The local muffler shop will not do [mandrel bends] unless you have the full exhaust system put in by them.

That's because the mandrel costs beaucoup bucks and they gotta make it pay for itself. A mandrel is similar to that pipe-bender gizmo that electricians use on commercial electrical conduit...only bigger, and it's a bench affair. And there's an art to bending a system up so it all fits the first time around without wasting material. You're probably stuck shelling out the shekels for it.

 

mandrel bends are just smooth bends do are the total opposite of a crush bend.. if you go to www.nissanperformancemag.com and see when they do the exhaust and look at pictures you0 will notice that there are no "wrickles" in the piping allowing the exhaust gas to flow better.. thence being more expensive.. you pay for the pay pretty much and the durability is much better..

 

The mandrel bends get there name from the mandrel they insert into the pipe during the bending process. the mandrel keeps the pipe from collapsing during bending and maintains a consistent smooth diameter.
-dave

 

if you ever watch monster garage, jess uses a mandrel bender to do a lot of the work for exhaust and headers..

 

hello...most shops just buy quantity of certain bends...usually 45's, 90's and 180's and then resell em for a decent profit...even the bigger name aftermarket companies just buy raw bends from other places...these other places are few and far between...this one is a good one though...the most sizes and radiuses that ive found...and they sell v-bands, header flanges, collectors, 02 bungs etc...they'll even help you produce a new part to resell...if you send them yer prototype part(header, downpipe, even sway bars etc) they can reproduce it as many times over as you need...cnc or not...they even have 3 inch aluminum

anyway here it is

Columbia River Mandrel Bending - Columbia River Mandrel Bending

 

how hard is it to heat and bend to try to get that mendrel design

 

theres no heating involved....setting up and tuning the bender in is the hard part....takes alot of hands on experience to perfect it so that you dont have tons of waste

 

It's almost impossible to get a smooth bend without the proper mandrel equipment. There must be a mandrel (sorta like an anvil) inside the pipe to maintain the diameter. Mandrel bending is closer to extruding than it is to bending.

Sand bending is an intermediate quality between the mandrel and crush bending, wherein you weld a plate over one end, fill the straight tube with sand then tamp it in. Then weld another plate on the other end, then bend with the sand in the middle. I believe mild heating helps here, but not enough to fuse the sand.

Electricians don't use a mandrel bender, that's just a portable pipe bending lever.

 

Why not just buy mandrel bend pieces? Napa sells them i got 3 inch 45* and 90* for 40 bucks each.

 

the link i posted has them for cheaper

 

I believe Summit Racing - High Performance Car and Truck Parts | 800-230-3030 has them also. many places on the web sell 90's, 180's and 45's in 2"-3"+ diameters. you still have to stretch the ends and fit them into the straight peices then weld them up.

Chris 92 classic

 

the place i posted will also do the expanding if you request it