building a exaust system ???

[evanlotus]

i am going to build a exaust system for my elan. Does anybody have some ideas what works. Super trap???

[ceejay]

Evanlotus
FYI: Have a good read and poke around here for DIY exhaust fabrication. (See Link below) Check out the daggy old 1980s DIY built pipes I used to run, compared to the new pipes I built... must be close on ten years ago now... still going strong. If you have good fabrication skills, a well equipped workshop, and you can Oxy Acet or TIG weld, then you'll be able to build a nice set of pipes for a very low cost... they do take a lot of hours to build, but very satisfying work.
https://elantrikbits.com/lotus-elan-blog/exhaust-headers-twin-cam-lotus/
Have fun
Ceejay

[h20hamelan]

like this
I just ordered some I & U pipe, also a Y
keep y'all updated

[The Veg]

I didn't build a whole system, but when I installed a new exhaust system a few weeks ago and had to add an extension to one piece I found that my cheep little flux-core welder was more than adequate for joining pipe. Turn the settings really low and give it a good cleaning with the grinder afterward.

[Andy8421]

i am going to build a exaust system for my elan. Does anybody have some ideas what works. Super trap???

Supertrapp seems to appeal to the type of buyer who wants to 'tune the sound of their exhaust'. From a performance perspective, it looks to be a dud. In my limited understanding of exhaust flow dynamics, you want a free-flowing system with minimal back pressure to allow maximum extraction of the combustion products from the cylinder. Supertrapp seems to work by stuffing up the end of the pipe, which can't be good.

I can't find any real reviews (that haven't been 'sponsored') but I do have direct experience of fitting a borrowed Supertrapp silencer on to the end of my TTR race system in an attempt to get through the 98dBa noise check at Goodwood. While it passed the noise test, the engine ran so badly, I had to give up.

Perhaps I should have 'tuned' the system by adjusting the number of discs (Supertrapp's big selling point), I did mess about with this but I couldn't get the engine to run well. From my perspective, the overall concept is flawed - you make the exhaust quiet with cleverly designed resonators and wadding around perforated pipe, not by stuffing the end of the exhaust pipe up.

[baileyman]

I wonder about things like Supertrap. They appear to be a variation on a muzzle silencer or a highly directional microphone. For the microphone the slots in the tube are intended to invert frequencies against each other for cancellation. I haven't found anything indicating anyone has really pursued that idea.

My S2000 has a little quarter wave tube branching off, another idea I don't see anyone pursuing in racing. It would be interesting to know what the frequency response is of the mic used for measuring the 98dB. If it has a peak, construct a quarter wave tailpipe branch for that frequency and see how it goes. Or if the exhaust has an obvious peak near 6000 rpm try that.

John

[Andy8421]

I wonder about things like Supertrap. They appear to be a variation on a muzzle silencer or a highly directional microphone. For the microphone the slots in the tube are intended to invert frequencies against each other for cancellation. I haven't found anything indicating anyone has really pursued that idea.

My S2000 has a little quarter wave tube branching off, another idea I don't see anyone pursuing in racing. It would be interesting to know what the frequency response is of the mic used for measuring the 98dB. If it has a peak, construct a quarter wave tailpipe branch for that frequency and see how it goes. Or if the exhaust has an obvious peak near 6000 rpm try that.

John

John,

The SPL meters use an 'A' weighting - details here:

https://en.wikipedia.org/wiki/A-weighting