I've been wondering what causes my exhaust to burble when I let off the gas. You all probably know what I am talking about. I am thinking that it is turbulence inside the exhaust piping. Here's what I think:

The exhaust comes out in pulses, at different throttle positions the pulses change (size, intensity, speed, distance between them, I'm not really sure?). So, as you let off the gas you change the pulses coming out.

Ok, so I think that when you cut off on the gas the pulses move slower or something, and that it creates a larger vacuum behind the pulses already moving out. This will slow them and create turbulence, which could cause them to come out at uneven intervals.

Perhaps this is why I have a burble in my exhaust? (Probably didn't explain it too well)

 

the air fuel mixture turns rich when you let off, thats all

 

Hm.

 

i didnt read the whole post, ya thats some of it too, the pulses are why V8 sound really good, and V12 sounds high strung. My car does it once when i let off around 2k, my friend has a built D16z6 that oes it like crazy because it runs rich normally