Exhaust Pipe Size Vs Area

[sexual harrassment panda]

thanks mix

[RAP1D]

that's great info, but muffler design plays a huge part in making a system flow and support big power.

Twin 2.5s, single 4inch whatever, if the mufflers wont flow the same, it wont support as much power as it should.

A simple 3.5inch single system can flow massive power with good flowing mufflers, or struggle to make 300kw with poor mufflers.

[FOONIN]

I have been told 3inch is worse than the two 2.25. How is this so? the 3inch will have less frictional area or whatever but more area ......

So what is really better 2 x 2.25" pipes or one 3"?????

Obviously one 3.5" would beat both options???

Edited 01/06/10 04:56 AM by osonvs

[sexual harrassment panda]

single 3" has about .9 square inch less cross section then the factory twin 2.25". The factory twin setup is fed by a section of 3", most custom exhausts get smaller as the get frther from the motor not the other way round. A 3" system with a good cat and mufflers will far outflow the stock exhaust . . . but like you said 3.5" will be better.

[Panda Eyes]

so heres a question-

will my 3.5" dump with separate wastegate pipe, stock 'modified' cat then twin 2.5" redback mild steel system

benefit from replacing the stock 'modified' cat with a big- say 5" 100cpi- cat?

[RAP1D]

Generally speaking, a 5inch 100cell cat will flow more than a hollow stock cat due to the twin 2.25 outlets on the cat, so if you were to replace this section with a 5inch body cat, and re-do the merge section from cat to twin 2.5, it should make more power.

[FOONIN]

I have a guy at my work right who keeps trying to convince me a 3" is better than 3.5"....the math however favors the 3.5" however he keeps woddlin on about back pressure or something??

[ratter]

you do not want back pressure.

[mic]

single 4 inch is only just outflowed by twin 3 inches, and does not split up airflow. as rapid said a single 3.5 will flow ridiculous amounts of exhaust if its quality.

Edited 26/06/10 09:22 AM by mic

[orangeute338]

doesnt the heat make a diffrence? a hotter pipe will flow better, so twin smaller pipes of the same area of a big single should flow a bit better??