digger wrote:Belgian1979 wrote:digger wrote:Most of the glass packs I've used are perforated tube so not directional. They do work well when you get some length and volume.
Agreed. But it depends on what you want to have in terms of sound. Smaller volume attenuates at lower speeds but gives off brutal sound at higher engine speeds.
i ran two short hot dog cylindrical resonators in parallel part way down the exhaust on a twin exhaust system and it was terribly droney at low rpm.
So i designed a bigger volume one basically joined them like an oval twin in and out straight through muffler and it was significantly better. due to space restrictions the length had to remain about the same and it was maybe a 2" longer body. i am not sure if having the two pipes being able to someone communicate with each other (each pipe is connected to the same volume stuffed with glass and stainless wool) had any effect.there was an existing rear muffler that remained the same
Joining exhausts of opposite banks has this effect.
If you have lower volume there is less room for expansion of the gasses. So when rpm increases and exhaust gas volume the muffler is already full due to which most gasses just go straight out. My 0.02$