March 29, 2024, 06:42:13 AM

Author Topic: Dual 3" Exhaust Escapade  (Read 16987 times)

Offline Cobranut

Re: Dual 3" Exhaust Escapade
« Reply #15 on: May 18, 2016, 11:29:16 AM »
The bullets are after the X-pipe, just ahead of the rearend crossmember.
1995 FD, 7.0 Liter stroked LS3, T56, 8.8, Samberg kit.

Offline XLR8

Re: Dual 3" Exhaust Escapade
« Reply #16 on: June 30, 2016, 10:06:17 PM »
Video of the completed exhaust I posted above.  Sounds perfect for my needs.

http://youtu.be/SVAIYhgpohI
94 MB Base...416 LS3 Stroker......Build Thread

Offline neil_se

Re: Dual 3" Exhaust Escapade
« Reply #17 on: July 01, 2016, 08:39:51 AM »
That's quite possibly the best LS exhaust I've ever heard.

Offline Gunnytron

Re: Dual 3" Exhaust Escapade
« Reply #18 on: July 01, 2016, 01:54:02 PM »
Sounds nice and deep  8)
http://www.norotors.com/index.php?topic=12880.0
FD, LS1 running 220 3.90 Trickflow heads, Comp Ultra-gold Arc 1.72 Rockers, 7.550 BTR Pushrods, BTR Stage II NA Cam 227/234 .614"/.576" 113+2, ARP Head Bolts, BTR Platinum Springs, Ported FAST 90, NW 90mm TB, FAST 60lb Injectors, Textralia Clutch/Flywheel, T56, Cobra 8.8, 31 spline, trac-loc 3.55 Diff, Holley HP EFI, Racelogic TC.

Offline kinger

Re: Dual 3" Exhaust Escapade
« Reply #19 on: July 14, 2016, 10:48:18 AM »
New Videos at the beginning of the post

New setup is dual dynomax bullets and dual dynomax ultraflows

Cruising interior dB went from 100 to 85. It sounds quite a bit louder in person as always

Overall I am very happy



http://youtu.be/mMhsR2ohNyo

Lol, hit a corner a little faster than expected.


This cracks me up when you stab the throttle and start screaming! LOL  I did the exact same thing in mine the other (on closed course conditions of course) let her stretch her legs in 4th/5th gear and was screaming at the intensity of how fast it picked up mid triple digit speed LOL  You have the balls to record on video, well done HAHA
93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Offline kinger

Re: Dual 3" Exhaust Escapade
« Reply #20 on: July 14, 2016, 10:58:29 AM »
So who is this V8rx7 Anthony guy and how do I get a hold of him?  You went to 85db cruising in 6th at what speed?  I need that I am at 95-100db at 75mph and its worse when at 55-60mph.  I like the idea of dual 3" with the X vs the single 3" now.  I would love 85 or less.  Thanks
93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Offline Tictakman

Re: Dual 3" Exhaust Escapade
« Reply #21 on: July 15, 2016, 08:29:47 PM »
kinger, whts ur current exhaust?

Offline kinger

Re: Dual 3" Exhaust Escapade
« Reply #22 on: July 16, 2016, 05:20:53 PM »
JTR 1-7/8 to 3" single through a vibrant ultra quiet resonator and a vibrant 15" long oval muffler. Sounds amazing just can't take the drone.


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93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Offline kinger

Re: Dual 3" Exhaust Escapade
« Reply #23 on: July 16, 2016, 05:43:26 PM »


Also wanted to add a cat do you think 1-3" cat is enough?  Or do I need to use two before the merge?


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93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Offline halfspec

Re: Dual 3" Exhaust Escapade
« Reply #24 on: July 17, 2016, 06:19:18 PM »
I like the idea of dual 3" with the X vs the single 3" now.  I would love 85 or less.  Thanks

I'm not going to say it's impossible, but I'll go ahead and say it's probably not going to happen unless you're willing to go with chambered mufflers and in-line cats. Lowering the volume on a dual exhaust is exponentially more difficult vs a single exhaust. Ask Josh / XLR8 above about volume. The dual exhaust he bought from me started out being loud enough to make your ears ring after 15 minutes. Seriously, if you think the single you're running is loud, I don't think you would have been able to get within 100ft of a 3" true dual exhaust on one of these cars. It is shockingly loud. Even with a muffled x-over I doubt Josh would describe it as quiet ;)
If you're truly after a quieter setup I'd recommend sticking with the single exhaust and adding quieter components.

Lane




Offline kinger

Re: Dual 3" Exhaust Escapade
« Reply #26 on: July 17, 2016, 06:59:28 PM »
Actually the sound volume is awesome it's the drone at 95db while
on the highway that stinks.  A super turbo from dynomax is not recommended they said it will choke the motor, the VT will probably tink at idle, Borla multicore XR1 is the only ones saying it will eliminate the drone. Any other ideas?  I will keep the single but have to get creative on a muffler that won't choke it off to bad. 


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93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Offline halfspec

Re: Dual 3" Exhaust Escapade
« Reply #27 on: July 17, 2016, 09:13:34 PM »
Actually the sound volume is awesome it's the drone at 95db while
on the highway that stinks.  A super turbo from dynomax is not recommended they said it will choke the motor, the VT will probably tink at idle, Borla multicore XR1 is the only ones saying it will eliminate the drone. Any other ideas?  I will keep the single but have to get creative on a muffler that won't choke it off to bad. 


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I'm no expert in exhaust design, but if droning is your only complaint I'd be looking at resonators vs mufflers. Resonators are made to cancel out a range of frequencies based on it's physical design. Mufflers can be effective resonators too based on their design, but generally you can do a better job eliminating a known drone frequencies dealing with a basic resonator. You've got a resonator in-line with your system, but it's not really a one size fits all piece. They're very variable based on their design.

If I were in your shoes I'd swap in the straight pipe and monitor the car after. With the straight pipe you set yourself at a easier starting point to fix the problem. Additionally, with a change in the system you'll most likely see the drone move vs rpm / speed. Once the exhaust is straight through I would then identify the resonant frequency making all the racket with a real time analyzer (RTA) (basically a calibrated microphone paired with computer + software that listens to noise and graphs it). Once the resonant frequency is identified I would read up on resonator design and design or buy a resonator designed to change the specific resonance of YOUR system to eliminate the resonate frequency group causing the problem.

There are plenty of other ways to skin the cat, but in my experience you're dealing with an industry that predominately won't do this type of work to accurately measure and attack the problem based on quantifiable data. You're far more likely to run into people who'd rather shoot from the hip and sell you a solution that will eliminate your "drone" without even taking the time to get the specifics about your drone.

Lane

Offline Cobranut

Re: Dual 3" Exhaust Escapade
« Reply #28 on: July 17, 2016, 09:37:15 PM »
All I can say is the 3" duals that are on my car have no offensive drone at any RPM, and it's one of the quietest true performance exhaust systems I've ever heard, especially considering the state of tune of my motor.   8)

I don't know how healthy of a motor you're running, but a single 3" is going to strangle anything over 500 HP or so.
1995 FD, 7.0 Liter stroked LS3, T56, 8.8, Samberg kit.

Offline kinger

Dual 3" Exhaust Escapade
« Reply #29 on: July 17, 2016, 11:36:47 PM »
Ok the enginerd got me, busted out the spectrum analyzer and found my issue freq. I did three tests to isolate the offending frequency and found about a 10db increase at 100 hz.

Here is the results in 6th gear going 60mph at 1500 rpms where the drone is the worst. Look at the yellow line and how it makes a step change after 120 hz.


Now here is the same instance but in 5th gear at 60 mph and 2000 rpms. Notice the hole between the peak 80-120 hz bar it's almost 10db full difference. If you understand sound 10db is a very significant jump.


Just for fun I hit the interstate at 70 mph in 6th around 1800 rpms. The drone is not nearly as bad as 60 mph the graph shows it basically splits the difference.



Now if you reference the formulas and charts floating around on the hemoltz resonators you can see I need like a 33" J pipe to effectively cancel out 100hz.



Not sure how I would fit that in there but it's cool to have a possible answer.


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93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights