Pipe diameter should be based on hp level combination is at. Some may believe that you can put 500hp exhaust on 300 hp vehicle now you will 500 hp right?! Sorry it doesnt work that way.... lol.
OK.. kidding..... somewhat anyways... hopefully people dont believe that.
Some interesting facts as I understand it.
The exhaust needs to be properly sized to help maintain
velocity and heat in the pipes. The cooler the exhaust gets the more dense which in turn "slows" down flow making it more difficult to expel. Hotter exhaust is less dense and easier to move. Larger pipes not only reduce velocity but have much more cooling surface. Velocity is your friend... back pressure is not. Too small and it restricts exhaust flow at high rpms limiting hp potential. We are shooting for high velocity and heat with lowest back pressure. Obviously its a balancing act and compromise.
I have always known velocity is important when it comes to exhaust but did more research several months back to understand why I get more a bit more condensation than most from my exhaust on cool days. After researching some more and understanding that my exhaust is cooling down (at idle & low speeds) in turn condensating before it exits the pipes it all made sense. H20 by the way is one of the byproducts of combution. Never really considered exhaust
heat from the headers back as a factor in performance before but it is.....
The concensus seems to be 2.25" - 2.5" dual exhaust or 3" single for around 300 hp vehicles. Plenty info online about properly sizing exhaust.
Check out my video shot on a 40 degree day. Exhaust goes from heavy condensation at idle to rich (11.8 ish air/fuel ratio) when opened up. No coolant loss since built...I checked. lol. Its the large 3" dual exhaust pipes allowing it to cool more than average at low loads.
Supercharged Expedition 1/4 mile pass. - YouTube
Sorry about the shameless video plug......I cant help myself sometimes.
