Trouble with the ZL1 cat backs? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Hamadozz · 02-03-2015, 01:04 AM

hey guys

my zl1 have some small modifications that i will list below, and when i tuned it the tuner said the car is really loud and that its not supposed to sound like that. i asked him what could be the problem and he said the cat backs, and keep in mind my cat backs are stock! so did anyone have a problem with their cat backs being louder than normal with time? cuz im beginning to think that the stock cat backs gets disrupted with time!

my modifications:
Lower cranck pulley
gt9 cam
tr7 spark plugs
dynamics 850 ID injectors
stock mainfolds and JBA catless pipes (used to have ARH long tube)
supercahrge snout
roto fab CAI
93 throttle body
heat exchanger
water pump

car should easily make 570rwhp

so share with me what you guys have experienced and what you know!

unstable vic · 02-03-2015, 08:48 AM

I've seen on some other threads the inside of the stock mufflers actually coming out of the tailpipe! It looked like steel wool. There replaced under warranty of course.

ZO6 Bryan · 02-03-2015, 08:54 AM

The exhaust flaps are open at idle normally. So if you have eliminated the cats it's going to be loud. Combine that with a bigger cam that has earlier exhaust valve open point and it can get pretty loud. It quiets as soon as you drive off and the flaps in the exhaust close, doesn't it?

mrvenicess · 02-03-2015, 10:20 AM

I had the same situation but also have long tubes. I added the ADM exhaust valve controller so on start up the exhaust valve stays closed until I open it. Some have said that the packing inside the mufflers fails, mine seems to be starting, although my parts guy was of the opinion that the mufflers are just a series of bent and vented pipes inside. Haven't cut one open so cannot be sure.

Modern07 · 02-03-2015, 12:37 PM

Quote:

Originally Posted by mrvenicess

I had the same situation but also have long tubes. I added the ADM exhaust valve controller so on start up the exhaust valve stays closed until I open it. Some have said that the packing inside the mufflers fails, mine seems to be starting, although my parts guy was of the opinion that the mufflers are just a series of bent and vented pipes inside. Haven't cut one open so cannot be sure.

No it has muffler packing in stock exhaust - mine failed originally - just before the cats themselves failed

KaBoom1701 · 02-03-2015, 12:54 PM

You mod the car for additional HP and then complain about how much louder it is.......ok?

NicKey · 02-03-2015, 12:57 PM

Yes. there are issues with the material in the mufflers not staying in place on modded cars and changing the sound of the exhaust tone. Have not seen the issue on any stock ZL1s, but who would keep a ZL1 stock? ; )

Hamadozz · 02-04-2015, 07:00 AM

Quote:

Originally Posted by ZO6 Bryan

The exhaust flaps are open at idle normally. So if you have eliminated the cats it's going to be loud. Combine that with a bigger cam that has earlier exhaust valve open point and it can get pretty loud. It quiets as soon as you drive off and the flaps in the exhaust close, doesn't it?

Yeah it does quiet down once the flaps closes, but what made me question my cat back is that my tuner said that there's something wrong with them and they may need to be replaced. My car is freakin loud and I have a gt9 cam and its a small cam. So I'm thinking about the ADM exhaust valve control or a an aftermarket exhaust system that doesn't sound loud.

Hamadozz · 02-04-2015, 07:05 AM

Quote:

Originally Posted by KaBoom1701

You mod the car for additional HP and then complain about how much louder it is.......ok?

Dude Im trying to find out what's the problem Cuz some guys have the same mods as mine and doesn't sound loud like mine. My car already got impounded Bcuz of sound and I don't want that to happen again.

CAM....ZL1 · 02-04-2015, 07:36 AM

But who would keep a ZL1 stock? ; )[/QUOTE]

"But who would keep a ZL1 stock?"

I love it.

Stephen12ZL1 · 02-04-2015, 07:57 AM

an SS isn't that loud on a dyno and that is what this guy is comparing your ZL1 too. When the ZL1 flaps open at WOT it is very loud in a dyno facility. This is perfectly normal.

Hamadozz · 02-04-2015, 09:30 AM

Quote:

Originally Posted by Stephen12ZL1

an SS isn't that loud on a dyno and that is what this guy is comparing your ZL1 too. When the ZL1 flaps open at WOT it is very loud in a dyno facility. This is perfectly normal.

My car is increadibly loud all the time lol

2013 ZL1 #7860 · 02-04-2015, 09:37 AM

Quote:

Originally Posted by Hamadozz

Dude Im trying to find out what's the problem Cuz some guys have the same mods as mine and doesn't sound loud like mine. My car already got impounded Bcuz of sound and I don't want that to happen again.

Ask your tuner what he thinks is wrong with your exhaust. He has obviously seen and heard it. We haven't...

KaBoom1701 · 02-04-2015, 10:15 AM

Quote:

Originally Posted by 2013 ZL1 #7860

Ask your tuner what he thinks is wrong with your exhaust. He has obviously seen and heard it. We haven't...

+1 This

And you might just want to install a Mild-to-Wild switch.

02-03-2015, 01:04 AM	#1
Hamadozz Drives: 2013 Lingenfelter Packeged ZL1 Join Date: Jan 2015 Location: Qatar, Doha Posts: 8	Trouble with the ZL1 cat backs? hey guys my zl1 have some small modifications that i will list below, and when i tuned it the tuner said the car is really loud and that its not supposed to sound like that. i asked him what could be the problem and he said the cat backs, and keep in mind my cat backs are stock! so did anyone have a problem with their cat backs being louder than normal with time? cuz im beginning to think that the stock cat backs gets disrupted with time! my modifications: Lower cranck pulley gt9 cam tr7 spark plugs dynamics 850 ID injectors stock mainfolds and JBA catless pipes (used to have ARH long tube) supercahrge snout roto fab CAI 93 throttle body heat exchanger water pump car should easily make 570rwhp so share with me what you guys have experienced and what you know!

02-03-2015, 08:54 AM	#3
ZO6 Bryan Drives: 02 Z06, 95 Trans Am, 2012 ZL1 Join Date: Mar 2012 Location: Southeast Posts: 1,838 View My Garage	The exhaust flaps are open at idle normally. So if you have eliminated the cats it's going to be loud. Combine that with a bigger cam that has earlier exhaust valve open point and it can get pretty loud. It quiets as soon as you drive off and the flaps in the exhaust close, doesn't it? __________________ Bryan 2018 ZL1 M6

02-03-2015, 12:54 PM	#6
KaBoom1701 KaBoom1701 Drives: 13' ZL1 Red M6 Join Date: Dec 2012 Location: I.E. SoCal (Yucaipa) Posts: 8,631	You mod the car for additional HP and then complain about how much louder it is.......ok? __________________ Mods: Roto-Fab Intake, WW Res. kit & Big Gulp Air Scoop, Elite Catch Can, ATI Super Damper & 18% OD Pulley, LF Idler pulley bracket, Metco CC breather, ID850 Injectors, Stainless Power Headers w/ ceramic coating, TR71X Spark Plugs, JMS Fuel Pump Booster, Bo White TB, Tuned by Ted @ Jannetty Racing, Ron Davis HX, D3 Reservoir, Pfadt 1" Springs, Moreno Camber Plates, ZL1 Addons Splitter guard washers, Tow Hook kit & rock guards, Hurst Shifter Billet Plus 6 Speed Short Shifter, ZL1 DRL lighting harness, ZL1 Recaro Seats.

02-04-2015, 07:57 AM	#11
Stephen12ZL1 Drives: '21 ZLE A10 Join Date: May 2012 Location: Mechanicsville, VA Posts: 6,824	an SS isn't that loud on a dyno and that is what this guy is comparing your ZL1 too. When the ZL1 flaps open at WOT it is very loud in a dyno facility. This is perfectly normal. __________________ '21 ZLE A10 Wild Cherry PDR 2:00.78 VIR Full 10.68@131.69 1.68 60' '17 ZL1 A10 Mosaic Black PDR/Nav 2:03.08 VIR Full 11.003@129.2 1.75 (sold) '15 Z/28 #325 Black a/c & stereo. 2:10.1 VIR Full (sold) '12 ZL1 A6 Black 10.52@131 1.55 60' 2:13 VIR Full (sold)

02-03-2015, 08:48 AM	#2
unstable vic Account Suspended Drives: 2014 ZL1 Join Date: Jan 2015 Location: Long Island, NY Posts: 342	I've seen on some other threads the inside of the stock mufflers actually coming out of the tailpipe! It looked like steel wool. There replaced under warranty of course.

02-03-2015, 10:20 AM	#4
mrvenicess Drives: 2013 CRT ZL1 auto Join Date: May 2010 Location: Venice Fl Posts: 1,443 View My Garage	I had the same situation but also have long tubes. I added the ADM exhaust valve controller so on start up the exhaust valve stays closed until I open it. Some have said that the packing inside the mufflers fails, mine seems to be starting, although my parts guy was of the opinion that the mufflers are just a series of bent and vented pipes inside. Haven't cut one open so cannot be sure.

02-03-2015, 12:57 PM	#7
NicKey Drives: Nickey Super Camaro Join Date: Nov 2008 Location: Loves Park, Illinois Posts: 1,686	Yes. there are issues with the material in the mufflers not staying in place on modded cars and changing the sound of the exhaust tone. Have not seen the issue on any stock ZL1s, but who would keep a ZL1 stock? ; )

02-04-2015, 07:36 AM	#10
CAM....ZL1 Drives: 2012 ZL1 Join Date: Feb 2012 Location: BENTON, IL. Posts: 1,068 View My Garage	But who would keep a ZL1 stock? ; )[/QUOTE] "But who would keep a ZL1 stock?" I love it.