Exaust resonance
Thread Starter
Instructor
Joined: Nov 1999
Posts: 155
Likes: 0
From: Eureka NV
Exaust resonance
During a moment of sheer brilliance (us old guys have them quite often, the Dr. calls it alzheimers) I gutted the catalytic converter on my 84 while performing considerable engine modification. When I got back on the road I learned that the exhaust resonance between 1300 and 1700 rpm is almost intolerable! It is worst right in the middle of that range. (1500 rpm) I am wondering if any of you have come up with a fix short of replacing the whole damned exhaust system. I am not totally objectionable to putting a cat back on it if that is what it takes…. I have considered a couple of things myself ie. Replacing the old gutted cat with 2 pieces of pipe making it a true dual exhaust. I have also seen a replacement pipe that has a balance pipe between the pipes going from the cat to the mufflers but have no idea if that is effective. I am sure some of you out there have tackled the resonance problem with some measure of success. Any info you can offer will be appreciated!
Ken
Ken
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Exaust resonance (KJones)
My FlowMaster cat-back has resonance there too.
I've heard of two possible solutions here on the Forum:
1) cut and weld in a crossover pipe between the two legs of the Y
2) put a reducer in each inside exhaust pipe tip.
I've heard of two possible solutions here on the Forum:
1) cut and weld in a crossover pipe between the two legs of the Y
2) put a reducer in each inside exhaust pipe tip.
Safety Car
Joined: Nov 1999
Posts: 4,289
Likes: 1,162
From: Green and Wet Western Oregon
2023 C7 of the Year Winner - Unmodified
2018 C6 of Year Winner
Re: Exaust resonance (KJones)
The only way I found to completely eliminate the resonance was to install a Corsa cat-back system. Since you have gutted the cat, I don't know if the Corsa's would help you that much?!?
Team Owner
Joined: Nov 1999
Posts: 32,782
Likes: 11
From: Former NCM Drag Racing coordinator, National director Corvette Challenge Spring Hill, Tennessee: Whiting, New Jersey
Cruise-In VI Veteran
Cruise-In VII Veteran
Re: Exaust resonance (KJones)
Turn the RADIO up!! It will go away :blueangel:
Safety Car
Joined: Jul 2001
Posts: 3,615
Likes: 1
From: New Lenox IL
Re: Exaust resonance (KJones)
I have a Corsa catback system and never gutted my cats and I get the same thing. Its so bad, that it actually sounds like a rattle. I'm gonna put it up on the lift later this week to see if anything is loose but I doubt it. Should I even be getting this? Its the worst once the car has heated up.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Instructor
Joined: Nov 1999
Posts: 155
Likes: 0
From: Eureka NV
Re: Exaust resonance (65Z01)
First off I would like to thank everyone for their responses to my post on exhaust resonance!
I was particularly interested in the simple fix submitted by 65Z01 in reference to restricting the inboard exhaust tips. I installed plugs in both tips and VOILA..... The resonance is GONE..... Now comes the question, what about economy and performance! I immediately drove to Vegas and back (675 mi. round trip) and got my normal 24-mpg with no apparent diminution in performance.
This makes me willing to try the following:
Replace both mufflers and their attendant dual outlets with a single outlet, low restriction unit.
Add something like an LT1 tip for looks.
Thanks again to everyone for their suggestions… especially the ones on earplugs and turning the radio up!! Lol
Take care and be safe,
Ken
I was particularly interested in the simple fix submitted by 65Z01 in reference to restricting the inboard exhaust tips. I installed plugs in both tips and VOILA..... The resonance is GONE..... Now comes the question, what about economy and performance! I immediately drove to Vegas and back (675 mi. round trip) and got my normal 24-mpg with no apparent diminution in performance.
This makes me willing to try the following:
Replace both mufflers and their attendant dual outlets with a single outlet, low restriction unit.
Add something like an LT1 tip for looks.
Thanks again to everyone for their suggestions… especially the ones on earplugs and turning the radio up!! Lol
Take care and be safe,
Ken