so in theroy silencers dont do much in restricting power or im i talking poo?
I always thought the boxes distrube air flow and slow the gas speed down so the less boxes a system has the better gas speed n flow, for example on the brothers GSi we changed his standard exhaust system(3boxes) for a standard 1.3SR system(2boxes) and guess what the car pulls much better though the rev range now!
So why did vaux slap 3boxes on the 1.6 non cat engines but only 2 on the carb models?
yeah as above. whereas aftermarket silencers are usually of the absorbtion variety. using a perforated tube through the silencer case and packed around the outside with fire proof matting material.
what do you want? .. quiet loud.. good mid range or all top end? ..if its a 1.4 a three box absorbtion arrangement is good. This free flow thing is deceptive ...you want the gasses in side to resonate ..cos the negative pressure waves travelling back to the engine can scavenge and help the incoming charge ..(valve overlap) .. you want gas speeds to be high ..so wrap the exhaust manifold ..and go for the smaller diameter pipe. The nearer the first silencer is to the engine the better top end you will have
im sure a exhaust system with no box works very well only on engines that rev to 20,000rpm like the F1 cars but street cars need to have the exhaust note low or you get fined or something (i almost did once with a peco) and a street car needs power n torque below 7,500
See.... I read a bit about exhausts and back-pressure and stuff. And I got the distinct impression that (even for a road car) no 'boxes is best.
Seeing as how all the back-pressure the engine needs is created in the headers, the rest of the system just needs to get the gases out as quick as possible.
I'm seriously hoping I understood (and remembered) this right....
On the Monza (as an example, it's all I have to 'run with'), I only have a straight through backbox (the internal pipe is straight and perforated) and I'd like it less restrictive and louder.
I've been told the backbox provides very little silencing, but the 2 pipes from the downpipes do go into a Y piece about 2ft before it.
So would no 'boxes lose me power by the bucketload?? and would it really be that much louder??
In your case I think I would be tempted to run 2" or 2.25" and 2 boxes. If you had to have 'boxes.
Yes agreed .. If you look around on the internet, stuff on exhausts is hard to find .. this is the best I found http://home.jps.net/~snowbum/InExTuning.htm ...ok ..its about motorcycles ..but its the best out there
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