MY99TAWS6

iTrader: (3)

I have as you can see from my sig an 408 with a pretty mellow no lope cam.
I have the aps twin kit and have no cats. I am running hooker ypipe to currently hooker aerochamber catback. I had a b and b catback but got a bit bored and just put the hooker on after liking the way it sounded on buddies lt1 with mac mids and high flo cat.

I wanted something pretty quiet as have cutout to use when want it loud.

So here is the deal my b and b and my hooker catback seem pretty darn loud to me. Now this might be weird but it seems to be louder at night?

I am a bit baffled. I thought my turbos would really quiet down the sound. I have stock type exhaust manifolds with the aps kit. So why is it so loud. Not talking idle but mostly just talking driving around. I can maybe go to fourth gear in town still have m6 currently and not sure how much louder it will be with auto swap. I don't really care how loud it gets wot but it just seems a bit too loud for me. Maybe am getting old or something.

So curious what the deal is. Is my 408 louder than a 346? Do my big afr 225 heads somehow make it louder? And how come the turbos don't quiet it down.
I guess could put high flow cats on but to me cats are THE DEVIL, maybe a spiral bullet in the i pipe if there is room for it and cutout.That might be the best of both worlds. And can always open cutout various amounts.Maybe I should go to stock exhaust and cutout.

Oh and do cars get louder when richer or leaner? When its hotter or colder outside?
And one last question.I had a big misfiring problem for awhile but its finally fixed. Could this have blown anything out of the hooker aerochamber and caused it to get louder.

95lsxss

I cant answer most of your questions but i will say aerochambers are just plain LOUD!!! I had them on my 95 impala ss, stock pipes with 3" aerochambers, and it sounded like i had a big block under the hood

elias_799

iTrader: (8)

just throw in some high flow cats, they are no good anyway to pass emission, but will quiet the car down a little bit. also i know what you mean about the car being louder at night, i used to have a gtp and it was always louder on a nice cold night and ran slightly stronger. i think it all comes down to the air being cooler at night then daytime, which means you can burn more fuel and make more power. and that might increase the noise the motor makes.

ta02zx10r

iTrader: (19)

I'm not sure what horsepower you are making but that plays a big part of how a car sounds. It takes x amount of fuel/air to achieve a horsepower level (with some variances such as pulleys and other mods to free up horsepower). Nonetheless in regards to just the engine itself it does have to burn the fuel mixed with air. Once you start making more hp you are actually making a bigger explosion in the cylinder to achieve that hp. That is in turn going to make the car louder. As far as the sound difference in night vs. daytime I have no idea. I have noticed that when my car is cold (cold start) it is a lot louder until it warms up. I don't know if this involves the exhaust being cold or the engine being cold and not being affected by any heat soak which allows a denser air/fuel mix. I might be way off on all of this but this is how I percieve it. If someone has any other theory please step in.

SincalT/A

iTrader: (16)

What you hear from a internal combustion engine is the valves+pressure+air being forced out by the piston.You would only hear the explosion if ie headgasket was blown or there was a serious valve/ignition timing issue more commonly known as a backfire.


The areochamber mufflers have no packing so that going to deffinatly cause more noise.My suggestion to you is a borla type setup w/cutout.You also have to remember loud is a relative term to us so I assumed you want to get rid of in car noise at cruise.

MY99TAWS6

iTrader: (3)

Well this morning it didn't seem as loud as last night. It is hot today in the 90s and last night was still up there maybe 75 or so.
Today it seems about right. I think will still quiet it down a bit and then can open cutout when want it louder anyway.
I have found a things to try. Easiest is these CC inserts that fit in exhaust pipes. They have two and three disc versions. Look simple and no welding except for maybe tacking in the insert if you don' want to screw it in. Other option is spiral twister like flo pro that have in my 96z.

People really don't seem to notice the cars exhaust that much and have not attracted any attention from the boys in blue so far. My hooker does get loud under wot and from about 3000 up it start to get louder. I am going to 4l80 swap so not sure what effect going auto will have. Would think a bit quieter since i keep the car sometimes in second instead of third in the city. Not sure if guys go to fourth very much in town.Talking the m6 and of course auto always upshifts pretty much to higher gear. I have 3.54 rear gears so don't rev out that high really. Obviously having gears like 3.08 would lower the noise of the exhaust at cruise too but my rear end has limit of 3.54 and while turbos do ok with the lower gears like 3.08 I still think they are too doggy for me around town which is where most of my driving is.

SincalT/A

iTrader: (16)

Sometimes certain exhaust will have a sweet spot so to speak where it just resonates bad.More often then not it happens right where you cruise around(2200-2800).Other than cats you would need a muffler with a good amount of packing to help cancel it out.A bullet type in the intermediate pipe would help with your current setup.

ta02zx10r

iTrader: (19)

Yeah but the sound doesn't just cancel itself out as soon as the explosion happens. Not to mention that there is VERY LITTLE time in between the compression cycle and the exhaust cycle. There is no way that the exhaust sound is made from the valves and air being forced out of the cylinder. If that is the case then why isn't the intake side sound like a huge vacuum cleaner if it is related to the exhaust side's sound. Not trying to start a war just trying to learn.

SincalT/A

iTrader: (16)

I want you to do a couple thing.
1 go to youtube type in (inside a v8 engine at idle speed)watch the vid.
2 go to any one of your current vehicles pop the hood pull the air filter.Start the vehicle have somone rev it up for you and listen.
Last I would like to debunk your explosion theroy by saying.

"I once farted in a jar to see if I could trap the smell.I opened the jar the next day and sure as **** it smelled but,what was not present was the sound."
Point is sound waves do not wait for a exhaust valve to open.

SincalT/A

iTrader: (16)

One more thing before you say the exhaust valve opens before sound leaves the chamber.
ls1 pistons travel an avg. of 192mph @7000rpm.
The speed of sound is 768mph.

Btw:The combustion process is a burn not a explosion.

Cause explosion=

ta02zx10r

iTrader: (19)

ok do me a favor and pull all the wires on your spark plugs and crank the engine over. If your theory is correct, the sound of the engine should not change since it is in fact the valves/pressure and air that makes the sound and not the burn or explosion of the fuel which has no affect on the sound of an engine. Point being if your theory is the correct one then why does a f-body that makes 310hp sound so much different than a f-body that is putting down 1000hp. It's because of compression/and the amount of fuel and air that is burned in the cylinder. Also sound waves bounce! Have you ever heard of echoes. I realize that echoes aren't noticeable something like a 4" bore but they don't just immediately go away. If the sound just goes away then how the hell does it seem to make it to a muffler who's job is to deflect/absorb the sound and cancel some of it out. Better yet it even makes out the tail pipe by golly. Especially in a tiny cylinder made of metal. Next thing I your going to tell me is it's the air rushing out of a freakin bomb that makes the sound and tears **** up.

SincalT/A

iTrader: (16)

Hey I am not going to go back and forth on this.So I will agree to disagree.



Btw:Look up how a echo happens you might learn something.

ta02zx10r

iTrader: (19)

http://www.acoustics.org/press/131st/lay01.html
I realize that this isn't cut and dried but read this. They claim: A large part of the deterministic component is due to the combustion of fuel in the engine cylinders.

ta02zx10r

iTrader: (19)

That is ford motor company by the way.