Originally Posted by twowheeladdict
Not offending my tastes, just the science behind a properly tuned exhaust system. Seriously, if you just want louder, drill some holes internally through the baffles. Louder and only your time spent.
However, in the science of a properly tuned exhaust, a right amount of back pressure is a misnomer. While the design parameters for a 4-stroke exhaust system are somewhat constant as in: flow and exhaust velocity, pulse tuning and noise abatement, the standard approach to designs still result in some form of compromise on some of those factors, as well limitations in how it works throughout the powerband of the engine.
One of those undesirable compromises is back pressure, usually a by-product of trying to quiet things down.
There is a good discussion here: https://motordyneengineering.com/exh...nd-scavenging/
A wide range of testing was performed on a range of different diameters and lengths of exhaust pipes in varying locations of the exhaust system. All of these tests demonstrated different ways of changing exhaust pulse scavenging and backpressure. In all cases the results show scavenging is beneficial and back pressure is detrimental to engine performance. ..."
This summer, using a digital manometer, I will be measuring the pressure of a stock exhaust system under various conditions. Then I'll be playing a bit with mods, while monitoring a/f ratio. Will keep the primaries stock but look at the secondary and muffler for changes.
Ultimate goal is a muffler that can free flow when needed (eg 80%+ throttle) but be quiet when not (eg cruising). May get into "on the fly" variable muffler configs. Will also be seeing what, if any, additional results can be found through ECU remapping.