Intercooler pipe sizing

[flaatr]

If this subject is covered elsewhere please let me know... I haven't found the info I'm looking for but I figure there is a turbo guru out there that can help.

Given that the J pipe (well it's not really a J shape but you get the picture) is a 2" and the inlet of my intercooler is 2.5" I need to step up the size of the pipes some where.

The question is basically one of velocity vs. volume.

Is it better to step to the larger pipe close to the intercooler inlet hence having higher velocity air from the turbo or step up as soon as possible which would reduce the air velocity by increasing the volume? Post intercooler I understand that volume is more important so bigger pipe... but how about pre?

-Raffi

 

[tkelly27]

You'll want to go to the larger pipe sooner. The difference in volume that has to be filled is minimal, the effect on spool will be unnoticeable if there is one.

That pipe in a short route is so short, it is likely that it is more important to make a smooth tapered transition than how long the air spends in either diameter pipe.