-03-2018, 05:02 PM
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Originally Posted by 18psi View Post
are you catless?
Yes. It's an RB setup front to back. RB does not make a catted system for NBs. So.... if you've been in/driven an NB with an RB setup front to back, you've been in/driven a catless RB-equipped NB.
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Old 07-03-2018, 05:12 PM
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yup
catless = crap
catted = much better
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Old 07-03-2018, 05:14 PM
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Now you're backtracking and being confusing. You said you've driven many RB cars and didn't experience this. The car is super quiet outside and sounds great.

I'm after hard data measured unscientifically with phone apps, as well as anecdotes with similar systems. You have the anecdotes and say it was quiet and good. Got it, will put in spreadsheet. <3
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Old 07-03-2018, 05:17 PM
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I'M POSTING COLD HARD FACTS!!!

want me to bust out technology and post datalogs with sharpies and masking tape?


better check yoself
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Old 07-03-2018, 05:18 PM
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Mmmmmmm the logging kit!
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Old 07-03-2018, 05:18 PM
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last rb header car + catted rs3 exhaust I drove sounded real nice, bot in and out
then we swapped out the catted midpipe for catless
it sounded like you in the bathroom after you ate a bucket of cheese curds
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Old 07-03-2018, 05:19 PM
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dunno how you had this problem with the msm. I had both the fm old school and fm new school exhausts on my msm, sounded great with both

catless egay downpipe too
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Old 07-03-2018, 05:21 PM
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I think we're still confused. I don't have a single issue with exterior volume. It's QUIET (easily as quiet as the MSM was outside). I don't have a single issue with the KIND of noise it makes, it sounds GREAT. Zero fart and gross **** you normally associate with a catless car.

My ONLY issue is with interior drone/decibel level. The noise i hear inside is a good noise, there's just WAAYYYYYYY too much of it. Got me, sugar?
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Old 07-03-2018, 05:23 PM
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just route exhaust into interior. it will muffle and baffle
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Old 07-03-2018, 05:24 PM
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Yooooooj resonator!
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