ESE's works engine tuner

**JdG** · 13th October 2025, 03:13

I know there has been a lot of talk about hydro formed exhaust, especially about the cons.

But I think this video is worth to watch.

https://youtu.be/nRP-MMZlzJQ?si=MG6j_xDxIMwnnb-k

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**husaberg** · Yesterday, 18:42

**Peljhan** · Yesterday, 20:47

Originally Posted by JdG

I know there has been a lot of talk about hydro formed exhaust, especially about the cons.

But I think this video is worth to watch.

Very good fabricating skills.
I made about 50 different hydroformed exhaust for mopeds, but my procedure was a bit different.
I cut the shape, weld the edge with TIG without rolling the edge, pump the exhaust with strong pressure washer and if the seam poped, weld it back together. Than I welded all the seams around with TIG again so it was smooth. Pressurized the exhaust with air and heated wrinkles with acetilene-oxy torch and a bit of hammering. Than cut and rotate where needed.
My way avoids so much hammering he demonstrated.

I think the 5-7% reduction adjustment in diameter he makes on template is same as welding the seam directly without rolling as welding "eats" a bit of metal. I also figured out how much tighter the radius gets after forming and I think the coefficient was around 0,81. If you want 100° bend, you shoud make it 81° on template.

I started building exhaust from cones later as I made them for racing mostly. Hydroformed were quite ok for stock mopeds. I never did comparison hydroformed and coned on dyno, but that would be my wish someday to compare the performance.