Civicman86

OK well its about time to start hacking away and making my pipes for boost. I have heard many different "opinions" on the best way to do this.

My question is, is it better to step up the diameter of the pipes after the intercooler. like say from 2.25->2.5?

I was thinking that smaller on the out side of the intercooler since the air becomes more compact since it cools.

Please dont just respond with yes or no. I would like to have some technical info in here, not a pissing match

miro_gt

do all pipes 2.5" diameter .. . that's what I'm doing ... no issues after that

MooreBoost

You could do 2 inch turbo to FMIC, then 2.25, then 2.5 to the TB.

Im not 100% sure the 2 inch is large enough though, should be for small boost though.

tjbizzo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MooreBoost &raquo;</TD></TR><TR><TD CLASS="quote">You could do 2 inch turbo to FMIC, then 2.25, then 2.5 to the TB.

Im not 100% sure the 2 inch is large enough though, should be for small boost though.</TD></TR></TABLE>
I think perhaps you meant the opposite. You would want the largest pipe where the air is hottest and least dense (turbo out --&gt; IC in) and the smaller pipe where the air is coolest and most dense (IC out --&gt; TB). I have heard a few times that it is a rule of thumb that you don't want the air anywhere in the intake tract to exceed about 175-180 fps. Just what I've heard, and it's free advice so please don't take it too seriously.

YiNYaNg

Smaller pipes take less time to pressurize.
Increases throttle response...

mrbsponge

my drag kit came with 2/25 from turbo to fmic, then 2.5 to the TB im pretty sure they did it for a reason, i still have those same diameter just different piping

XSIintegra

Whats the diameter of a T4 housing outlet? I stay with that size till you hit the IC, then 2 1/2 to the TB.

platinum00

make the piping the same size as your Throttle Body.

MooreBoost

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">
I think perhaps you meant the opposite. </TD></TR></TABLE>

Nope, I have it right.

pontiac power

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MooreBoost &raquo;</TD></TR><TR><TD CLASS="quote">

Nope, I have it right.</TD></TR></TABLE>

^ More Boost = Correct


Modified by pontiac power at 9:24 AM 3/5/2005

tjbizzo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MooreBoost &raquo;</TD></TR><TR><TD CLASS="quote">Nope, I have it right.</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pontiac power &raquo;</TD></TR><TR><TD CLASS="quote">More Boost = Correct</TD></TR></TABLE>
Help me to understand this guys...you want the smallest pipe where you have the largest volume flow, and you want the largest pipe where you have the smallest volume flow? I always thought you wanted to change pipe size to maintain about the same flow velocity everywhere in the system. Could someone please explain why you would want to do the opposite? TIA

BlueShadow

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">Help me to understand this guys...you want the smallest pipe where you have the largest volume flow, and you want the largest pipe where you have the smallest volume flow? I always thought you wanted to change pipe size to maintain about the same flow velocity everywhere in the system. Could someone please explain why you would want to do the opposite? TIA</TD></TR></TABLE>

I would think that going from a 2" compressor outlet right to a 2.5" or 2.75" intercooler pipe would slow the air velocity coming right out of the compressor. If you maintain the same compressor outlet size and IC piping right after the compressor right up to the IC, your air velocity will be higher. And I think that would translate to less lag, better response and maybe less pressure drop too.

EDIT: ideally you will want to keep the flow velocity up. going with a IC piping that is too large might hurt flow velocity. An IC will hurt flow velocity too but since there is no avoiding that, you just make the IC as efficient as possible.

Plus transitions hoses cost so much anyways, so you wanna use as few of them as possible. A 2" to 2.5" transition hose will increase the cost of your setup by $20. hehehe

mrbsponge

i do see where you are coming from, when i went from my darg intercooler to something larger my spool time increased by almost 1000rpms, so piping and intercoolers do a play a part in boost lag.


but i think i heard someone say that the answer to all the piping size problems was to run more boost!!!! ahhah

MooreBoost

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrbsponge &raquo;</TD></TR><TR><TD CLASS="quote">
but i think i heard someone say that the answer to all the piping size problems was to run more boost!!!! ahhah</TD></TR></TABLE>

Thats the answer to any problem.