1ZZ throttle body = 1.8L CAI?

[Bluevitz-rs]

Area of a 2.25" pipe --> 7.0686"

Area of a 2.625" pipe --> 8.2467"

∏D=Area

So that's roughy 16% more surface area. If you corrected the fuelling by approximately that much you should be alright.

[CrankyOldMan]

Originally Posted by Bluevitz-rs

∏D=Area

∏D = circumference
I get what you meant though. =)

A = pi * r^2

2.625" = 5.41 in^2
2.25" = 3.98 in^2

which is actually a 36% increase in cross-sectional area.

As far as the air velocity slowing down, that's because the displacement of the engine can only "suck in" so much air per stroke? I was thinking of it in terms of the air blowing into the larger filter and tube, but I guess that doesn't matter if the valves aren't open.

So assuming that I get a piggyback and correct the A/F ratio, does the engine actually get more air/fuel per stroke?