XtremeVette

OK...just curious....whats the easiest way to get rid of resonance and a low droaning sound....I just got home from my normal 1/2 hour of steady 65+speed on the highway....I love my exhaust sound...but the constant droan when ever I touch the gas I gotta try to quite down lol...

jeff's ears are ringing...lol...and noooooo my music is not gonna go up louder to mask the problem:lol:....Iam trying to get the ringing to stop. :lol:

so any suggestions...please let me know

which do you think caused the low droan sound....

A. Fact that I went to 2.5 inch Stainless steel Y-pipe?
B. Fact that I went without pre-cats this time?

Jeff



[Modified by XtremeVette, 6:24 PM 9/30/2002]

vader86

what catback do you have? its a combination of things

XtremeVette

right now vader I have the Mid America Dynomax Walker 2.25 Rear Y pipe w/crossover tube and the Mid America targa mufflers....

with my original stuff this catback sounded fine to me....there was no resonance.

65Z01

Some people have plugged, either completely or partially, the inner pair of tail pipes with great success in eliminating resonance.

I've noticed some holes that lead from undernieth into the rear storage bin wells. I intend to plug these to see if it helps, though I realy don't mind the sound (of course I haven't driven with the top on in over 3mo :yesnod:).

It would be interesting to feel the mufflers and tail pipes while someone else brings the RPMs up to resonance point/band to try to isolate the cause instead of throwing bandaids at the problem though.

YorkL8apex

I had a local muffler shop install a cross over pipe int he rear Y-pipe. It made a BIG difference in the resonance of my Flowmasters :D

Zip, MidAmerica, etc sell one for about $130 bucks. Local shop did it for $35 :chevy

chucks88

Are your tips sticking out past your bumper by at least a few inches

XtremeVette

chuck was that directed to me?

my exhaust tips sit flush to the bumper.....its an illusion in some of my pics....lol

chucks88

Yes jeff,

Try to bring them out past your bumper-if possible. After I finished installing my TPIS long tubes my exhaust ended up sticking out maybe another 1" to 1 1/2" more than they did before. This actually reduced my droaning to 1900/2000 rpm's only . I was going to suggest the crossover on the rear y but you already have that. That help me out as well.

XtremeVette

ok...chuck thanks for the tip....i will give that a shot too...I got a couple of ideas myself....gonna try it this weekend....I will let ya knw how it goes.

jeff

GusBustamanteJr

Chuck- I am not sure if the tips sticking out past the bumper did it. Resonance will be reduced when installing headers, it happens to all of us. The tips being located further back may be worth a try, we just dont have solid evidence yet.

This is what I do know as fact:

1. Without CATS, there will be huge resonance everytime
2. A crossover on your rear y-pipe may or may not help- did not help me.
3. Blocking one of the outlets from your muffler will eliminate it.

Possible solutions:

1. Install a single, high flow CAT
2. Put the crossover pipe in anyways
3. Get a plumbers fitting and block on of the exits (test with rags to see)
4. I saw the new Cadillacs have a H-Pipe between the two exits on the mufflers........may be worth a try?
5. Weld a stiffener brace between the two exits to reduce vibration
6. Put sound deadening material in the car
7. Wear earplugs
8. Put back stock mufflers or Power Effects and give up!!

XtremeVette

agains lots of more good ideas....


I will thrown in one of my own and let me know what you think:

Gonna try as an experiment to take my original y-pipe and cut off the pre-cats and run with a targa style muffler pipe in there place. Then if that sounds good....gonna try it just with straight pipe in the pre-cats place....see if either of these does anything....

John Row

Put sound deadening material under your carpet.

Threre was a discussion awhile back about some expensive stuff with a brand name and the same stuff cheap with a generic name.

Try searching the archives.

XtremeVette

I actually did find that last night John....though it did not look like it helped that poster out very much...Iam gonna try it anyways....I have the stuff at home just sitting in the shed so why no try it....


anyone know who posted about making his own exhaust plugs that blocked up the inner pipe? I know I saw it here somewhere not too long ago...

jeff

PeteL

I used an exhaust pipe reducer

Fits nicely in my B&B.


Then I tried 4 reducers.

Then I found a metal Sears lawnmower gas cap that covered the small end of the reducer perfectly and riveted it on. Then put a long bolt through the small end so I could get a pair of pliers on it to pull it out. Sorry no pics of the completed plug, my wife lost the charger.

On my car (89) no pre-cats, walker main cat, B&B 3" catback, if I plug one pipe on each side the resonance is all but gone. I can knock a plug loose with a couple WOT runs, as it is just pressure fit. However the rolled end of the B&B tip won't let it escape. For the track I just grap hold of the bolt I put through and work the plugs out.

Working on a new design this winter :lol:

To see if it works on you car just temp plug up two pipes with something, one member used blue pajamas.

Good Luck

BTW, tried all the dynomat (two layers) and all the other stuff. Was a waste of time for me.

gh86E

In a thread about Power Effects resonance, someone emailed me and said his went away when he upgraded to large tube runners. That was the only change he made, and it changed the sound characteristics of the whole engine/exhaust system. Power Effects sound great, but many people end up with an annoying resonance in the 1800-2200 rpm range.

Not everyone however, who had similar setups, had the resonance (of course, it is subjective). So while trying to identify differences, I heard about the intake runner thing.

I'm the one who coated his whole interior with 2-3 layers of sound absorber. That worked very well - I can live with Power Effects during long highway cruises at 1800-2200 rpm.

See my Web site for the cheap alternative I found called B-Quiet (www.b-quiet.com or something like that). Click on the 'and in goes the new...' link on my web site to see how I covered everything with it.


[Modified by gh86E, 1:27 PM 10/1/2002]

TIMSPEED

I have no resonance at ALL with my catback. Dynomax Rear y with crossover and muffler eliminators. I also have the 2½" MAD Front Y-pipe and a R.T. high flow cat...so I dunno...

XtremeVette

yep....your are correct....just like the others have said...

I just went out for lunch and put my hands over the inside tubes to the exhaust....and low and behold the sound definitely changed...when i get home...i will test this out more closely...

but i think we are definitely onto something here....

seems that the resonace is being created by the two pipes baffling each other making a loud droan sound....hmmmm i will post more when i get home...

deaf jeff :cool: :boxing

XtremeVette

well I have been hard at work...thinking up a design to accomodate everything....and I think I got something...on my way home...I will be stopping at home depot and picking up a couple pieces of stainless steel to stamp my prototype diffuser disc out off.....I got a cool idea from SuperTrapp muffler systems...if it works....the xXx2 Diffuser Disc will have been born..lol

I will get pics up and a write up soon as I finish it....
Jeff :cool:


[Modified by XtremeVette, 2:33 PM 10/1/2002]

jimtreber

After getting the front Y without pre-cats and high flow main cat, I was dissappointed in the resonance I ended up with. I went through a lot of trouble making throttle plates in the tailpipes closest to the center of the car (past the mufflers). I used large washers tack welded to a shaft that I could control via low priced electric solenoids. This helped a lot. Then I decided to replace the solenoids with common vacuum pull-offs so the throttles would open only under load and automatically close during cruise. I wasn't sure if I could run a vacuum line this long but it worked. After all this I found that extending the exhaust a few inches so it was at least passed the bumper accomplished more than all the messing around I did with my makeshift power effects system.

LT4BUD

Looks like the pieces (reducer) B&B sent me to install. They sent 4, one for each outlet. Never installed them for several reasons, most significant was how to secure them in place. Weld???