Any tricks to reducing resonance? (vette)
07-01-2004, 05:51 PM
#1
Any tricks to reducing resonance? (vette) Anyone know any old tricks? I put dual cutouts on my vette today. The car has longtubes (1 3/4) into 3" highflow cats, 3" dynomax bullets, x-pipe, then 2 3" cutouts with turndowns bolted on. The car has an incredible resonance from about 1750-2250 though. It's so much it just sounds like a really loud hum. Over that is fine, so is under that.
The weird part is that I had this same setup on my old camaro, FLP longtubes, high flow cats + y-pipe, dynomax bullet, then single 3" cutout. It was kinda bad with the windows up (I'd close the cutout if it was raining), but with the windows down there was really no resonance. With the vette, it gets better with the windows up (almost unnoticable). Kinda strange.
I didn't have a turndown on the camaro, it was just pointed at the rear axle. I put turndowns to prevent from pointing the exhaust at the rear of the vette. They basically point to the ground. I wonder if that might be it? Sounce bounces off the pavement, and since the car is so low it causes a resonance?
Anyway, any tricks? I've had suggestions of taking off the turndowns (which I'm about to do), to pointing the turndowns at each other (not sure how that would work).
It sounds incredible except for that range, the whole exhaust note just turns into mush. What's also weird is that it seems to sound fine outside the car, but inside the car with the windows DOWN it sounds very bad.
Dope
The weird part is that I had this same setup on my old camaro, FLP longtubes, high flow cats + y-pipe, dynomax bullet, then single 3" cutout. It was kinda bad with the windows up (I'd close the cutout if it was raining), but with the windows down there was really no resonance. With the vette, it gets better with the windows up (almost unnoticable). Kinda strange.
I didn't have a turndown on the camaro, it was just pointed at the rear axle. I put turndowns to prevent from pointing the exhaust at the rear of the vette. They basically point to the ground. I wonder if that might be it? Sounce bounces off the pavement, and since the car is so low it causes a resonance?
Anyway, any tricks? I've had suggestions of taking off the turndowns (which I'm about to do), to pointing the turndowns at each other (not sure how that would work).
It sounds incredible except for that range, the whole exhaust note just turns into mush. What's also weird is that it seems to sound fine outside the car, but inside the car with the windows DOWN it sounds very bad.
Dope
07-02-2004, 07:21 PM
#3
Small update:
I got some turndowns fabricated that I can turn any way I want.
I've tried:
Straight down
Pointing right at each other
Pointing straight out the sides of the car
No turndowns at all (just open cutout)
The only difference I felt at any point was pointing them out the side. Maybe 10% reduction in sound.
So anyway, I put the caps on just to see if the resonance was gone. It is. Completely. The car is as quiet as a stock 4thgen. No rattle, not even a hint of resonance, even at 20mph in 5th gear.
So I guess it's just the cutout location then. Next up is those collector inserts, maybe about 20 of them in random locations in the pipes. I can't be driving this car with the cutouts capped, it sounds way too civilized. Maybe as loud as a stock Z06 at best. BAH!
Think I'm gonna go to Home Depot, get some duct insulation and line the tunnel cover with it.
And then torch the car.
Dope
I got some turndowns fabricated that I can turn any way I want.
I've tried:
Straight down
Pointing right at each other
Pointing straight out the sides of the car
No turndowns at all (just open cutout)
The only difference I felt at any point was pointing them out the side. Maybe 10% reduction in sound.
So anyway, I put the caps on just to see if the resonance was gone. It is. Completely. The car is as quiet as a stock 4thgen. No rattle, not even a hint of resonance, even at 20mph in 5th gear.
So I guess it's just the cutout location then. Next up is those collector inserts, maybe about 20 of them in random locations in the pipes. I can't be driving this car with the cutouts capped, it sounds way too civilized. Maybe as loud as a stock Z06 at best. BAH!
Think I'm gonna go to Home Depot, get some duct insulation and line the tunnel cover with it.
And then torch the car.
Dope
