Mandrel Bending is a process of curving tube while maintaining a consistent diameter. During the process a steel mandrel is inserted inside the tube, and a wiper die holds the outside of the tube in place. A mandrel bending machine can then bend the tube to the desired radius without distorting the shape of the tube.
We believe a true performance exhaust is best achieved with mandrel bending as it gives the best possible flow of exhaust gas without any restrictions.
The majority of exhaust shops use press bending machines which curve tube to the required shape without anything inserted in the tube, resulting in distortion as the tube folds on itself. This gives a similar result to most standard exhausts from factory. This is perfectly fine if you are not chasing performance.
As well as using mandrel benders to custom make all our exhausts, we also try to use larger radius bends wherever possible to further enhance the flow. Tight bends will slow down the flow of the exhaust gas and should only be used if tight undercar spaces leave no other option.
The full range of SR4x4 3" turbo back performance exhausts are manufactured using our CNC mandrel bending machine.
These pictures show our CNC Mandrel Bending Machine, the mandrel inside the tube and the difference between a mandrel bent exhaust pipe and a press bent exhaust pipe.