Shhhh!! Louder ain't always better

[rpounds]

Hi guys and gals. My '75 is equipped with the stock 2 into 1 into 2 exhaust with straight through cat and Flowmaster 40's. The car sounds nice, however there is a harmonic in the exhaust at certain RPM's. This harmonic is in between about 1500 and 1800, just about where the engine runs when going for a nice cruise around town or down by the beach. Of course this goes away at higher engine speeds such as encountered on the freeway. Although it sounds nice, it does get annoying after a while, especially when cruising with the little lady. It's difficult to carry on a conversation and makes the radio next to worthless.

Okay, so here's my question. What kind of mufflers is everyone running? I would like to ensure decent flow, but I really need to reduce the noise level or at least get rid of the harmonic. Any suggestions?

Thanks, Ron

 

[Chas]

i have headers and flowmasters on my 73.....i had this type of problem , until i put in reflectix and carpet pad....under the carpet i used the stuff from home depot...then i have access to a thin carpet type mat...its recycled clothing meshed into a thin layer about 3/16 thick....i actually did this for heat , but heat finds a way in eventually...but the sound diffrence was amazingly better...could actually talk to passenger and listen to the radio at the same time....car sounds great...now so does my stereo and passenger!
hope it helps...
Chas

Hi guys and gals. My '75 is equipped with the stock 2 into 1 into 2 exhaust with straight through cat and Flowmaster 40's. The car sounds nice, however there is a harmonic in the exhaust at certain RPM's. This harmonic is in between about 1500 and 1800, just about where the engine runs when going for a nice cruise around town or down by the beach. Of course this goes away at higher engine speeds such as encountered on the freeway. Although it sounds nice, it does get annoying after a while, especially when cruising with the little lady. It's difficult to carry on a conversation and makes the radio next to worthless.

Okay, so here's my question. What kind of mufflers is everyone running? I would like to ensure decent flow, but I really need to reduce the noise level or at least get rid of the harmonic. Any suggestions?

Thanks, Ron

 

[Macgyver]

Ive got the same deal so I bought a seriously loud radio. Theres some stuff called dynomat that is more expensive then what Vettedude73 mentioned and is what high dollar installation places use like custom sounds to reduce road noise. I used it in my Accord for the doors and trunk door and its quite amazing. But the problem is is that the whole rear area is almost hollow, meaning below the carpet, which if you slap that area w/ your hand youll see what I mean. At least for my year. I think i narrowed it down to one major source though. its the weather stripping for the rear glass that will allow the whole thing to vibrate slightly against the whole frame.

At that rpm level w/ true duals, no cats, and flow40's, youll probably loose your mind and so will the misses so Im no help there. My main squeeze actually thinks its tough. I drive it daily to work (used to rather ) so its a thing of the past for me.:cool

 

[johnd]

I have dynomax...just put them on like two days ago and I have been all through the RMP band with them ...anyway they sound awesome...and they are not overly annoying...the cam is heard more then the exhaust at idle and I crusie alot including like two hours tonight and it sounded good and not annoyingly loud either...just my .02

John Dykstra

 

[Fishman]

Ron... I had the same issue with my Flowmasters. Put in a true dual exhaust... it was still pretty much the same. The BIG difference came when I put in the headers... the car actually ran noticeably quieter. The stock manifolds created a bit of vacuum at the heads and lots of resonance... the headers moved the vacuum away from the heads. At least that is what I was told by an 'expert'. I am not a vacuum scientist.

 

[johnd]

I also have long tube headers that go into true dual exhaust...so that may make some difference...

 

[Brack]

I just put The 40 series on mine last week........But I put the Delta Flow series 40.....same sound @ idle and WOT......but has less resonance and doesnt create the deep interior hum in the 1400-2000 rpm range

 

[Ludigdrums]

I have Dynomax Ultra Flo's true dual, no cats, and a H crossover pipe...they sound great!!! The only time they scream is at WOT and heavy throttle, otherwise, the sound is very minimum! I like em!

- Jeremy

 

[brusso]

. Although it sounds nice, it does get annoying after a while, especially when cruising with the little lady. It's difficult to carry on a conversation and makes the radio next to worthless.

Thats just what I need. Can't get those 40's on soon enough!:argue

 

[Macgyver]

I love it! Im right there w/ ya. I wish my couch had some side pipes sometimes. Sheesh.


Anyone ever try these Targa mufflers. Man they look loud.
http://www.ecklers.com/product.asp?dept%5Fid=1328&pf%5Fid=A4239&mscssid=A0S3P01DK8PQ9GBV56P5XCSL8QNK1LN5

 

[Bob_K]

Anyone ever try these Targa mufflers. Man they look loud.
http://www.ecklers.com/product.asp?dept%5Fid=1328&pf%5Fid=A4239&mscssid=A0S3P01DK8PQ9GBV56P5XCSL8QNK1LN5

Mid America has the same ones (or very similar) for less. I was thinking about putting them on my '79 and am also interested in knowing what they sound like.

 

[rpounds]

Thanks guys. Maybe I'm getting old, but I just can't handle the constant noise anymore. My Flowmasters have a straight chrome tip coming out of them, so I'm thinking about trying to find some sort of baffle that can be put in place to keep it quiet when I wish but can be 'uncorked' at other times. If I can't find anything, I may be able to design something.

 

[brusso]

Well I got the "40's" on today. I'm in heaven. One of my Harley owning friends said "damn that's loud!" These guys here did the job. www.louscustomexhaust.com

I'll have to get some pics and post-em. The tips they used are kind of differrent, for a 75. They kind of look like the tips used on the older ones. The openning is rectangular in shape.

 

[Macgyver]

Enjoy! Man I still get real excited when I start her up since I park in the garage. Then I look around and no ones there to share that excitement.
Nice and loud w/ a great deep rumble. Love those 40's. Give it 3-4 months and you might be like me and be wanting louder. like some sidepipes

 

[brusso]

Enjoy! Man I still get real excited when I start her up since I park in the garage. Then I look around and no ones there to share that excitement.
Nice and loud w/ a great deep rumble. Love those 40's. Give it 3-4 months and you might be like me and be wanting louder. like some sidepipes

UHMMMMMMMMMM............sidepipes;worship

 

[atmmac]

I have dynomax...just put them on like two days ago and I have been all through the RMP band with them ...anyway they sound awesome...and they are not overly annoying...the cam is heard more then the exhaust at idle and I crusie alot including like two hours tonight and it sounded good and not annoyingly loud either...just my .02

John Dykstra

I have the Dynomax on my impala and i agree!

-Andy