2.5 and 3 inch ic piping question

[projeks13]

so i ended up with just enough piping to make one side with each size(2.5" & 3"). which side should get the 3" hot of cold? i have a medium sized rectangular shaped intercooler not too crazy big.

[nizmo zilvia]

2.5 hot and 3" cold imo.

Since we are on the same subject, which size do you guys recommand on a rb20 with rb25 turbo? Im thinking 2.75 or 3" on both cold and hot. Thanks.

[IronMonkey]

If you have to do it, 3" on cold, and 2.5"

For a rb25 turbo, Id just keep it down to 2.5" all around. I dont see the point of going any bigger if you dont intend on bigger power in the future as it will delay your spool up.

[projeks13]

thanks guys your right about keeping it around 2.5~2.75ish but thats just the way a poor dude ended up

[rbsileighty]

Just some advise...

Try and stay with bends larger than 90 deg if possible if you are making a custom piping setup

As for piping size... I still question the need for 3" piping (can't believe on a car with less than say 400hp 2.5" will choke airflow... unless maybe the amount of bends merrits the larger diameter... but I'm not sure on that... just a guess). If you do use it, please gradually step up to that size, or carry 3" from the IC exit all the way to the TB so you don't get a significant, instant pressure drop in the pipe.