exhasut noise?

[oh to dream]

everyone you ask states that larger exhausts are louder, but whenever i see a gtr or the like with a larger aftermarker exhaust (3-4 inche diametres) they are pretty passive and even at higher rpms you don't hear a roar. can someone please clarify exhasut noise and size for me.

thankyou

[WazR32GTSt]

my opinion is:

energy is created in teh engine from the release of chemical energy in fuel to mechanical energy through the driveline. Of the products of the reaction (exhaust) which still contain energy this is released of which some is released into heat, some into noise and some as chemical energy still.

If you have a turbocharged car (or 2 turbo's), then the wheel spinning in the exhaust uses energy from the exhaust gas in the form of heat and mechanical energy thus leaving less energy in teh exhaust and thus a reduced amount energy to be lost as noise.

summary:

if the car is non-turbo then louder

if the car is turbo then quieter (especially if twin turbo)

Note: this explanation is purely from a physics explanation based on the theory of energy conservation.

[SeriesIIGTST]

i have a 3" straight through from the turbo, two decent mufflers and she's pretty quiet most of the time. most NA 4's are louder than it. However, bring the needle the fun side of 5 grand and you know all about noise. A lot depends on the degree of muffling your exhaust has as it slows down the gas flow which subdues the noise somewhat.

[WazR32GTSt]

yeah but if you compare exactly the same exhaust on turbo and non-turbo car's then you will find that the non-turbo is louder for the reasons above.

obviously more rpm = more energy release and subsequently more noise

[rs73]

My 3" full exhaust system is pretty quiet on idle.

Following the "theory of energy conservation" mentioned above, up to 2000rpm my exhaust noise increases quite a lot like a big grumbling vroooom, due to the fact that perhaps the energy has not been used to spin the exhaust turbine wheel that much. Once past 2000rpm, where the energy would have been used for turbo to spool up and boost, the noise becomes a quiet sounds more like raspy rrrrrrrraaaaahhh.... tone.

Then of course 5000rpm plus it gets pretty loud he he he....

Not to mention the occasional "bang" from the overly too common exhaust pop noise... probably running too rich.

On NA cars, esp Civics, Excels, Integras, if they put some aftermarket exhaust, it never sounds good. All the ones I've heard on the street so far sounds like a terrible squeezed fart. Vvvbbreeeeettttttt........

[4 Doorz]

Though Turbos are why quieter coz the turbine wheel 'smashes' the sound from the manifold and the sound is muffled by having to get thru turbine wheel. Simply just like shutting the door to a room of loud music, the sound waves bounce off or are absorbed.

[WazR32GTSt]

4 doorz what you said is true. closing the door to the room absorbs the energy in the sound...

its all about physics!

[aybee]

depends on the resonator and muffler.

ive had both 3.25 and 3.5 on my car and the 3.5 was a fair bit quieter.