I have a 79 cutlass 455 engine built with cam etc
i currently have dynomax mufflers and they sound good at idle but I find when cruising they drone you out
any suggestions on a quieter performance muffler ?
or Is adding in resonators a good option ?

 

Which Dynomax muffler are you using and where does the exhaust exit from under the car? I have the 2.5" Super Turbo's with tail pipes on my car and no drone.

 

The Dynomax are some of the quietest available. You're going to need resonators or sell the car in favor of something more quiet, like a funeral car.

 

I have the Dynomax Super Turbo mufflers on my 67 Chevelle and love them. No drone. They are 3" in/out and exit right before the rear axle---no tail pipes. I get compliments on how they sound with my 6oo+ HP BBC all the time.

 

Are you running a true dual system, or an 83/84 H/O style Cat Back Dual Exhaust system?

 

Question, how are the Dynomax compared to the Walker Quiet-Flow mufflers in loudness?

 

On my BBC with 3" exhaust they are loud when you get over 3K RPM but I wanted something that sounded better than the quiet ones. I would guess they are likely much louder than the quiet flows but they sound sooooo good!

 

I will have to see if the PO has paper work on them not sure what they are

 

yes true dual exhaust pipes exits behind rear wheels

 

A crossover pipe just past the trans will mellow the sound. Frankly I've never had a drone problem with Dynomax super turbos. Which Dynomax mufflers do you have?

 

Joe has a good point on the crossover pipes whether you use the X or H style. I am not a proponent of either, so I don't use them---FYI.....

On my 442 resto, I used the Pipes Race Pro mufflers 3" in and 2.5" out with tail pipes. That is a much tamer sound than my Dynamax Super Turbos on the Chevelle but to be honest--I still prefer the Dynomax sounds. There is no drone on the Pipes mufflers either.

 

im not sure I’ll have to check paper work
I did read that the super turbos are quite
but I don’t think I have the super turbo

 

I would not call them quiet, but I guess noise is relative depending on what you are comparing them to.

 

anyone put in resonators with mufflers ?
bad idea ? What you think

 

Again we do not know what to think until we know whats on there now. Take some pictures of them and post them.

 

I have straight pipes and flowmasters on one, and a Gardner exhaust on another. I prefer the Gardner.

 

found the receipt from 1997
Dynoflow 17734 looks like a super turbo but they are old.

 

A lot of us use that same muffler without issue. My guess is that the innards have deteriorated.

 

yes probably seen its fair share of abuse in the last 25 years

 

im also thinking that materials and technology have changed over 27 years

 

Helmholtz-resonator-style noise reduction pipe may help. Requires a bit more work. Just depends if you have the room. Looks strange, but it works. I know several 5/6th gen Camaro guys using these with different catback systems, although some just use a J-pipe instead of the proper chamber. Just something to consider.

If seriously interested in tackling drone, here's a nice little blog entry where someone built an exhaust system and used his own spreadsheets and caculations to build an H.R. to reduce/eliminate the drone. Includes links to get a copy of his Excel calculators if you want to build your own.

Drone Reduction - Wilhelm Raceworks, LLC

 

I have 20" DynoMax Super-turbo mufflers PN#17749 on my '72 convertible and the exhaust was way too loud. I like the sound of these mufflers but something had to be done about the loudness. My solution was to install resonators in the tail pipes, between the rear wheels and the bumper cutouts. The resonators allowed the throaty, rumble that I liked but quieted things down to an acceptable level (which is still kinda loud). Here's a pic and a link to my build thread.

https://classicoldsmobile.com/forums...1/#post1573528

Rodney

 

weird. From all I read these are suppose to be quiter than most

 

My car has a set of Sonic Turbo mufflers that I installed in the early 80s and they still sound good. They have been "abused" through a couple of engine, transmission, and rearend iterations but are still holding up well.

 

I'm surprised by the too loud comments with Dynomax Superturbo's. Other than on my Dakota, which until the tail pipe broke the back joint due to the weight of the tip, it wasn't too loud. Sounded almost stock inside till you rolled down the windows. My 70 was too quiet with them. I think resonators are the way to go, anything but stock style mufflers will be louder.

 

I was surprised that my exhaust was so loud; I bought the 20" SuperTurbos just to be on the safe side and it was still too loud. This is my first high performance build so I didn't really know what to expect. The engine has 10.25:1 compression, cam specs are 233@.050; .557" lift, 1-5/8 Hooker headers, 2-1/2" dual exhaust, no crossover pipe. The resonators made a big difference without neutering the sound.

Rodney

 

Thank you. Maybe I will try this

did you find the drone went away ?

 

I never had much of a drone problem, just really loud when I stepped on the gas. The resonators cut the full throttle loudness by 50%.

Rodney

 

I ended up installing 2 vibrant resonators 1141

it takes the drone right out