More Exhaust stuff- Cats
Thread Starter
Melting Slicks
Joined: Feb 2005
Posts: 3,204
Likes: 4
From: Midland Georgia
St. Jude Donor '06
More Exhaust stuff- Cats
My engine is nearing completion and we will get around to the install in a few weeks. I am going back with headers (Had them Jet hot coated). From the Headers back is a decision I have to make. I currently have an older 3" B&B Triflow exhaust sitting at the shop. I have no catalytic converters. This exhaust is really to loud and all the typical resonance at highway cruising speed in 6th gear. The car is to loud to speak to another person in the cabin at highway sppeds. Time to quiet this monster down. Yes, I am married.
Questions.
1.) If I add Cats to this set up will it cut my resonance? I would think that it would lower the decibels blowing through my exhaust but I am not sure about resonance. The resonance is literally ear stinging.
2.) A local exhaust shop has told me they can custom build a system that would include cats and dynaflow mufflers for around $700. How are the dynaflows.
Car is modded as follows: 94 coupe, 6 speed, LT4 hotcam, crane roller rockers, Hooker long tube headers, SLP intake with three K&N filters..
Opinions and solid advice on your set ups. Yes, I ask some of these questions in the past, however, that was months and months back. It is now time to spend money. So I need input.
Questions.
1.) If I add Cats to this set up will it cut my resonance? I would think that it would lower the decibels blowing through my exhaust but I am not sure about resonance. The resonance is literally ear stinging.
2.) A local exhaust shop has told me they can custom build a system that would include cats and dynaflow mufflers for around $700. How are the dynaflows.
Car is modded as follows: 94 coupe, 6 speed, LT4 hotcam, crane roller rockers, Hooker long tube headers, SLP intake with three K&N filters..
Opinions and solid advice on your set ups. Yes, I ask some of these questions in the past, however, that was months and months back. It is now time to spend money. So I need input.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
With your mods I would expect you are developing over 350chp. This means you need 800cfm of exhaust flow, or 400cfm per side.
Check out the intended cats & mufflers for flow specs to assure they won't cost any HP.
BTW, I know a guy who has Corsas on his GS and loves the sound. They sound deep at idle and he says they are quiet enough while cruzin' but roar at WOT.
Check out the intended cats & mufflers for flow specs to assure they won't cost any HP.
BTW, I know a guy who has Corsas on his GS and loves the sound. They sound deep at idle and he says they are quiet enough while cruzin' but roar at WOT.
Safety Car
Joined: Sep 2003
Posts: 3,692
Likes: 5
From: Hayward CA
Cats will lower the decibel level, but they will NOT cut the resonance. IMHO, there is only one cure for the resonance - Corsa.
If it were me, I'd add some gears - 4.10's. They keep your rpms up and out of the "drone-zone" so the resonance is not as bothersome.
If it were me, I'd add some gears - 4.10's. They keep your rpms up and out of the "drone-zone" so the resonance is not as bothersome.
Thread Starter
Melting Slicks
Joined: Feb 2005
Posts: 3,204
Likes: 4
From: Midland Georgia
St. Jude Donor '06
350+ I hope so
With your mods I would expect you are developing over 350chp. This means you need 800cfm of exhaust flow, or 400cfm per side.
Check out the intended cats & mufflers for flow specs to assure they won't cost any HP.
BTW, I know a guy who has Corsas on his GS and loves the sound. They sound deep at idle and he says they are quiet enough while cruzin' but roar at WOT.
Check out the intended cats & mufflers for flow specs to assure they won't cost any HP.
BTW, I know a guy who has Corsas on his GS and loves the sound. They sound deep at idle and he says they are quiet enough while cruzin' but roar at WOT.
I like stealth
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Cats would reduce the noise level, and possibly change the resonant RPM a bit, but kill it? no they wont kill it.
There are several things to do to cut the resonance, but there is no way to eliminate it without going to something like Corsa. Crossover pipes, a resonator, extending the tips past the bumper more, or just plugging up a pipe with steel wool have been tried and help reduce it.
There are several things to do to cut the resonance, but there is no way to eliminate it without going to something like Corsa. Crossover pipes, a resonator, extending the tips past the bumper more, or just plugging up a pipe with steel wool have been tried and help reduce it.
Racer
Joined: Feb 2006
Posts: 269
Likes: 0
From: Vancouver B.C.
Jakers,
My vette came with cheap turbo mufflers when I first got it.....the resonance was awful. Couldn't talk at 1600-2000rpm. I know exactly what you're talking about. If I wanted my wife to continue riding with me I knew I had to change it! (Actually, the REAL reason is I didn't want to blow my speakers
)
I put on Dynamax mufflers and the resonance dropped by at least 90% (100% being none at all). I like these mufflers, as they sound like equals to the renouned Corsa system. (rumble at idle/throaty at mid and no resonance/wild at wot)
My exhaust set-up is: Stock manifolds, two cats, no crossover, true dual. I have a cam and at idle you hear it well.
My vette came with cheap turbo mufflers when I first got it.....the resonance was awful. Couldn't talk at 1600-2000rpm. I know exactly what you're talking about. If I wanted my wife to continue riding with me I knew I had to change it! (Actually, the REAL reason is I didn't want to blow my speakers
)I put on Dynamax mufflers and the resonance dropped by at least 90% (100% being none at all). I like these mufflers, as they sound like equals to the renouned Corsa system. (rumble at idle/throaty at mid and no resonance/wild at wot)
My exhaust set-up is: Stock manifolds, two cats, no crossover, true dual. I have a cam and at idle you hear it well.
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Racer
Joined: Feb 2006
Posts: 269
Likes: 0
From: Vancouver B.C.
I was considering the hp gain in adding an X pipe myself. I've wondered if it would increase the resonance of my system? Thinking it wouldn't....because of the mufflers I use (Dynamax)???
Your thoughts?
Race Director
Joined: Aug 2003
Posts: 11,043
Likes: 3
From: San Jose Pat Tillman - American Hero
I'm sure he'll agree if he sees this post!
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
I removed the stock convertors on my '92 today; the rest of the system is stock. It sounds much better now with a noticable increase in torque. There was no resonance increase; just a better sounding system.
Bernie
Bernie
Race Director
Joined: Jan 2002
Posts: 12,263
Likes: 86
From: O'Fallon Missouri
I would have to see track times or dyno sheets to believe that claim.
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
It doesn't take a dyno sheet for me to be able to feel the difference after removing the convertors. They were the original ones and removed them because I felt they were clogging after all these years. The car responds better than it did and the exhaust note is now a nice rumble instead of a whisper! Your "BS" is my reality!
Bernie
Bernie
Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
Quick question, where do you all go to have your cats removed and a straight pipe installed in their place? Will an exhaust shop do this in spite of the legal issues of going catless?
Also how much does this cost? I need to have this done right away because my passenger side cat is completely stopped up, and rather than put new ones on I was going to just drop the extra weight.
Also how much does this cost? I need to have this done right away because my passenger side cat is completely stopped up, and rather than put new ones on I was going to just drop the extra weight.
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
It is my understanding that if you cut the cats off and drive the car to a muffler shop they will install the pipes for you but they will not remove the cats and do it. I have friends that race and have the equipment to do this. I paid them $75.00 for their effort.
Bernie
Bernie