Loud Cabin Engine Drone Noise
Thread Starter
4th Gear
Joined: Feb 2018
Posts: 4
Likes: 0
From: Lawrenceburg Indiana
Loud Cabin Engine Drone Noise
I recently purchased a 96 LT 1 Coupe (my first Corvette) and the cabin engine drone noise is severe when the engine is under any type of load such as accelerating from a start and going through several gears or pulling even a small grade. The drone tone level is perfect only when cruising. It sounds great outside but not inside! The car is like new and the entire exhaust system is solid, all welds are complete, no rust, etc. Insulation kits? Catback? Muffler deletes? Different mufflers? I am very confused and need the correct fix - the first time. Thanks.
Thread Starter
4th Gear
Joined: Feb 2018
Posts: 4
Likes: 0
From: Lawrenceburg Indiana
Using a flashlight and a mirror (and reading upside down and backwards) I finally located information on the top of a muffler. "Flowmastek" and the numbers 100816 appear on the mounting bracket welded to the muffler. I went to Flowmaster's website and entered the 6 digit number with "no results found". The exhaust system may be operating exactly as designed but I can not imagine anyone tolerating that extreme in-cabin drone noise. I noticed that Corvette Central has a muffler made for the c4 LT 1 that specifically lowers the drone noise. Has anyone purchased and installed them and if yes, what is the satisfaction level for sound both inside and outside? I greatly appreciate any recommendations.
Last edited by gibsonJ200; Feb 14, 2018 at 10:16 PM.
Instructor
Joined: Oct 2017
Posts: 199
Likes: 24
From: Palmetto FL
I recently purchased a 96 LT 1 Coupe (my first Corvette) and the cabin engine drone noise is severe when the engine is under any type of load such as accelerating from a start and going through several gears or pulling even a small grade. The drone tone level is perfect only when cruising. It sounds great outside but not inside! The car is like new and the entire exhaust system is solid, all welds are complete, no rust, etc. Insulation kits? Catback? Muffler deletes? Different mufflers? I am very confused and need the correct fix - the first time. Thanks.
Racer
Joined: Jul 2017
Posts: 422
Likes: 53
From: PA
I recently purchased a 96 LT 1 Coupe (my first Corvette) and the cabin engine drone noise is severe when the engine is under any type of load such as accelerating from a start and going through several gears or pulling even a small grade. The drone tone level is perfect only when cruising. It sounds great outside but not inside! The car is like new and the entire exhaust system is solid, all welds are complete, no rust, etc. Insulation kits? Catback? Muffler deletes? Different mufflers? I am very confused and need the correct fix - the first time. Thanks.
I got the flowcrapper system on my 96 also, drone is bad. Bought the car that way, never would have put that system on. Not just one RPM range either, like some other systems. Drone starts around 1200-1400, goes away, then it's back around 1800-2100. I've never owned a vette before with a flowcrapper system but had one on a 92 chevy P/U, the drone was horrible on that truck too. Pulled it off & bought magnaflow, less drone but still some.
Race Director
Joined: Feb 2002
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From: Compound in the Grove, Ga.
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First Welcome & grats on your 96. Put them on my 95 LT1 bad drone went back to stock, Autos are worse about it than manual as you can not down shift to get out of the drone RPM.
Last edited by FASTAZU; Feb 15, 2018 at 09:18 AM.
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Thread Starter
4th Gear
Joined: Feb 2018
Posts: 4
Likes: 0
From: Lawrenceburg Indiana
Many thanks to everyone! No doubt deciding on a replacement exhaust system will be my next step including checking out Corsa. I continue to enjoy my 97 Harley FLSTS Heritage Springer Softail, Infiniti Sport Coupe and 70 Chevelle but I have to say I wish I had been bitten by the Corvette bug sooner. I am now impassioned with another Man Toy and completely out of garage space. Fortunately my beautiful wife shares the same enjoyment.
Racer
Joined: Jul 2017
Posts: 422
Likes: 53
From: PA
Many thanks to everyone! No doubt deciding on a replacement exhaust system will be my next step including checking out Corsa. I continue to enjoy my 97 Harley FLSTS Heritage Springer Softail, Infiniti Sport Coupe and 70 Chevelle but I have to say I wish I had been bitten by the Corvette bug sooner. I am now impassioned with another Man Toy and completely out of garage space. Fortunately my beautiful wife shares the same enjoyment.
Racer
Joined: Feb 2015
Posts: 279
Likes: 9
From: ridgecrest ca
how far do your exhaust tips stick out past the rear valance? if they don't go past the valance far enough you will get a ton of drone inside the car .I had your problem on my 90 zr1 extended the tips out 2 inches and problem was solved
Pro
Joined: Jan 2003
Posts: 706
Likes: 47
From: Denver Colorado
This exhaust extension is likely the best and least expensive answer to your drone issue. The C4 is very sensitive to the noise getting into the rear fascia area and it is simple to add some length to the exhausts and get them in back of the fascia. The first C4s, the 1984s, had turn downs instead of straight pipes and didn't have the drone issues to the same extent. That said, I had Flowmasters on my '84 and they were OK in stock form. Of course I had spent a lot of time around jets.
Thread Starter
4th Gear
Joined: Feb 2018
Posts: 4
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From: Lawrenceburg Indiana
Thanks again to everyone for your assistance and I will update this thread when the tips have been extended - hopefully very soon!
Bob
Safety Car
Joined: May 2001
Posts: 4,759
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From: Fairfax Virginia
I have a 1988 C4 and it was time to replace the exhaust so I bought a Chambered Exhaust System from Allen's Stainless Exhaust. I bought the standard version (aluminized Steel) not the Stainless version.
The Chambered pipes sound like side-pipes but the noise comes out the rear of the car. The whole system was a cat back system and it was easy to install. I installed a hi-flow Catalytic converter at the same time and it has worked for over 15 years and going strong.
Even with the Catalytic converter it was less expensive than some of the higher end aftermarket "Performance" exhaust systems. Another benefit is that you get rid of the existing heavy mufflers when using a Chambered Exhaust system.
The sound is "awesome" (behind the car) and the stereo works great.
Good luck trying to deal with existing drone, Look at the bright side, it is only temporary!
The Chambered pipes sound like side-pipes but the noise comes out the rear of the car. The whole system was a cat back system and it was easy to install. I installed a hi-flow Catalytic converter at the same time and it has worked for over 15 years and going strong.
Even with the Catalytic converter it was less expensive than some of the higher end aftermarket "Performance" exhaust systems. Another benefit is that you get rid of the existing heavy mufflers when using a Chambered Exhaust system.
The sound is "awesome" (behind the car) and the stereo works great.
Good luck trying to deal with existing drone, Look at the bright side, it is only temporary!
Drifting
Joined: Sep 2009
Posts: 1,765
Likes: 1,507
From: Willis, tx
I recently purchased a 96 LT 1 Coupe (my first Corvette) and the cabin engine drone noise is severe when the engine is under any type of load such as accelerating from a start and going through several gears or pulling even a small grade. The drone tone level is perfect only when cruising. It sounds great outside but not inside! The car is like new and the entire exhaust system is solid, all welds are complete, no rust, etc. Insulation kits? Catback? Muffler deletes? Different mufflers? I am very confused and need the correct fix - the first time. Thanks.
Last edited by polo91; Feb 18, 2018 at 10:35 PM.
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 165
From: Nashville TN
2017 C4 of Year Finalist
Had the same mufflers on my '85. Loved how it sounded when you revved it but the drone was unbearable. Went back to stock which isn't nearly so nice when you put your foot down, but makes longer drives bearable.
Something that helps with road noise overall is this stuff called Frost King insulation. You can buy it at Lowe's, it's designed for A/C insulation. It's like this rubber stuff with aluminum backing and self-adhesive. Take your carpets and door panels out and put a layer or two of the stuff down in there, then put it all back together. Makes a huge difference in road noise-but be warned that you will add a little weight. It's not terrible but it would definitely make a difference on a drag strip.
Something that helps with road noise overall is this stuff called Frost King insulation. You can buy it at Lowe's, it's designed for A/C insulation. It's like this rubber stuff with aluminum backing and self-adhesive. Take your carpets and door panels out and put a layer or two of the stuff down in there, then put it all back together. Makes a huge difference in road noise-but be warned that you will add a little weight. It's not terrible but it would definitely make a difference on a drag strip.
Drifting
Joined: Feb 2008
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From: NE Ohio
2024 C4 of the Year Finalist - Unmodified