Ok guys, so i went to a local muffler shop to get my exhaust put on, i ordered 2.25" piping and a muffler off ebay. The setup looks great and it sounds pretty deep and loud. A few weeks later, this guy asks me if its mandrel bent, and i had no clue what that means. I found out its when they stretch the piping, then bend it yielding better airflow, where as my exhaust was just bent, resulting in less air flow. Now my question is, is there a big difference between mandrel bent and regular bent piping? I'm actually going to get a quieter exhaust, maybe a twin loop or a stock one, how does mandrel bent piping play into that? More power? Louder? Thanks guys.

 

Okay well dispite the fact that this might be the wrong forum for this post I'll go ahead and answer your question. Mandrel Bent piping yields less restrictive flow because the bends in the pipe are smooth and have less impediments where as "Regular Bent" which I presume you're reffering to Crush Bending has quite obvious signs of an inferior quality the piping would be slightly dent from the pressure that is being applied to it where as the use of the mandrel helps to smooth it out and reduce some of the direct stress placed on the piping . Purpose of a twin loop is too eliminate some sound waves, it restricts flow in some sense because it generates some backpressure; I forgot what you posted at this point exactly but odds are if you looked at your piping and said "This Expletive looks Great!!!!!!!" that it's not crush bent cause you woul have said "Oh Expletive, this is bad, hiteous pipe why did I pay for it...... "

Anyways hell with it....oh and if I were you I'd quiet my Expletive (for muffler) down because of all the cops and increasing fees over minimal crap when Harley's and those expletive Chevy trucks drive by with those loud flowmasters

 

he forgot to mention the biggest thing is not that theres a "dent" but that the diameter is drasticall decreased at the bends with crush bent tubing.

also the twinloop is not made to "Create bp" everything in your exhaust makes backpressure even the tubing, due to friction. but the soundwaves thing is correct.

 

Ram forming --- referred to as crush or regular bending have a typical reduction tube diameter through in radius ranging from 20% on a large radius down to over 50% reduction of radius on a tighter radius bend.

Rotary bending - mandrel or no mandrel depending on application will yield anywhere from less then 1%-3% with mandrel to 5-10% in large radius heavy wall without mandrel applications.