This is just a fun little fact I was wondering about. Say you've got three cars...

Same cars, same cubes, same exhaust, same everything. TR224 in all three, one car is stock heads, one is ported heads and stock compression, and one is ported heads with raised compression...

What is the effect of the head work and compression on the loudness of the exhaust? Does just porting the heads add more umph to the note (ported heads and stock compression louder than cam only setup) or is it the extra compression that gives it more grunt, or would they all sound the same?

Just a fun little fact I've been wondering about. Thanks for any help.

 

well when i put my new heads on i bump the cr to 11.1 i did notice the sounded a little more crisp. but not louder really.i think the loud factor actaully went down alittle instead of up, but that might be due to other factors

 

Mine sounded "a bit" deeper after the heads. Or so I think. I did not think it would change at all but it did seem to affect the exhaust note in a mild way.

 

The cam and the exhaust are the major culprits. The heads... *I've* never heard any difference as long as they are sensibly ported. The compression ratio can change the tone of the exhaust a little... Ive heard that. But you have to have a good memory and the exact same exhaust path. The exhaust almost seems to sound more .... like little individual explosions. It has to be a pretty open exhaust to hear any differece at all though, and it has to be a serious change in CR... like a point or more.

 

loud = volume of fuel/exhaust flow....

so porting heads will flow more and thus get "louder" but without a back to back test with sound equipment I doubt you could really notice a lot.....


if I had to guess, I would say the tone change comes from a better burn causing hotter exhaust temps and thus higher pressures at the exhaust valve open point (gives it that "crack" kind of sound).......


I went from ~10:1 up to 11:1 (went from a 0.045" to a 0.018" gasket) on my 388 and didn't notice any different sound......open headers were always LOUD and "cracked" on the EVO.....I could add 100HP and it would still make my ears bleed just as much .......with exhaust it sounds like it always did....



as everyone said......the cam (overlap), the exhaust (the headers, the Y or X pipe, the muffler/mufflers, and any other pipe), and the CIs (more CIs give more of a "boom" rather than a "crack".........think of a Big Block sound vs. a Small Block.......again....it's the volume of flow) are what really set the "sound" more than anything......