Exhaust Question

[Mat Francis]

Excellent as always MD.

[MD]

just to round off..modern cars put cats where the resonator used to live. this does both jobs. not strictly correct but I'll slip it through and see who trips me up..

[MD]

 

yes that front muffler is a resonator and it has nothing to do with the tuned length of the exhaust or how that affect the torque curve

M.D. is right the length of the pipe does have an affect on torque but on an 85kw alfa your not going to notice it

Glen, you got bob going each way here. Wanna clarify your position ?

BTW1 Everything in this world has a resonance.
       2 A tuned exhaust system is a SYSTEM and the so called headers are but the first stage of this    system.

The only time the resonator has no impact on the system (however small) is when some bird brain installs it outside of its tuned location. Try playing middle "C" in "F" sharp. Somehow it sounds wrong that's because middle"C" has a specific length with respect to the piano wire intended for this note. The correct resonance produces the correct note. The correct resonance between the induction side and the exhaust side produces middle C for want of a better decription. Altering either the induction or the exhaust lengths can produce either less power than possible (de-tuning)or move this power to a different rpm range (peak tuning) but less usable for general road use.

This is a huge topic and so I will end here.

[prova]

Thanks for everyones input on the exhaust query. I kept the front resonator, fitted a straight through muffler in the centre and a hotdog in the rear - great job and only cost me $250 with a two year warranty. Sounds good - no nasty vibrations - really happy.

[Sheldon McIntosh]

So is the resonance the same as harmonics on a (guitar etc) string?

[MD]

Only if you use the G string..
Hey Sheldon, your avatar has fallen off. Too many burn outs in the 90 ? 

[prova]

Who's Bob?

[armc89]

its not a cat cut it ou its just in the way get two 15' hotdogs mounted in there they need to be spaced off centre and uneven to prevent a yucky resonance i think thats how its spelt. those muflers cost about $80 each so not to expesive for you. good luck with the pong system!

[Sheldon McIntosh]

frequencies are sound waves, short waves have a high pitch long waves low pitch
the sounds out of a trumpet are caused by the  breath to push air through and by the player buzzing their lips as they blow, the trumpet also amplifies the sound
harmonics are when two frequencies or more align with each other as in two singers two guitar strings or two alfas together at the same revs, the combined sounds oscillate around each other giving that distinctive sound that you can hear and in the case of the cars you can also feel

Well I'm no musician, but I would have thought that "when two frequencies or more align" would more accurately be described as 'harmonies'.  As far as I'm aware, harmonics are quite different.  But I'm no musician.

I was talking about when you place your finger on (but don't press on it, just lightly on it) a guitar string exactly halfway between it's mounting points, or the 12 fret I believe it is (its been a while) and pluck the string you get a wonderful 'resonant' sound.  From memory you get similar sounds, but at a different frequency, at the 5th and 7th fret.  (Some of that may be inaccurate, It's been a while since I picked up a guitar, and I only did it to pick up chicks when I was a teenager.  And yes.)

What I'm referring to may be better explained in the pic I've attached.    Seemed similar to what people were referring to as resonance, that's all.  Not that I know fuck all, I'm no musician.