I understand backpressure to an extent, but I wanted to be clarified about it.

I see backpressure as a means to create a vacuum at the valve exit, so it allows the exhaust stroke to use less power. If the header is too large in diameter, than the exhaust will need to expand at the exit of the cylinder, causing it to slow down in velocity. So when another exhaust stroke comes, the exhaust isn't moving quick enough through the header, so the stroke will take more power to exhale the exhaust. Am I correct on this?

 

No idea, but here was my take on exhuast piping size. Think of a river, where it's big and wide, the water run slowly, where it tightens up, the river flows faster. Too big a pipe, exhaust slows down, too small a pipe, exhaust gets chocked and you don't get as much exhuast out as you could. Right sized pipe, exhaust flows quickly and efficently (at least for certain rpm's as more exhaust cycles means more exhaust gas). No idea if it's true or not, but just some dumb thing I thought up one day.

 

I kinda understand where your coming from BUT we it comes to a car! In my dumb thinging If you have a bigger pipe I would like the air would flow better But then that leaves less back pressure. I DON'T KNOW! :slap:

 

I would just stick to 2.25 piping for N/A honda's with minor work, 2.5 for worked N/A and 3 for FI.

 

http://www.theoldone.com and search and maybe post in one of the forums if you don't find what you want out of searching.