ok, ok. different catted downpipes each sound uniquely different from eachother. that makes sense, because each have their own restriction.

catless downpipes, however, have no restriction, which leads me to believe that every catless downpipe is litterally just a pipe and different open downpipes are all the same (with the exception of build quality, weld quality, material, etc.)

my question is, do catless downpipes made by different companies actually sound different or for the most part, do they all just sound the same because the way i see it, ultimately, they are straight through pipes with nothing inside them thus causing open downpipes to all sound the same.

let me hear your ideas, agree with me or correct me please.

 

that since every pipe on a pipe organ are all just open pipes at one end, that they'll all sound the same. They don't.

To get more technical about it, yes the length of a pipe sets it's fundimental pitch, but the shape will affect something called "mode coupling" which is how the fundimental couples to overtones.

Also, the thickness of the material and it's type will effect how the sound is generated through the pipe, not out the back.

How they are flanged and connected will also affect how they couple to the rest of the system, and how the end acts (totally fixed vs totally free, this changes the fundimental frequency).

Matt

 

very interesting Dr Obnxs. considering these differences you mentioned such as thickness of the piping and so on, how different could it actually make the sound of the exhaust be? will it significantly change the sound and tone? or are u speaking of a louder or quieter exhaust?

thank you for your input either way!
anybody else have any comments about this?

 

but I don't know how much or what a big difference is to you or others. It's very subjective.

In cars, the primary frequency is determined by engine RPM. The "shape" or "depth" of the sound, as well as it's volume, will be effected by tons and tons of things in the whole exahust system. Probably the biggest "lever" here will be the mufflers.

Want to know for sure? Get a bunch of downpipes and test em.

Matt

 

dj- thinking about it more, the thickness of the downpipe and exhaust material will definitely change the tone, the "gauge" or thickness of the metal used, as well as aluminzied steel or stainless steel, will all make a difference. The way it makes the difference is the way that the vibrations/soundwaves travel through the pipes. Think about smacking different types of wood, solid, hollow, thin and thick. They all sound different, even though they are all wood.

To Dr O-- dj asked me through email about this because he installed the same muffler as I with same tips and at the same size piping (2.5"), from the DP back with no res no 2nd cat and just the muffler. But he says his exhaust sounds way different than mine in my videos (youtube: akakong88) and his is raspier. I told him with the open dp it'd def be raspier, do you agree?

 

yes I do, the less restriction the more raw a sound....

But I'm really the wrong guy to get into details like this with. The reason I say that is I don't really care about the shape or tone of my exhaust. I can does it make power and does it drone. Also, is it too loud. That's about it.

Matt

 

just to clarify...
BostonR56S: my car doesn't sound raspier, its just the opposite. it sounds very mellow and muffled, kind of like a hollow can. the video you have on youtube with the videocamera right above your tips under heavy load, you can really hear the engine, which i love.thats exactly what im looking for!

 

Sorry about the off-topic question, but how much of our exhaust system can we gut before running into sensors !??!

 

There are only sensors in the downpipe

 

Question. Will the cel from the dp cause the car to go into limp mode? Id like to run a dp on my factory jcw exhaust. I've heard on here that it sounds good and you get that lil extra bump in hp.

 

I got around 10hp just going catless. Yes, you will have a CEL...no it wont make it go into limp mode. Ran mine with the P0420 code for over 10K with no issues. Catless on the Factory JCW exhaust sounds like sex...its pretty darn loud at WOT though

 

Yes !!! Thank you sir... That's what I needed to hear.