280S Scratch Built Exhaust System Update.
Discussion
Some time ago I posted details of the exhaust system I had fabricated from stainless steel for my S1. I attempted to copy the original TVR design insofar as I was able to ascertain it. Once fitted it resonated and vibrated appallingly!
At long last it is working well and sounding good. The main problem was that the large flat surfaces of the cuboid expansion and silencer boxes resonated. I could actually see them vibrating as I revved the engine.
I have welded stiffening strips along and across all these surfaces; centrally along the length of the sides and the top and bottom of the front section and the bottom and sides of the rear section (which has a rounded top) and transversely around the corners on both sections every six inches. Unfortunately it doesn't look very nice but it has worked.
Another issue was that the perforated tube inside the front section, a sort of squashed oval section (not quite a figure 8) had blown out in the middle when under heat and pressure waves so that it was vibrating against the outer casing. I had to slit open the top of the chamber and remove it completely. I then made sure that the front end of the box where the two pipes come in would be strong enough without the core. With hindsight I would use two perforated tubes through the front section although I believe TVR used an oval over both pipes.
The rear section is divided top from bottom by a sawtooth profile sheet of stainless steel with E-glass above it. So the front section is an expansion (and echo) chamber with the silencing done in the rear section, but very free-flowing. It is loud but not too loud and for the first time since I bought the car in January I like how it sounds! It was off the road from March until August but passed the MOT first time despite the exhaust not being right, which has made subsequent development work much easier! How the original system avoided resonance problems I don't know as I've never seen one. Thicker steel? Internal reinforcement?
At long last it is working well and sounding good. The main problem was that the large flat surfaces of the cuboid expansion and silencer boxes resonated. I could actually see them vibrating as I revved the engine.
I have welded stiffening strips along and across all these surfaces; centrally along the length of the sides and the top and bottom of the front section and the bottom and sides of the rear section (which has a rounded top) and transversely around the corners on both sections every six inches. Unfortunately it doesn't look very nice but it has worked.
Another issue was that the perforated tube inside the front section, a sort of squashed oval section (not quite a figure 8) had blown out in the middle when under heat and pressure waves so that it was vibrating against the outer casing. I had to slit open the top of the chamber and remove it completely. I then made sure that the front end of the box where the two pipes come in would be strong enough without the core. With hindsight I would use two perforated tubes through the front section although I believe TVR used an oval over both pipes.
The rear section is divided top from bottom by a sawtooth profile sheet of stainless steel with E-glass above it. So the front section is an expansion (and echo) chamber with the silencing done in the rear section, but very free-flowing. It is loud but not too loud and for the first time since I bought the car in January I like how it sounds! It was off the road from March until August but passed the MOT first time despite the exhaust not being right, which has made subsequent development work much easier! How the original system avoided resonance problems I don't know as I've never seen one. Thicker steel? Internal reinforcement?
Edited by YeS1tis on Monday 25th August 13:05
Edited by YeS1tis on Monday 25th August 13:06
I apologise for the lack of paragraphs on my posting which I've now edited, adding a pic of the completed system before I welded reinforcement all over it, which I also attach here. I've also had a look at the other thread. Is that really what the original silencer is like inside? I've done the sawtooth profile with a lower amplitude and higher frequency, i.e. more waves but shallower.
Edited by YeS1tis on Monday 25th August 23:13
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