anyone knows about rear exhaust box?

[BuDavid]

I have a 280Z 1977, and I have a workshop manufactured rear exhaust box,

it s noisy and have circular shape, I need to manufacture a rear box which

has similar shape as the original one, which is mounted vertically so it will be

in the same level with the fule tank below.. does anyone know the inside

design of the box so i can give the sketch and manufacture it? by the way, i

have a 3" exhaust pime with half headders, the middle box is eliminated..

thanx..

BuDavid

[TomoHawk]

You really should have the middle box there. It makes the exhaust sound MUCH quieter from 2000 RPM - 3000 RPM. The middle (or front) box is called a "resonator" at most exhaust places, and the rear one is called a "muffler."

HTH

[LanceM]

The object of a muffler is to cool and slow the exhaust, both making it quieter. I've attached a pic I got off the web showing the internals of a typical turbo style muffler. Hope it helps.

[TomoHawk]

Lance,

the details of the airflow are hard to see (where the air goes through the chambers.) Could you provide the person with a sketch of the airflow?

thx

[LanceM]

Sorry, no artist here, finding pics on the web I can do BuDavid, try a google web search for Dynomax, they are a muffler manufacture in the US and they may have better photos than the one I found showing how their mufflers are built. Another search you may want to try would be Turbo muffler.

[BuDavid]

TomoHawk, LanceM..

thanx a lot guys, I really appresiate ur help.. I'll look for for it on the web, since i looked b4 but didnt use the correct key words i guess..

BuDavid

[TomoHawk]

Here is a document I think you will find very useful:

Thrush BrandTurbo Muffler (pdf file) :

You can change the size to your requirements.

[BuDavid]

TomoHawk

thanks for the file u sent man, i printed it out and I'll go to the muffler shop to ask him if he can do a good one like it, but r u sure that it is the same internal design? adn plz can u find me the outer dimonsions of it? the diameters of the oval shape and the length of the box?

I really appreciate it.. thanx a lot man..

peace

[BuDavid]

i found this design on a web page, is it good? and is it enough to change the position of the inlet pipe to center? i git this pic fromwww.n2performance.com

[240ZX]

The object of a muffler is to cool and slow the exhaust, both making it quieter. I've attached a pic I got off the web showing the internals of a typical turbo style muffler. Hope it helps.

Interesting view of how a mufflers works! However, I think the object of a muffler is to attinuate the sound pressure level (SPL) of the exhaust notes coming from the engine. This is done a couple of way, neither of which include cooling or slowing the exhaust. One method is via SPL absorbsion, as in mufflers with some sort of sound attinuating material (packing). The other is cancellation of a specific frequency range, the frequencies the exhaust creates. This is accomplished with specifically positioned reflective baffling that creates or attempts to create an out of phase condition with that specific frequency range. Basically, if you have a frequency and you subject the positive inpulse with a negative impulse of the same frequency, they will cancel each other out.....you won't hear the frquency.

[BuDavid]

thanx bro, but i 4got to attach the pic last time:( well it is attached now.. have anybody any idea about it?

the picture show a cut away muffler which i took from the lectures from the web site i noticed last time..

in the rear views of the car the muffler is seen and tell me guys if it looks wierd or not, coz it's bottom is higher than the fuel tank.. is it ok to leave it like this and mount a resonator? or just replace it with a quiter muffler? and sorry i guess that the pipe is a 2.5"

[sblake01]

The correct configuration for a 77-78 280Z muffler is center inlet/offset outlet. The one on your car, being round, is center inlet/center outlet which makes the tip sit too high up against the body. The muffler you have pictured next to the pictures of your car is offset inlet/offset outlet which would make it sit to low. What you need is something like this: