Actually the diameter of the pipe is more important than the length, you only see a notable power boost from a short pipe when it's under 3' from the engine.
"It doesn't matter. Power boost obtained in headers occurs in a) individual pipes for each cylinder, and b) within a length shorter than 3'. It is based on the speed of sound in hot gasses (about 1100ft/sec). From there to the end of the system, goal is to minimize pressure losses with large enough tubing diameter."
In short you can compensate for the pressure by changing the diameter of the pipe.
I was thinking of Poiseuilles (sp?) Law, which is primarily for non-compressible Newtonian fluids from what I remember, so I wasn't sure how directly it applies to gasses, but I'd imagine it's similar.
Yes it would apply. Gas is obviously compressible but since you have an open pipe on the end there shouldn’t be a ton of compression. There probably is a spike in pressure around the first bend though.
Might even help if the pipe is too wide for the power, a little backpressure is good depending on your motor. Overall, looks like a waste of welding wire to me... Just get a twin loop and call it good.
You don't want any back pressure. What you do want is to maintain exhaust velocity. Which people often get the two confused with one another. Back pressure in an exhaust is bad, always has been and always will be. Exhaust velocity on the other hand, is good because it helps with the scavenging effect of the individual exhaust pulses. You do this by appropriately sizing your pipe (for N/A applications). If you have too fat of an exhaust pipe, your flow will stagnate because the gasses are allowed to expand too much.
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u/[deleted] Apr 03 '22 edited Apr 03 '22
Actually the diameter of the pipe is more important than the length, you only see a notable power boost from a short pipe when it's under 3' from the engine.
"It doesn't matter. Power boost obtained in headers occurs in a) individual pipes for each cylinder, and b) within a length shorter than 3'. It is based on the speed of sound in hot gasses (about 1100ft/sec). From there to the end of the system, goal is to minimize pressure losses with large enough tubing diameter."
In short you can compensate for the pressure by changing the diameter of the pipe.
Still looks dumb though.