What Piping Size To Use?

[rice_me_up]

hi all. sorry if this is an issue thats been covered before.

i have an r32 powered by the rb20det. i have a long list of mods (most of which have been purchased but havent been installed yet but will be very soon ) which are as follows

GT3071r (apparently) with .64 rear and .70 compressor (externaly gated)

r32 gtr intercooler

power fc

oil cooler

3inch exhaust turbo back

suitable injectors and fuel pump

excedy h/d clutch

z32 A/F meter

my aim is approximately 230-240 rwkw.

the question is what would be the best various sizes of intercooler piping?

should i go turbo->2"->intercooler->3"->throttle body

or turbo->3"->intercooler->3"->throttle body

or turbo->2"->intercooler->2"->throttly body

also note that the end tanks on the cooler are 3" and the throttlebody and turbo outlet are both 2"

Does it even really matter?

thanks in advance.

james.

[rice_me_up]

what? so nobody knows?

bah humbug.

[Adriano]

Im pretty sure the throttle body isnt 2", but 2 1/2" piping will be plenty for the power you want to make, and it isn't as hard to fit as 3"

[Bl4cK32]

7" all the way through (u may need reducers on the end)

Edited November 19, 2006 by Bl4cK32

[R31Nismoid]

Piping = same size as the throttle body

thats how mine has always been and most cars i see are the same. You dont need it any larger

T/B isnt 2" though i dont think

[rice_me_up]

cheers guys.

and your probably right about the t/b size. i was taking a stab in the dark.

ha ha @ 7" piping.

cheers. james.

[RB SANDY]

2.5 in is a good med if you want to run no bov and have a dose setup go for the 3 in but otherwise 2.5 in is good.

[HRthirtyone]

i have run 3" and 2.5" and 2".... just like r31nismoid says, keep it the same as the throttle body.

definitely go 2.5. 3 is too laggy, and you may find 2 is too restrictive for that size compressor

[paulr33]

2.5' should be normal for most cars

[HRthirtyone]

yea apparently you dont need 3" until your flowing close to 1000hp.

[rev210]

sometimes a little larger when going around a sharp turn helps the airflow. you sometimes see elbows in factory turbo cars that are larger diameter than the rest of the pipework. They usually have a reducer flexible pipe to attach to the smaller pipes on either side.

The 2 1/4 or 2 1/2 inch is probably about right for the 260-280kw worth of airflow ( 240rwkw ). Like anything make sure you have as short a path as you can, try to avoid sharp bends in the pipework and where there are bends ensure they are well made (I guess most are these days).