Exhaust Pipe Sizing And Mufflers

[rob83ke70]

Hey

I'm looking at quietening the exhaust on the ke55, it currently has a set of extractors, a louvred resonator, 2" piping, a 2.25" rear muffler (straight through offset entry/exit) and a 3" tip.

 

I was thinking about wrapping the extractors, fitting a heat shield for the su carburettors, and putting a 2" pipe size with a 2" ID perforated tube resonator, as long as possible, then smoothly stepping down to 1.75" pipe just before the diff, and a 1.75" straight through muffler with either a 2" or 1.75" tip (straight cut). The basic idea is that as the gas gets further away from the engine it loses head and therefore loses velocity, and decreasing the pipe size at the rear will counter act this (wrx's step the rear section down and actually make more power). The additional flow/heat in the pipe will hopefully make the rear muffler last a bit longer, and hopefully this will be quiet enough to hear the radio on long commutes at 4000rpm.

 

Any thoughts on this? I want a free flowing pipe and as quiet as I can get it. The engine has a 276 degree cam, twin 1.5" su's, and is a bit of a high rpm screamer, not a problem on a race track but is creating hearing problems during the daily driving.

 

Robert.

[SLO-030]

Sounds like a good idea Rob.

 

The same is used in aftermarket exhausts for the old (XY etc) falcons. 2.25in or 2.5in from extractors back and 2in over the diff to the tip.