ok, what do you guys mean by BOTTLE NECK when it comes to exhaust?

can someone explain that to me please?
thank you

 

Prime example of ITR bottle neck. It's when the gases of a larger tube flow into a smaller tube that has an abrupt change in diameter. This will generate turbulence.



Now a taper is completely different. The gases still go from a larger tube to a smaller tube however this is accomplished by using a smooth taper in the tubing versus an abrupt change. Here's a picture of a taper that goes from 2-5/8" OD to 2-3/8" OD.

 

when a larger pipe flares down to become a smaller pipe, similar to a bottleneck. Ususally done for noise restrictions

 

so, most Aftermarket catback exhaust is like this?

 

the "bottleneck" on the Integra B pipe is to make sure the cat is up to temp, for emmisions control.


The term "bottleneck" refers to the slimmest point, or point of highest restriction...like a bottle neck.... and can be used in many contexts.. not just exhaust