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Originally Posted by Al Weyman
Am I reading this correctly Goran because it appears you are saying NO discs fitted gives more power because that is not the way I read it from the Supertrapp instructions that came with the units. They say the more discs the more noise and more power as you are opening up the restriction.
While we are on this subject can someone ofer some advice on silencing
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If we discuss the exhaust from the starting point at the heads of the engine, we got a primary pipe that has to have a diameter that create the desired gas speed and a lenght that put the return pulses at the desired rpm. We might put this at peak Tq or peak power or at any place we want them, I am just ralking priciples here.
Then we got a collector that also could be constructed in different ways which is a bit more complicated these days. "Merge" collectors is popular and very good but a little tricky to fabricate. They may also be followed by a short timeglass shaped tubing. The "Merge" collector is a well flowing device.
Then we got the opposite collector that is more "pulse" oriented, and can be found in older English books. In fact it could be seen in the film "the Persuaders" with Roger Moore from the 70s "someone waiting".
It is a baffle type collector letting all tubes enter the collector in a flat "wall".
I mention those two types of collector to show the two features that must be taken under concideration when building collectors.
After the collector we got the collector tubing tha should be about the same lenght as a single primary pipes, and a suitable diameter for the number of primarys in question. We can call it System A.
OK, this is about the exhaust system. But the we may use a longer pipe under the car depending on wher to locate the exhaust behinde the car.
We may have a silencer etc, and here we may face a number of problems. We may experience a power gain when changing a silencer for another, but this is due to that the first system was HURTING power.
We NEWER get better than the first basic system mentionend.
Supertrapps on a Pantera is a special situation. The collector pipe is very short and a no disc system is very close to system A.
If the system A is the perfect system what do we do to silence it? The trick is to simulate an open atmosphere at the finisch of the collector pipe, to make the engine think it breath in the "open". So, we need an expansion chamber at the end of the pipe. This chamber should be made as large as possible. The expansion chamber should in turne be "wentilated" to the free atmosphere over some type of silencer.
Without writing a book here, this is the layout of the system.
Goran Malmberg