2.5 - 3" will i benefit

[dr_jekyll]

hi all,

 

i currently have a 3inch downpipe from my gt40088 bi=ut at the join my exhause is 2.5 diamiter pipe.

 

my turbo dose not come onto full boost until 4000 rpm.

 

will i benefit from fitting a full 3 " system from the downpipe. i have baught it but i dont want to fit it if there will be no rear improvement from it.

 

will my tubby spool faster? and i was told the ability to clear faster will allow my egt to cool faster?

 

all comments apriciated.

Edited May 25, 2010 by dr_jekyll (see edit history)

[Kirk]

Your catback shouldnt be smaller than your downpipe as it create's restriction which is BAD! You want a 3" on there to let it breathe properly

[suprab]

interesting question, i have a similiar problem.. single turbo but my decat 2.5" and everything else is 3"

[dr_jekyll]

thanks martin the 3 inch shall be fitted .

[Homer]

Yes, you should really be using a 3inch 2nd pipe with a single turbo, especially if your DP is already 3 inch. My old 2.5inch 2nd pipe was a restriction, not for the spool, but at high rpm's it was casuing a restriction. After changing to a 3 inch it performed a little better at high rpm.

 

In which gear is it "coming in at 4k"? How much boost and is "coming in" considered maximum boost?

[dr_jekyll]

well it hits full boost 8psi at 4k in 3rd gear. by coming in i mean it kind of goes from vacume to full boost straight away at 3.9-4k

 

if that makes sence. i know the map iss all wrong so thats probably the reason for this

Edited May 26, 2010 by dr_jekyll (see edit history)

[Tricky-Ricky]

I had a 2.5 decat pipe in my exhaust with a GT4088 and i could make 1.3bar by 3,800RPM and it made very good power and torque, so i doubt 0.5" will make a big difference, unless you are going for a drag setup or very high power where every little thing will have an impact.

[dr_jekyll]

I had a 2.5 decat pipe in my exhaust with a GT4088 and i could make 1.3bar by 3,800RPM and it made very good power and torque, so i doubt 0.5" will make a big difference, unless you are going for a drag setup or very high power where every little thing will have an impact.

 

no im not . its being mapped by ryan on the weekend so ill put it on before then just to be on the safe side , it wont hurt to have a slighty freer flowing pipe will it ?